Keywords
Computer Science and Digital Science
 A6.1.1. Continuous Modeling (PDE, ODE)
 A6.2.1. Numerical analysis of PDE and ODE
 A6.2.7. High performance computing
 A6.5. Mathematical modeling for physical sciences
 A6.5.2. Fluid mechanics
Other Research Topics and Application Domains
 B4. Energy
 B4.2. Nuclear Energy Production
 B5.2.1. Road vehicles
 B5.2.3. Aviation
 B5.2.4. Aerospace
1 Team members, visitors, external collaborators
Research Scientists
 Rémi Manceau [Team leader, CNRS, Senior Researcher, HDR]
 Pascal Bruel [CNRS, Researcher, HDR]
 Vincent Perrier [Inria, Researcher, HDR]
Faculty Member
 Jonathan Jung [Univ de Pau et des pays de l'Adour, Associate Professor]
PostDoctoral Fellows
 Syed Jameel [Univ de Pau et des pays de l'Adour]
 Sangeeth Simon [Inria]
PhD Students
 Puneeth Bikkanahally Muni Reddy [Univ de Pau et des pays de l'Adour]
 Anthony Bosco [Univ de Pau et des pays de l'Adour]
 Alexis Ferre [CEA]
 Ibtissem Lannabi [Univ de Pau et des pays de l'Adour, from Oct 2021]
 Mahitosh Mehta [Univ de Pau et des pays de l'Adour]
 Romaric Simo Tamou [IFPEN, from Oct 2021]
 Gustave Sporschill [Dassault Aviation, until Apr 2021]
Interns and Apprentices
 Lou Guerin [Université de Paris, from Jun 2021 until Aug 2021]
 Nicolas Victorion [Univ de Pau et des pays de l'Adour, from Apr 2021 until Aug 2021]
Administrative Assistant
 Sylvie Embolla [Inria]
2 Overall objectives
The projectteam CAGIRE is an interdisciplinary project, which brings together researchers with different backgrounds (applied mathematics and fluid mechanics), who elaborated a common vision of what should be the numerical simulation tools in fluid dynamics of tomorrow. The targeted fields of application are mainly those corresponding to the aeronautical/terrestrial transportation and energy production sectors, with particular attention paid to the issue of energy transition and the reduction of environmental impacts. In the near future, this panel will also be extended to medical applications, where numerical simulation plays an increasingly important role. Through our numerous industrial collaborations, we have been able to refine our vision of the future of numerical simulation, which is subject to ambitious industrial objectives, constant evolution of computing resources and increasingly present environmental constraints.
Even though it is far from being the only complex phenomenon to be taken into account and the only subject of our research, turbulence plays a central role in this project insofar as it is a dimensioning constraint for CFD in most industrial configurations. It is indeed the comparison of the requirements in terms of scale of description, numerical accuracy and computational cost that guides the choice of physical models and numerical methods. However, these choices must also take into account the fact that the applications may involve many other important phenomena: for example, shocks; but also couplings of lowMachnumber aerodynamics with acoustic waves; multiphase flows; variable density; conjugate heat transfer; etc.
Because such flows are exhibiting a multiplicity of length and time scales resulting from complex interactions, their simulation is extremely challenging. Even though various simulation approaches (DNS1, LES2, RANS3, Hybrid RANSLES) are available and have significantly improved over time, none of them does satisfy all the needs encountered in industrial and environmental configurations. We consider that all these methods will be useful in the future in different situations, or regions of the flow if combined in the same simulation, in order to benefit from their respective advantages wherever relevant, while mutually compensating for their limitations. It will thus lead to a description of turbulence at widely varying scales in the computational domain. For example, the RANS method may cover regions where turbulence is sufficiently close to equilibrium, leaving to LES the regions where the RANS description is insufficient. The models and numerical methods must also be flexible enough to accurately represent all the abovementioned phenomena in complex geometries, with efficient and robust resolution algorithms to preserve an optimal computational cost. It is this flexibility and adaptability of models and numerical methods that we call “computational agility", which is in the title of the CAGIRE team: Computational AGility for internal flow sImulations and compaRisons with Experiments.
Therefore, the longterm objective of this project is to develop, validate, promote and transfer original and effective approaches for modeling and simulating generic flows representative of configurations encountered in the field of transportation, energy production and medicine. In order to progress in this direction, many building blocks have to be assembled, which motivates a variety of research topics described in the following sections and divided into four main research axes. The topics addressed, ranging from advanced physical modelling to highorder numerical discretization, require the multidisciplinary skills that constitute the CAGIRE projectteam.
 Turbulence modelling
 Highorder numerical methods and efficient algorithms
 Development of specific numerical schemes
 Analysis and simulation of turbulent flows and heat transfer
3 Research program
3.1 Turbulence modelling
In the “agile" simulation methods introduced above, a flexible representation of turbulence is essential: in the same simulation, depending on the regions of the flow, it is necessary to be able to switch from a finegrained to a coarsegrained representation of turbulence. Numerous methods, called hybrid RANS/LES, go in this direction, by associating LES and RANS. In order to ensure such a flexibility, it is preferable not to rely on a preliminary partition of the domain (the socalled zonal approach), but rather on a continuous transition from one model to the other (the socalled continuous approach).
Various questions then arise: how can we improve the RANS models so as to accurately represent most of the physical phenomena in order to avoid having to switch to LES in large regions; how to play on the terms of the models, and on which criteria, to switch from RANS to LES; how to improve the robustness of the method to the choices made by the user (in particular the nearwall mesh). Our research work, described below, aims at answering these questions.
Today, even though the industrial demand for more accurate and robust RANS models is very significant, very few academic teams are active in this field (for instance, 85, 61, 35, 86), most of them being participants to the European ERCOFTAC SIG15 group of which we are an active member. In France, we collaborate with most of the teams, mainly in the industry (EDF, Dassault, PSA) or applied research organizations (ONERA, CEA). The CAGIRE team is particularly renowned for its work on the interaction between turbulence and the wall by elliptic blending (EBRSM, 67, 71), and is solicited by these partners to improve the representation of complex effects on turbulence (buoyancy, conjugate heat transfer, adverse pressure gradients, impingement, etc.).
Concerning the development of original hybrid RANS/LES approaches, the main contributions in France are due to ONERA (ZDES 47 and PITM 45); IMF Toulouse in collaboration with the ECUADOR team of the Inria center of SophiaAntipolis (OES 41, 78) and CAGIRE (HTLES 70, 3113, 20). The originality of our work lies in the concern to provide, through temporal filtering, a formally consistent link between the equations of motion and the hybridization method in order to reduce the level of empiricism, which is, for nonhomogeneous turbulence, along with the additive filter method 55, 30, one of only two methods capable of providing such a consistent framework.
3.2 Highorder numerical methods and efficient algorithms
When dealing with RANS models, a second order finite volume method is usually used. In our project, we aim at addressing hybrid RANS/LES models, which include some regions in which essentially unstationary processes are approximated in LES regions. This usually requires to use low dissipative high order numerical methods. If a consensus has emerged for years on second order finite volume methods for the approximation of RANS models, investigations are still ongoing on finding the high order method that would be the best suited with the compressible NavierStokes system.
As far as high order numerical methods are concerned, they are addressed at Inria essentially by the Atlantis, Makutu, Poems and Rapsodi teams for wavematter interaction problems, the Serena and Coffee projectteam on porous media, the Tonus team on plasma physics problems, and the Acumes, Gamma, Cardamom and Memphis teams for systems that are closer of ours (shallowwater or compressible Euler). As far as we know, only the Cardamom and Gamma teams are using high order methods with turbulence models, and we are the only one to aim at hybrid RANS/LES models with such methods.
Our objective is to develop a fast, stable and high order code for the discretization of compressible NavierStokes equations with turbulence models (Reynoldsstress RANS models and hybrid RANS/LES methods) on unstructured meshes. From a numerical point of view, this raises several questions: how to derive a stable numerical scheme for shocks without destroying the order of accuracy, how to derive stable boundary conditions, how to implement the method efficiently, how to invert the system if implicit methods are used?
Concerning aeronautical applications, several groups are working on discontinuous Galerkin methods: in Europe, some of the groups participated to the TILDA project 4 (DLR, ONERA, CERFACS, Imperial College, UCL, Cenaero, Dassault, U. of Bergamo). As far as we know, none of them considered Reynoldsstress RANS models or hybrid RANS/LES models. Worldwide, we believe the most active groups are the MIT group 5, or Ihme's group6 which is rather oriented on combustion. Concerning HPC for high order methods, we carefully follow the advances of the parallel numerical algorithm group at Virginia Tech, and also the work around PyFR at Imperial College. Both of these groups are considering imperative parallelism, whereas we have chosen to consider task based programming. Task based parallelism was considered in the SpECTRE code 65 based on the Charm++ framework, and within a European project7, based on IntelTBB, but only for hyperbolic systems whereas we wish to address the compressible NavierStokes system.
3.3 Development of specific numerical schemes
In this section, we are interested in two specific regimes of compressible flows: low Mach number flows and compressible multiphase flows.
Low Mach number flows (or low Froude for ShallowWater systems) are a singular limit, and therefore raise approximation problems. Two type of numerical problems are known: if convective time scales are considered, semiimplicit time integration is often preferred to explicit ones, because the acoustic CFL is very restrictive compared with the convective one in the low Mach number limit 48. The second numerical problem at low Mach number is an accuracy problem. The proposed fixes consist in changing the numerical flux either by centering the pressure 80 or are variant of the RoeTurkel fix 58. Over the last years, we have been more focused on the accuracy problem, but our major originality with respect to other groups is to be interested in the acoustic wave propagation in low Mach number flows, which may also raise problems as first remarked in 77.
Derivation of averaged compressible multiphase models is currently less active than in the 2000s, and only few teams are interested in such problems. Recent advances were made at RWTH 60, and also mostly in France at EDF R&D by J.M. Hérard or also by 43. This low interest in this type of challenging modeling and mathematical analysis was noticed in the review paper 83 as an obstacle for the improvement of numerical methods.
3.4 Analysis and simulation of turbulent flows and heat transfer
The numerous discussions with our industrial partners make it possible to define configurations to carry out comparison between computations and experiments aimed at validating the fundamental developments described in the previous sections. Reciprocally, the targeted application fields play an important role in the definition of our research axes, by identifying the major phenomena to be taken into account. This section gathers applications which essentially deal with turbulent internal flows, most often with heat transfer.
Detailed data are required for a fine validation of the methods. In addition to the active participation and coorganizing of the SIG15 group of the ERCOFTAC network, which gives us access to various experimental or DNS data and enables us to carry out model and code benchmarking exercises with other European teams 66, 73, 39, 69, our strategy is to generate experimental data ourselves when possible and to develop collaborations with other research groups when necessary (ONERA, institute Pprime, CEA).
Historically, the scientific convergence between the team members that led to the development of our project and the creation of the CAGIRE projectteam in 2016 was based on scientific themes related to aeronautical combustion chambers, with our industrial partners SAFRAN and Turbomeca (now SAFRANHelicopter Engines). If the scientific and application themes of the team are much more diverse, these applications to aeronautical combustors are at the origin of the existence of the MAVERIC experimental facility (which is in itself an originality within Inria), allowing the study of turbulent flows at low Mach number over multiperforated walls subjected to a coupling with acoustic waves, representative of the flows in combustors. This wind tunnel is thus complementary to those developed at ONERA, with which we collaborated 79 when it was necessary to add thermal measurements, within the framework of the European project SOPRANO.
4 Application domains
4.1 Aeronautics
Cagire is active in the field of aeronautics through the following activities:
 The combustion chamber wall: the modelling, the simulation and the experimentation of the flow around a multiperforated plate representative of a real combustion chamber wall are the three axes we have been developing during the recent period. The continuous improvement of our inhouse test facility Maveric is also an important ingredient to produce our own experimental validation data for isothermal flows. For nonisothermal flows, our participation in the EU funded program Soprano gave us access to nonisothermal data produced by Onera. This activity is also included in the E2SUPPA project Asturies.
 The flow around airfoils: the modelling of the turbulent boundary layer has been for almost a century a key issue in the aeronautics industry. However, even the more advanced RANS models face difficulties in predicting the influence of pressure gradients on the development of the boundary layer. A main issue is the reliability of the modelling hypotheses, which is crucial for less conservative design. One of the technological barriers is the prediction of the flow in regimes close to the edge of the flight domain (stall, buffeting, unsteady loads) when the boundary layer is slowed down by an adverse pressure gradient. This is the subject of the CIFRE PhD thesis of Gustave Sporschill, defended in 2021, in collaboration with Dassault Aviation.
 Impinging jets: because of their high heat transfer efficiency, turbulent impinging jets are commonly used in a large variety of applications, and in particular blade cooling systems. Understanding the underlying physics of the mechanisms at play is of prime interest and is still an open question. Additionally, this configuration remains a challenging test case for turbulence models since it embraces many flow features despite a relatively simple geometry, and causes strong discrepancies between standard turbulence closures. Reynolds stress transport models have been shown to be promising candidates but still suffer from a lack of validation regarding this flow configuration. Such models are the subject of a collaboration with Onera.
 Atmospheric reentry problem: When a body enters the atmosphere with a high velocity, its trajectory is mainly driven by the hypersonic flow surrounding the body. The integrity of the body is maintained by a shield that is progressively ablated. The sharp control of the motion is possible with a very good knowledge of the surrounding hypersonic flow and of its interaction with the ablated shield. Within the SEIGLE project, the team is involved in the simulation of the interaction of a droplet (representing the ablated body) and a hypersonic flow. In the Asturies project, the aim is to study the improvement on the shock/turbulence interaction by using advanced RANS models (secondmoment closure).
4.2 Energy
 The prediction of heat transfer in fluid and solid components is of major importance in power stations, in particular, nuclear power plants. Either for the thermohydraulics of the plenum or in the study of accidental scenarii, among others, the accurate estimation of wall heat transfer, mean temperatures and temperature fluctuations are necessary for the evaluation of relevant thermal and mechanical design criteria. The PhD thesis (CIFRE EDF) of G. Mangeon, was dedicated to the development of relevant RANS models for these industrial applications 74. The collaboration with EDF is pursued within the ANR project MONACO_2025 and via a new CIFRE PhD thesis under discussion.
 Moreover, the prediction of unsteady hydrodynamic loadings is a key point for operating and for safety studies of PWR power plants. Currently, the static loading is correctly predicted by RANS computations but when the flow is transient (as, for instance, in Reactor Coolant Pumps, due to rotor/stator interactions, or during operating transients) or in the presence of large, energetic, coherent structures in the external flow region, the RANS approach is not sufficient, whereas LES is still too costly for a wide use in the industry. This issue was the main focus of the recent PhD thesis (CIFRE EDF) of Vladimir Duffal, and is pursued within the ANR project MONACO_2025.
 For the design of high temperature solar receiver for concentrated solar power plants, flows are characterized by strong variations of the fluid properties, such that, even in the forced convection regime, they significantly deviate from isothermal flows, with a possible tendency to relaminarize, which can significantly reduce heat transfer. A better understanding and modeling of the physical mechanisms observed in turbulent flows with strong temperature gradients are important and was the focus of a recent collaboration with the LaTeP laboratory of UPPA 16.
 Thermal storage is interesting to decorrelate the production of heat or cold from its use whether for direct operation for a heat network (smoothing of heat supply to meet intermittent needs) or for power generation (phase shift between heat generation and power generation). The challenge is to study, via CFD, the dynamic and thermal behavior of the storage during the loading, resting and discharge phases. This is the focus of the PhD thesis of Alexis Ferré, cosupervised by R. Manceau and S. Serra (LaTeP) started in November 2020.
4.3 Automotive propulsion
 The engine (underhood) compartment is a key component of vehicle design, in which the temperature is monitored to ensure the effectiveness and safety of the vehicle, and participates in 5 to 8% of the total drag and CO2 emissions. Dimensioning is an aerodynamic and aerothermal compromise, validated on a succession of road stages at constant speed and stopped phases (red lights, tolls, traffic jam). Although CFD is routinely used for forced convection, stateoftheart turbulence models are not able to reproduce flows dominated by natural convection during stopped phases, with a Rayleigh number of the order of ${10}^{10}$, such that the design still relies on costly, fullscale, wind tunnel experiments. This technical barrier must be lifted, since the ambition of the PSA group is to reach a full digital design of their vehicles in the 2025 horizon, i.e., to almost entirely rely on CFD. This issue was the focus of the recent PhD thesis (CIFRE PSA) of S. Jameel, supervised by R. Manceau, and also a part of the ANR project MONACO_2025 described in section 10.2.1, in the framework of which S. Jameel was hired as a postdoc until July 2021.
 The Power & Vehicles Division of IFPEN codevelops a CFD code, CONVERGE, to simulate the internal flow in sparkignition engines, in order to provide the automotive industry with tools to optimize their design. The RANS method, widely used in the industry, is not sufficiently reliable for quantitative predictions, and is only used as a tool to qualitatively compare different geometries. On the other hand, LES provides more detailed and accurate information, but at the price of a CPU cost unafordable for daily use in the industry. Therefore, IFPEN aims at developing the hybrid RANS/LES methodology, in order to combine the strengths of the two approaches. The PhD thesis of Hassan Afailal, cosupervised by Rémi Manceau, was focused on this issue. In the framework of the juststarted collaborative project ASTURIES (E2SUPPA/Inria/CEA/IFPEN), this collaboration with IFPEN will be pursued by the development of highorder methods in the CONVERGE code in order to make it possible to perform highly accurate and lowdissipative LES and hybrid RANS/LES in combustion engines.
5 Social and environmental responsibility
Impact of research results
The availability of improved RANS models and hybrid RANS/LES methods offering a better physical representativeness than models currently used in the industry, at a reasonable computational cost, will make it possible to improve the reliability of industrial numerical simulations, and thus to better optimize the systems, in order to reduce the environmental impact of transportation and industrial processes, and to improve the safety of installations and reduce the risks of accidental pollution.
Moreover, previous applications of hybrid RANS/LES methods have shown that it is possible to obtain an accuracy equivalent to LES with an energy consumption of the simulation reduced by a factor of about 200. This gain can be considerably increased in a complete industrial simulation with a much higher Reynolds number, leading to a drastic reduction of the environmental impact of the simulations themselves.
6 Highlights of the year
Kevin Schmidmayer was hired on an ISFP position (permanent researcher position). He will join the CAGIRE team in April 2022. His arrival in the team will strengthen and extend the research themes in the direction of the advanced modelling and simulation of multiphase compressible flows, with medical and industrial applications.
A permanent Inria engineer position shared between the CAGIRE and CARDAMOM teams has been opened in 2021 to manage the software development of the Aerosol finite element library. Luca Cirrottola, a former non permanent engineer on the MMG meshing library will join the AeroSol development team in February 2022.
The ANR project Lagoon has been accepted. Coordinated by V. Perrier, it includes CAGIRE, CARDAMOM and the BRGM. It aims at improving implicit multigrid methods and large scale IO for near shore applications.
Beyond the opensource code Code_Saturne, developed by EDF 33, and the commercial code StarCCM+, the EBRSM RANS model developed by the team is now available in the codes Cedre of ONERA and Aether of Dassault Aviation.
The hybrid RANS/LES model HTLES, developed by the team, has been implemented in the commercial code Star CCM+, under the name SRH (ScaleResolving Hybrid), and has shown 75 its robustness and advantages over the most widely used method (DDES).
7 New software and platforms
7.1 New software
7.1.1 AeroSol

Keyword:
Finite element modelling

Functional Description:
The AeroSol software is a high order finite element library written in C++. The code has been designed so as to allow for efficient computations, with continuous and discontinuous finite elements methods on hybrid and possibly curvilinear meshes. The work of the team CARDAMOM (previously Bacchus) is focused on continuous finite elements methods, while the team Cagire is focused on discontinuous Galerkin methods. However, everything is done for sharing the largest part of code we can. More precisely, classes concerning IO, finite elements, quadrature, geometry, time iteration, linear solver, models and interface with PaMPA are used by both of the teams. This modularity is achieved by mean of template abstraction for keeping good performances. The distribution of the unknowns is made with the software PaMPA , developed within the team TADAAM (and previously in Bacchus) and the team Castor.

News of the Year:
In 2021, the development of the library was focused on the following points
* Development environment  Plugin : Uhaina, GeoFun, allow for plugins to register numerical schemes.  Time dependent data variables.  CI on Plafrim, intel compiler, Clang compiler
* General numerical feature of the library  Implementation of the Taylor finite element basis.  Implementation of the GaussLobatto finite element basis for quads and lines  Implementation of higher order derivatives into finite element basis.  CrouzeixRaviart, RannacherTurek nonconforming methods for the Laplace equation.  Dual consistent integration of source term involving gradients
* Work on SBM methods
* Low Mach number flows:  Implementation of the Euler and Waves models with porosity  initialization of a vector with a potential function.  Implementation of the BouchutChalonsGuisset numerical flux.  Low Mach number filtering.
* CG implementations:  Implementation of cubature elements with mass lumping  Development of the Continuous Interior Penalty method  parallel validation of CG
 URL:

Contact:
Vincent Perrier

Participants:
Benjamin Lux, Damien Genet, Mario Ricchiuto, Vincent Perrier, Héloïse Beaugendre, Subodh Madhav Joshi, Christopher Poette, Marco Lorini, Jonathan Jung, Enrique Gutierrez Alvarez, Anthony Bosco

Partner:
BRGM
8 New results
8.1 Turbulence modelling
8.1.1 Improvement of the EBRSM RANS model
Participants: Rémi Manceau, Gustave Sporschill.
External collaborators: F. Billard (Dassault), M. Mallet (Dassault), A. Colombié (ONERA), F. Chedevergne (ONERA), E. Laroche (ONERA), S. Benhamadouche (EDF), J.F. Wald (EDF).
In order accurately represent the complexity of the phenomena that govern the evolution of turbulent flows, an important part of our research focuses on the development of Reynoldsstress RANS models that take into account the wall/turbulence interaction by an original approach, elliptic blending 67, 71. Although this approach, has been successfully applied to various configurations (for instance 38), in order to take into account more subtle effects, during the theses of A. Colombié and G. Sporschill, in collaboration with ONERA and Dassault Aviation, respectively, we identified the importance of introducing a specific pressure diffusion model to correctly reproduce the dynamics of turbulence in impingement regions and in boundary layers subject to adverse pressure gradients, paving the way towards a wider application of the EBRSM in aeronautics 27, 10, 25.
8.1.2 Extension of RANS turbulence models to mixed and natural convection
Participants: Rémi Manceau, Puneeth Bikkanahally, S.M. Saad Jameel.
External collaborators: V. Herbert (PSAStellantis), S. Benhamadouche (EDF).
In the mixed and natural convection regimes, as presented in two invited lectures 68, 69, the interaction mechanisms between dynamic and thermal fluctuations are complex and very anisotropic due to buoyancy effects, so that the natural turbulence modelling level to take them into account is secondmoment closure, i.e., Reynoldsstress models. When associating the EBRSM and the EBDFM, several modifications had to be introduced in natural convection for the scrambling term, the length scale of the elliptic blending, and especially by substituting a mixed time scale for the dynamic time scale in the buoyancy production term of the dissipation equation, which has a drastic positive impact on the predictions in the natural convection regime. This work, carried out in collaboration with EDF, leads to the first linear Reynoldsstress model able to accurately represent the wall/turbulence interaction in forced, mixed and natural convection regimes 49. However, some industrial partners, in particular PSA Group (now Stellantis), who encounter natural convection flows in the underhood compartment of vehicles, do not wish to use such sophisticated models, so we have developed an algebraic version of the Reynolds stress equation which thus constitutes an extension of the eddyviscosity models (buoyancyextended Boussinesq relation), within the framework of S. Jameel thesis 64, 63, 62, which can be easily implemented into any industrial and/or commercial CFD code.
8.1.3 HTLES: an original hybrid RANS/LES model
Participants: Rémi Manceau, Puneeth Bikkanahally, Mahitosh Mehta.
External collaborators: Vladimir Duffal (EDF), B. de Laage de Meux (EDF), H. Afailal (formerly CAGIRE/IFPEN, now Framatome), Ch. Angelberger (IFPEN), A. Velghe (IFPEN).
Regarding hybrid RANS/LES, we have developed the HTLES (hybrid temporal LES) approach. The wall/turbulence interaction being fundamental for the applications of interest to EDF, V. Duffal's thesis 51 focused on the precise control of the transition from RANS to LES when moving away from the wall, through the improvement of the theoretical link between the turbulent scales and the form of the model equations, as well as the introduction of two different shielding functions to avoid the classical gridinduced separation and loglayer mismatch 13, 17, i.e., the strong erroneous sensitivity of the results to the nearwall mesh. A significant result is that the study of wall pressure fluctuations and their spectra on periodic hills showed that the HTLES approach could reproduce these spectra as well as LES, down to a lower cutoff frequency than in LES due to the coarser mesh and the presence of the RANS zone 51, which suggests encouraging prospects for the prediction of mechanical and thermal fatigue. In the framework of the ANR project Monaco_2025, the thesis of P. Bikkanahally is devoted to the extension of the HTLES approach to natural convection. In differentially heated cavities, due to the coexistence of turbulent boundary layers and a laminar region in the centre, the shielding function introduced by V. Duffal causes a deterioration of the results. Good results are obtained by using instead a new shielding function based on the resolution of an elliptic relaxation equation 23, 20. Finally, the thesis of H. Afailal, in collaboration with IFPEN, was dedicated to the development of the HTLES for the nonreactive internal aerodynamics of spark ignition engines. The aim was to adapt this approach to nonstationary, cyclic flows with moving walls, for which the main challenge was to provide a reliable evaluation of the mean turbulent energy, which is a crucial parameter for the control of the transition from RANS to LES, and is obtained by explicitly applying a differential temporal filter during the simulation to separate the timedependent mean and turbulent components of the flow 32.
8.2 Highorder numerical methods and efficient algorithms
8.2.1 Improvement of scalability through taskbased programming
Participants: Vincent Perrier, Jonathan Jung.
External collaborators: M. Haefele (LMAP), Storm projectteam, Hiepacs projectteam.
Task based programming has emerged over about a decade as an alternative to classical imperative parallel programming based on MPI or on coarse grain OpenMP, since it provides more flexibility for addressing heterogeneous architectures. Task based programming has began entering the OpenMP standard since the 4.0 version, but still remains in specific libraries such as OMPss 52, Parsec 40 or StarPU 34 for their most advanced features. In 53, we have developed a two dimensional mockup code for the first order finite volume approximation of the Euler system on structured meshes based on StarPU, yielding interesting results; for example, for a mesh partitioned into $N$ parts, the code may scale with more than $N$ cores; another example is the possibility to temporarily allocate a resource to IO and to use it again for computation once the IO is finished. Since 2019, S. Simon started his postdoc under the cosupervision of J. Jung, M. Haefele and V. Perrier for extending the mockup code to second order finite volume, and to the three dimensional discontinuous Galerkin method for the compressible NavierStokes system. Within this project, we are also developing roofline models for analyzing the different algorithms and try to explain their behaviour with respect to the architecture addressed.
8.3 Development of specific numerical schemes
8.3.1 LowMachnumber schemes
Participants: Pascal Bruel, Jonathan Jung, Vincent Perrier, Ibtissem Lannabi.
External collaborators: E. Dick (Ghent University), Y. Moguen (SIAME, UPPA), S. Dellacherie (HydroQuébec), P. Omnes (CEA, LAGA).
In 76, the last developments of a pressurecorrection algorithm for compressible fluid flow regimes were presented. It is wellsuited to simulate flows at all levels of Mach number with smooth and discontinuous flow parameter changes, by providing a precise representation of convective transport and acoustic propagation. A colocated finite volume space discretization was used with the AUSM flux splitting. It was demonstrated that two ingredients are essential for obtaining goodquality solutions: the presence of an inertia term in the face velocity expression and a velocity difference diffusive term in the face pressure expression, with a correct Mach number scaling to recover the hydrodynamic and acoustic low Mach number limits. To meet these two requirements, a new flux scheme, named MIAU, for Momentum Interpolation with Advection Upstream splitting was proposed.
In 11, a numerical scheme and a low Mach number fix for a system with a nonconservative source term due to porosity variation was proposed and tested. The problem was understood on the linear wave equation with porosity and based on the linear study, a scheme for the nonlinear and nonconservative case has been proposed.
In 44, the behaviour of acoustic waves in low Mach number flows was investigated. It was found that classical low Mach number fixes fail at propagating acoustic waves at high order: either the scheme damps acoustic waves because it is not asymptotically consistent with low Mach number acoustics, or a loss of convergence order is observed for DG schemes at second order. A fix was proposed, which allows to recover the optimal order of convergence for low Mach number acoustics.
Unfortunately, the only fix we found in 44 that is accurate for high order acoustics computation is not Galilean invariant. This led us to try to tackle the problem in a different way than the numerical flux modification. We raised more fundamental questions on the connection between the low Mach number spurious mode responsible for a low accuracy and the long time behaviour of the wave system. In 14, we proved that on some finite domain configurations, the long time limit of the wave system exists, and that a numerical flux is low Mach number accurate if and only if its low Mach number acoustic development has a consistent long time behaviour. The spurious mode on the velocity at low Mach number can therefore be identified as the nondivergencefree part of the long time limit of the asymptotic acoustic system. Once this spurious mode is sharply identified, it can be filtered, which we did in an article currently in review. From an inaccurate solution, an accurate solution can be obtained by solving a Laplace equation, see 26. Last, we proved that a known result on finite volume schemes, namely the accuracy of the Roe scheme on triangular meshes 57 holds also for discontinuous Galerkin methods 26.
8.3.2 Artificial compressibility method for Mach zero combustion
Participants: Pascal Bruel.
External collaborators: C. Cristaldo (Universidade Federal do Pampa, Brazil), M. Donini (INPE, Brazil), F. Fachini (INPE, Brazil).
As a first step towards the simulation of low Mach reacting flows, an efficient methodology to simulate variable density flows in the Mach zero limit, either inert or reacting was developed. The approach combined a finite volume framework on fully staggered grids with the artificial compressibility method and a dualtime stepping. The resulting code proved to be versatile enough to cope with excellent accuracy with flow configurations ranging from unsteady cylinder wakes to unsteady laminar diffusion flames 12.
8.3.3 Multiphase flows
Participants: Vincent Perrier.
As far as multiphase models are concerned, based on the ideas of 50, we have revisited the derivation of BaerandNunziato models 36. Usually, models are derived by averaging the Euler system; then the system of PDE on the mean values contains fluctuations which are modeled, often leading to relaxation terms and interfacial velocity and pressure which should also be modeled. This can be achieved by using physical arguments 82 or by ensuring mathematical properties 46. In 15, we have followed a slightly different path: we have supposed that the topology of the different phases follows an explicit model: the sign of a Gaussian process. Some parameters of the Gaussian process (mean, gradient of the mean) are linked with the averaged values of the flow (volume fraction), whereas others (autocorrelation function) are linked with the subscale structure of the flow. The obtained system is closed provided the parameters of the Gaussian process are known. Also, the system dissipates the phasic entropies. Under some hypothesis that can be interpreted physically, asymptotic models can be derived in the interface flow limit or in the limit where the two fluids are strongly mixed. In these limits, different previously proposed models are recovered 82, 54, which does not necessarily ensure the same phasic entropy dissipation properties.
8.4 Analysis and simulation of turbulent flows and heat transfer
8.4.1 Modelling of solar receivers
Participants: Rémi Manceau.
External collaborators: S. Serra (LaTEP, UPPA), E. Franquet (formerly LaTEP, UPPA, now Univ. Côte d'Azur).
In collaboration with the LaTEP laboratory of Pau, we have extended the validation of the EBRSM model to flows encountered in the solar receivers of concentrated solar power plants with very large temperature differences between two walls, such that variations of the molecular viscosity can lead to relaminarization 84. This work, which demonstrated the ability of the EBRSM model to reproduce these effects 42, allowed a broad parametric study to determine physical criteria to guide the design of future solar receivers 16.
8.4.2 Effusion cooling
Participants: Rémi Manceau, Pascal Bruel.
External collaborators: Ph. Reulet (ONERA), E. Laroche (ONERA), D. Donjat (ONERA), F. Mastrippolito (formerly CAGIRE, now GDTech France).
As regards wall cooling by effusion (multiple jets in crossflow), our MAVERIC experimental facility does not allow us to carry out thermal measurements, so we approached ONERA Toulouse to collaborate on the effects of gyration (angle of the jets with respect to the incident flow) on the heat transfer between the fluid and the wall, within the framework of the European project SOPRANO. We then took up the challenge of carrying out RANS simulations with the EBRSM model on a configuration of unprecedented complexity for us, consisting of 10 rows of 9 holes, in 90degree gyration, representative of effusion cooling problems in aeronautical combustion chambers. Comparisons between calculations and experiments have shown the relevance of using the EBRSM model and the importance of taking into account conjugate heat transfer 79.
8.4.3 Security of reservoirs and pipelines
Participants: Pascal Bruel.
External collaborators: S. Elaskar (University of Cordoba, Argentina), J. Saldia (University of Cordoba, Argentina), L. Gutiérrez Marcantoni (University of Cordoba, Argentina), A. Beketaeva (Institute of Mathematics and Mathematical Modelling, Almaty, Kazakhstan), A. Naimanova (Institute of Mathematics and Mathematical Modelling, Almaty, Kazakhstan).
In the framework of the cooperation with our international partners in Kazakhstan and Argentina, simulations of turbulent flows in different configurations were performed. The flow configurations ranged from the injection of a sonic jet in a supersonic crossflow 37, the interaction of an atmospheric boundary layer with aerial reservoir(s) 81 or of a channel flow with cylinders in tandem 56 to the simulation of a blast wave of Sedovlike type 59. The objectives of these simulations were twofold: 1) Assessing the predictive capabilities of conventional RANS approaches by comparisons with experimental data in order to establish the margin of progression that could be subsequently brought about by the recourse to the more elaborated turbulence models developed by our team and 2) Providing a knowledge of the sensitivity of the different flow topologies and characteristics to the variation of the relevant parameters describing the different configurations at hand. In parallel, our test facility MAVERIC was upgraded in order to accompany the forthcoming validation activities in the framework of the ASTURIES project and the partnership with our Argentinian colleagues.
8.4.4 Thermocline energy storage
Participants: Rémi Manceau, Alexis Ferré.
External collaborators: S. Serra (LaTEP, UPPA), J. Pouvreau (CEA), A. Bruch (CEA).
Finally, a collaboration started at the end of 2020 with the CEA LITEN in Grenoble and the LaTEP of UPPA on thermocline energy storage. An experimental facility is being developed at the CEA and RANS simulations are underway to understand the dynamics of this type of flows, to determine the influence of the turbulence generated by the filling of the tank on the quality of the thermocline, in order to optimize the system and provide data to support the development of 1D models used in the optimization of heat networks.
9 Bilateral contracts and grants with industry
Participants: Rémi Manceau, Vincent Perrier, Jonathan Jung, Pascal Bruel, Gustave Sporschill, Anthony Bosco, Mahitosh Mehta, Romaric Simo Tamou, Alexis Ferré.
9.1 Bilateral contracts with industry
 Dassault Aviation: "Improvement of the turbulence models”, contract associated to the PhD thesis of Gustave Sporschill.
 CEA: “Agile simulation of turbulent internal flows”, contract in the framework of the Asturies project.
 CEA: “Collaboration contract for the PhD thesis of A. Ferré".
9.2 Bilateral grants with industry
 Dassault Aviation (Cifre PhD grant): "Improvement of the turbulence models. Application to the prediction of aerodynamic flows", PhD student Gustave Sporschill.
 CEA: “CFD and experimental study of a thermoclinetype thermal storage for an optimized design and data entry of component scale models in the framework of a multiscale approach”, PhD student Alexis Ferré.
 CEA: “Development of Fast, Robust and Accurate numerical methods for turbulence models on Complex Meshes” (1/2 Grant), PhD student Anthony Bosco.
10 Partnerships and cooperations
10.1 European initiatives
10.1.1 FP7 & H2020 projects
Participants: Pascal Bruel, Rémi Manceau.
 Topic: MG1.22015  Enhancing resource efficiency of aviation
 Project acronym: SOPRANO
 Project title: Soot Processes and Radiation in Aeronautical inNOvative combustors
 Duration: 01/09/2016  28/02/2021
 Coordinator: SAFRAN
 Other partners:
 France: CNRS, CERFACS, INSA Rouen, SAFRAN SA, Snecma SAS, Turbomeca SA.
 Germany: DLR, GEDE Gmbh, KIT, MTU, RRD,
 Italy: GE AVIO SRL, University of Florence
 United Kingdom: Rolls Royce PLC, Imperial College of Science, Technology and Medecine, Loughborough University.
 Abstract:
For decades, most of the aviation research activities have been focused on the reduction of noise and NOx and
CO2 emissions. However, emissions from aircraft gas turbine engines of nonvolatile PM, consisting primarily of
soot particles, are of international concern today. Despite the lack of knowledge toward soot formation processes
and characterization in terms of mass and size, engine manufacturers have now to deal with both gas and particles
emissions. Furthermore, the understanding of heat transfer, that is also influenced by soot radiation, is an important matter
for the improvement of the combustor's durability, as the key point when dealing with lowemissions combustor
architectures is to adjust the air flow split between the injection system and the combustor's walls. The SOPRANO
initiative consequently aims at providing new elements of knowledge, analysis and improved design tools, opening the
way to:
 Alternative designs of combustion systems for future aircrafts that will enter into service after 2025 capable of simultaneously reducing gaseous pollutants and particles,
 Improved liner lifetime assessment methods. Therefore, the SOPRANO project will deliver more accurate experimental and numerical methodologies for predicting the soot emissions in academic or semitechnical combustion systems. This will contribute to enhance the understanding of soot particles formation and their impact on heat transfer through radiation. In parallel, the durability of cooling liner materials, related to the wall air flow rate, will be addressed by heat transfer measurements and predictions. Finally, the expected contribution of SOPRANO is to apply these developments in order to determine the main promising concepts, in the framework of current lowNOx technologies, able to control the emitted soot particles in terms of mass and size over a large range of operating conditions without compromising combustor's liner durability and performance toward NOx emissions.
 In the SOPRANO project, our objective is to complement the experimental (ONERA) and LES (CERFACS) work by RANS computations of the flow around a multiperforated plate. Franck Mastrippolito, the postdoc recruited from midjanuary 2019 to midjanuary 2020, performed simulations aimed at reproducing the experiment of ONERA Toulouse carried out in the same workpackage. The configuration is that of an effusion plate with a gyration angle of 90 degrees and the turbulence model is EBRSM.
10.2 National initiatives
10.2.1 ANR MONACO_2025
Participants: Rémi Manceau.
The ambition of the MONACO_2025 project, coordinated by Rémi Manceau, is to join the efforts made in two different industrial sectors in order to tackle the industrial simulation of transient, turbulent flows affected by buoyancy effects. It brings together two academic partners, the projectteam Cagire hosted by the university of Pau, and the institute Pprime of the CNRS/ENSMA/university of Poitiers (PPRIME), and R&D departments of two industrial partners, the PSA group and the EDF group, who are major players of the automobile and energy production sectors, respectively.
 The main scientific objective of the project is to make a breakthrough in the unresolved issue of the modelling of turbulence/buoyancy interactions in transient situations, within the continuous hybrid RANS/LES paradigm, which consists in preserving a computational cost compatible with industrial needs by relying on statistical approaches where a finegrained description of the turbulent dynamics is not necessary. The transient cavity flow experiments acquired during MONACO_2025 will provide the partners and the scientific community with an unrivalled source of knowledge of the physical mechanisms that must be accounted for in turbulence models.
 The main industrial objective is to make available computational methodologies to address dimensioning, reliability and security issues in buoyancyaffected transient flows. It is to be emphasized that such problems are not tackled using CFD at present in the industry. At the end of MONACO_2025, a panel of methodologies, ranging from simple URANS to sophisticated hybrid model based on improved RANS models, will be evaluated in transient situations, against the dedicated cavity flow experiments and a real car underhood configuration. This final benchmark exercise will form a decisionmaking tool for the industrial partners, and will thus pave the way towards highperformance design of lowemission vehicles and highly secure power plants. In particular, the project is in line with the Full Digital 2025 ambition, e.g., the declared ambition of the PSA group to migrate, within the next decade, to a design cycle of new vehicles nearly entirely based on CAE (computer aided engineering), without recourse to expensive fullscale experiments.
10.3 Regional initiatives
10.3.1 SEIGLE
Participants: Jonathan Jung, Vincent Perrier.
SEIGLE means "Simulation et Expérimentation pour l'Interaction de Gouttes Liquides avec un Ecoulement fortement compressible". It is a 3year program which started in October 2017 and is funded by Région NouvelleAquitaine, ISAEENSMA, CESTA and Inria. The interest of understanding aerodynamic mechanisms and liquid drop atomization is explained by the field of applications where they play a key role, specially in the new propulsion technologies through detonation in the aerospace as well as in the securities field. The SEIGLE project was articulated around a triptych experimentation, modeling and simulation. An experimental database will be constituted. It will rely on a newly installed facility (Pprime), similar to a supersonic gust wind tunnel/ hypersonic from a gaseous detonation tube at high pressure. This will allow to test modeling approaches (Pprime / CEA) and numerical simulation (Inria / CEA) with high order schemes for multiphasic compressible flows, suitable for processing shock waves in twophase media.
10.3.2 HPC scalable ecosystem
Participants: Jonathan Jung, Vincent Perrier, Sangeeth Simon.
HPC scalable ecosystem is a 3year program funded by Région NouvelleAquitaine (call 2018), Airbus, CEACESTA, University of Bordeaux, INRA, ISAEENSMA and Inria. Sangeeth Simon was hired as a postdoc with the objective of extending the prototype code developed in 53 to high order (discontinuous Galerkin) and nonreactive diffusive flows in 3D. The same basis will be developed in collaboration with Pprime for WENO based methods for reactive flows.
10.3.3 ASTURIES
Participants: Rémi Manceau, Vincent Perrier, Jonathan Jung, Pascal Bruel, Anthony Bosco, Mahitosh Mehta, Romaric Simo Tamou.
Call: ISite E2S UPPA "Exploring new topics and facing new scientific challenges for Energy and Environment Solutions"
Dates: 20202024
Partners: CEA CESTA ; IFPEN
In the context of internal turbulent flows, relevant to aeronautic and the automotive propulsion and energy production sectors, ASTURIES aims at developing an innovative CFD methodology. The next generation of industrial CFD tools will be based on the only approach compatible with admissible CPU costs in a foreseeable future, hybrid RANS/LES. However, stateoftheart hybrid RANS/LES methods suffer from a severe limitation: their results are strongly userdependant, since the local level of description of the turbulent flow is determined by the mesh designed by the user.
In order to lift this technological barrier, an agile methodology will be developed: the scale of description of turbulence will be locally and automatically adapted during the computation based on local physical criteria independent of the grid step, and the mesh will be automatically refined in accordance. Such an innovative approach requires the use of advanced nearwall turbulence closures, as well as highorder numerical methods for complex geometries, since lowdissipative discretization is necessary in LES regions. Morevover, the identification of relevant physical RANStoLES switchover criteria and the refined validation of the method will strongly benefit from dedicated experiments.
The objectives of the project thus consist in:
 Proposing a robust and efficient implementation of elliptic relaxation/blending turbulence models in the context of highorder Discontinuous Galerkine methods.
 Develop local physical criteria in order to get rid of the (explicit or implicit) dependence on the grid step of the transition from RANS to LES.
 Develop an automatic remeshing strategy which ensures consistency with the selfadaptation of the model.
 Validate the global methodology based on the 3 preceding points for configurations representative of industrial internal turbulent flows.
The development of such a methodology, based on hybrid RANS/LES modelling, with lowdissipative and robust numerical methods, independant of the initial design of a grid by the user, compatible with unstructured meshes for complex industrial geometries, in the context of HPC, is thus the ambitious, but reachable, objective of the project.
11 Dissemination
Participants: Rémi Manceau, Pascal Bruel, Jonathan Jung, Vincent Perrier.
11.1 Promoting scientific activities
Member of the conference program committees
 Member of the scientific committee of the International Symposium on Turbulence, Heat and Mass Transfer since 2006 [Rémi Manceau]
11.1.1 Journal
Member of the editorial boards
 Advisory Board of International Journal of Heat and Fluid Flow [Rémi Manceau]
 Advisory Board of Flow, Turbulence and Combustion [Rémi Manceau]
Reviewer  reviewing activities
 Int. J. Heat Fluid Flow (2) [Rémi Manceau]
 Phys. Fluids [Rémi Manceau]
 Flow, Turbulence and Combustion [Rémi Manceau]
 Nuclear Enginering and Design [Rémi Manceau]
 Continuum Mechanics and Thermodynamics [Jonathan Jung]
 Aerospace Science and Technology (2) [Pascal Bruel]
 Revista Facultad de Ingenieria de la Universidad de Antoquia (2) [Pascal Bruel]
11.1.2 Invited talks
23 R. Manceau and P. Bikkanahally. ‘Hybrid Temporal LES: from theory to applications’. In: HiFiLeD  2nd High Fidelity Industrial LES/DNS Symposium. Toulouse / Virtual, France, 22nd Sept. 2021.
24 V. Perrier. ‘Stochastic derivation of BaerandNunziato models: homogenization of twophase hyperbolic terms and discussions on other cases’. In: Third workshop on compressible multiphase flows Strasbourg. Strasbourg, France, 21st June 2021.
21 J. Jung. ‘Méthode de volumes finis pour la mécanique des fluides compressibles et problèmes de précision à bas nombre de Mach’. In: Journées d’inauguration de la fédération MARGAUx. La Rochelle, France, 28th June 2021.
11.1.3 Leadership within the scientific community
 R. Manceau has been a member of the Standing committee of the Special Interest Group Turbulence modelling (SIG15) of ERCOFTAC since 2005, together with 9 other committee members (S. Jakirlić [chairman], F. Menter, S. Wallin, D. von Terzi , B. Launder, K. Hanjalić, W. Rodi, M. Leschziner, D. Laurence). The main activities of the group is to organize international workshops and thematic sessions in international congresses.
 Rémi Manceau coordinates the ANR Project MONACO_2025, a 4year project started in 2018. The partners are: the institute PPrime, PSA Group and EDF.
 Rémi Manceau coordinates the 4year E2SUPPA project ASTURIES, which involves CEA and IFPEN.
11.1.4 Research administration
 Coresponsible for the organisation of the LMAP seminar of Mathematics and their Applications [Jonathan Jung].
 Member of the LMAP council [Jonathan Jung, Pascal Bruel].
 Member of the IPRA research federation scientific council [Rémi Manceau].
 Member of the CDT, in charge of the evaluation of software projects at the Inria Bordeaux center [Vincent Perrier].
 Elected member of the Inria evaluation committee and member of the board [Vincent Perrier]. 8
 Member of the CT3Num committee of Pau University, in charge of managing the computing resources and projects at Pau University [Vincent Perrier].
11.2 Teaching  Supervision  Juries
(Legend: L1L2L3 corresponds to the 3 years of undergraduate studies, leading to the BSc degree; M1M2 to the 2 years of graduate studies, leading to the MSc degree; E1E2E3 to the 3 years of engineering school, equivalent to L3M1M2, leading to the engineer/MSc degree)
11.2.1 Responsabilities in teaching
 In charge of the L2 of the MathematicsComputer Science BSc [Jonathan Jung]
 In charge of the L2 of the cursus Master in Engineering program Mathematics and Computer Science [Jonathan Jung]
 In charge of the L3 of the cursus Master in Engineering program Mathematics and Computer Science [Jonathan Jung]
 In charge of the M1 of the cursus Master in Engineering program Mathematics and Computer Science [Jonathan Jung]
 In charge of the M2 of the cursus Master in Engineering program Mathematics and Computer Science [Jonathan Jung]
11.2.2 Teaching
 L1 [J. Jung]: Research and innovation, 1.5h/year, Université de Pau et des Pays de l'Adour, Pau, France.
 L2 [J. Jung]: Numerical analysis for vectorial problems, 42.75h/year, Mathematics, Université de Pau et des Pays de l'Adour, Pau, France.
 M1 [J. Jung]: Tools for scientific computing, 48h75/year, MMS, Université de Pau et des Pays de l'Adour, Pau, France.
 M2 [J. Jung, V. Perrier]: Finite volume scheme for hyperbolic systems, 24h/year, MMS, Université de Pau et des Pays de l'Adour, Pau, France.
 M1 [J. Jung]: Supervised personal work, 5 h/year, MMS, Université de Pau et des Pays de l'Adour, Pau, France.
 M2: [V. Perrier], Finite volume scheme for hyperbolic systems, Master MMS, Pau. 24h/year.
 M2 [R. Manceau]: Turbulence modelling (in English), 27h30/year, International Master program Turbulence, ISAEENSMA/École centrale de Lille, France.
 E3 [R. Manceau]: Industrial codes for CFD (in English), 12h30/year, ISAEENSMA, Poitiers, France CITATION NOT FOUND: manceau:hal03207431.
 E3 [R. Manceau]: Advanced physics–Turbulence modelling for CFD, 16h/year, ENSGTI, France 29.
11.2.3 Supervision
 PhD defended in 2021: Gustave Sporschill, “Improved ReynoldsStress Modeling for AdversePressureGradient Turbulent Boundary Layers in Industrial Aeronautical Flow", Dassault Aviation, Rémi Manceau.
 PhD in progress: Puneeth Bikkanahally Muni Reddy, “Modelling turbulent flows in natural convection regimes using hybrid RANSLES approaches”, UPPA, ANR project Monaco_2025, Rémi Manceau.
 PhD in progress: Mahitosh Mehta, “Development of an agile methodology for hybrid RANSLES computations of turbulent flows”, UPPA, E2SUPPA Asturies project, Rémi Manceau
 PhD in progress: Romaric Simo Tamou, “Development of highorder methods in a Cartesian AMR/Cutcell code. Application to LES modelling of combustion”, IFPEN, E2SUPPA Asturies project, Vincent Perrier.
 PhD in progress: Anthony Bosco, “Development of Fast, Robust and Accurate numerical methods for turbulence models on Complex Meshes” CEA/E2SUPPA, E2SUPPA Asturies project, Vincent Perrier and Jonathan Jung.
 PhD in progress: Alexis Ferré, “CFD and experimental study of a thermoclinetype thermal storage for an optimized design and data entry of component scale models in the framework of a multiscale approach”, CEA LITEN, Rémi Manceau.
 PhD in progress: Ibtissem Lannabi , “Discontinuous Galerkin methods for low Mach flows in fluid mechanics”, EDENE project (H2020 MarieSklodowskaCurie COFUND), Jonathan Jung and Vincent Perrier.
11.2.4 Juries
 Referee: Mohamed Yacine Ben Ali, PhD thesis, University Rennes 1 [Rémi Manceau]
 Referee: Yann Marchenay, PhD thesis, University of Toulouse [Rémi Manceau]
 President of the jury: Martin Thomas, PhD thesis, University of Toulouse [Pascal Bruel]
 Referee: Emmanuel Laroche, HDR, University of Toulouse [Pascal Bruel]
 Member: Mariovane Donini, PhD thesis, INPE (Brazil) [Pascal Bruel]
11.3 Popularization
11.3.1 Interventions
Vincent Perrier animated a debate around the release of the movie "Adventures Of A Mathematician".
12 Scientific production
12.1 Major publications
 1 articleA low Mach correction able to deal with low Mach acoustics.Journal of Computational Physics3782019, 723759
 2 articleConstruction of modified Godunov type schemes accurate at any Mach number for the compressible Euler system.Mathematical Models and Methods in Applied SciencesNovember 2016
 3 articleDevelopment and Validation of a new formulation of Hybrid Temporal Large Eddy Simulation.Flow, Turbulence and Combustion2021
 4 articleLES fluidsolid coupled calculations for the assessment of heat transfer coefficient correlations over multiperforated walls.Aerospace Science and Technology532016, 13
 5 articleRungeKutta discontinuous Galerkin method for the approximation of Baer and Nunziato type multiphase models.Journal of Computational Physics23111February 2012, 40964141
 6 articleAn interface condition to compute compressible flows in variable cross section ducts.Comptes Rendus MathématiquesFebruary 2016
 7 articleRecent progress in the development of the Elliptic Blending Reynoldsstress model.Int. J. Heat Fluid Fl.512015, 195220URL: http://dx.doi.org/10.1016/j.ijheatfluidflow.2014.09.002
 8 articleExtension to various thermal boundary conditions of the elliptic blending model for the turbulent heat flux and the temperature variance.Journal of Fluid Mechanics905A1December 2020, 134
 9 articleGodunovtype schemes with an inertia term for unsteady full Mach number range flow calculations.Journal of Computational Physics281January 2015, 35
12.2 Publications of the year
International journals
 10 articleLargeeddysimulationbased analysis of Reynoldsstress budgets for a round impinging jet.Physics of Fluids3311November 2021, 115109
 11 articleConstruction of a low Mach finite volume scheme for the isentropic Euler system with porosity.ESAIM: Mathematical Modelling and Numerical Analysis553June 2021, 1199  1237
 12 articleAn Artificial Compressibility Based Approach to Simulate Inert and Reacting Flows.Journal of Fluid Flow, Heat and Mass Transfer2021
 13 articleDevelopment and Validation of a new formulation of Hybrid Temporal Large Eddy Simulation.Flow, Turbulence and Combustion2021
 14 articleLong time behavior of finite volume discretization of symmetrizable linear hyperbolic systems.IMA Journal of Numerical AnalysisDecember 2021
 15 articleDerivation and Closure of Baer and Nunziato Type Multiphase Models by Averaging a Simple Stochastic Model.Multiscale Modeling and Simulation: A SIAM Interdisciplinary Journal191January 2021, 401439
 16 articleAsymmetric reverse transition phenomenon in internal turbulent channel flows due to temperature gradients.International Journal of Thermal Sciences1591064632021
International peerreviewed conferences
 17 inproceedingsA new formulation of hybrid temporal largeeddy simulation.ETMM 2021  13th International ERCOFTAC symposium on engineering, turbulence, modelling and measurementsRhodes / Virtua, GreeceSeptember 2021
 18 inproceedingsTurbulence modelling improvements for APG flows on industrial configurations.55th 3AF International Conference on Applied Aerodynamics (AERO2020+1)Poitiers (Virtual), FranceMarch 2021
National peerreviewed Conferences
 19 inproceedingsImplementation and validation of a secondmoment RANS turbulence model in OpenFOAM ®.MECOM 2021  37° Congreso Argentino de Mecánica ComputacionalResistencia, ArgentinaNovember 2021
Conferences without proceedings
 20 inproceedingsDevelopment of a hybrid RANSLES model based on temporal filtering for natural convection flows.WCCM  14th World Congress in Computational Mechanics, ECCOMAS Congress 2020Virtual, France2021
 21 inproceedingsMéthode de volumes finis pour la mécanique des fluides compressibles et problèmes de précision à bas nombre de Mach.Journées d'inauguration de la fédération MARGAUxLa Rochelle, FranceJune 2021
 22 inproceedingsUne méthode de filtrage pour les écoulements à faible nombre de Mach.10ème biennale française des mathématiques appliquées et industriellesLa Grande Motte, FranceJune 2021
 23 inproceedingsHybrid Temporal LES: from theory to applications.HiFiLeD  2nd High Fidelity Industrial LES/DNS SymposiumToulouse / Virtual, FranceSeptember 2021
 24 inproceedingsStochastic derivation of BaerandNunziato models: homogenization of twophase hyperbolic terms and discussions on other cases.Third workshop on compressible multiphase flows StrasbourgStrasbourg, FranceJune 2021
 25 inproceedingsReynolds stress RANS models for industrial aeronautical applications.WCCMECCOMAS Congress  14th World Congress in Computational Mechanics and ECCOMAS CongressParis / Virtual, FranceJanuary 2021
Doctoral dissertations and habilitation theses
 26 thesisContributions to the high order approximation of compressible flows: multiphase flows, low Mach number flows.Université de Pau et des Pays de l'Adour (UPPA), Pau, FRA.June 2021
 27 thesisImproved ReynoldsStress Modeling for AdversePressureGradient Turbulent Boundary Layers in Industrial Aeronautical Flow.Université de Pau et des Pays de l'AdourJune 2021
12.3 Other
Educational activities
 28 unpublishedModelisation de la turbulence pour la CFD.October 2021, MasterFrance
 29 unpublishedTurbulence modelling for CFD.October 2021, MasterFrance
12.4 Cited publications
 30 inproceedingsA RANS assisted LES approach.Direct and LargeEddy Simulation XI25ERCOFTAC SeriesSpringer, Cham2019, 159165
 31 articleDevelopment and validation of a hybrid temporal LES model in the perspective of applications to internal combustion engines.Oil & Gas Science and Technology  Revue d'IFP Energies nouvelles742019, 56
 32 phdthesisNumerical simulation of nonreactive aerodynamics in Internal Combustion Engines using a hybrid RANS/LES approach.Université de Pau et des Pays de l'AdourDecember 2020
 33 articleCode Saturne: A Finite Volume Code for the Computation of Turbulent Incompressible flows  Industrial Applications.Int. J. on Finite Volume, Electronical edition: http://averoes.math.univparis13.fr/htmlISSN 163406552004
 34 articleStarPU: a unified platform for task scheduling on heterogeneous multicore architectures.Concurrency and Computation: Practice and Experience2322011, 187198
 35 articleEvaluation of numerical wall functions on the axisymmetric impinging jet using OpenFOAM.Int. J. Heat Fluid Fl.672017, 2742
 36 articleA twophase mixture theory for the deflagrationtodetonation transition (DDT) in reactive granular materials.International journal of multiphase flow1261986, 861889
 37 articleDetailed Comparative Analysis of Interaction of a Supersonic Flow with a Transverse Gas Jet at High Pressure Ratios.Technical Physics / Zhurnal Tekhnicheskoi Fiziki6410October 2019, 14301440
 38 articleNumerical simulations of flow and heat transfer in a wallbounded pin matrix.Flow, Turbulence and Combustion10412020, 1944
 39 proceedingsS.S. BenhamadoucheR.R. HowardR.R. ManceauProc. 15th ERCOFTAC (SIG15)/IAHR Workshop on Refined Turbulence Modelling.EDF Chatou, France2011
 40 articleParsec: Exploiting heterogeneity to enhance scalability.Computing in Science & Engineering1562013, 3645
 41 articleAnisotropic Organised Eddy Simulation for the prediction of nonequilibrium turbulent flows around bodies.J. Fluid Struct.2482008, 12401251
 42 articleInfluence of the turbulence model for channel flows with strong transverse temperature gradients.International Journal of Heat and Fluid Flow70April 2018, 79103
 43 articleA compressible multifluid system with new physical relaxation terms.Annales Scientifiques de l'École Normale Supérieure5222019, 255295
 44 articleA low Mach correction able to deal with low Mach acoustics.Journal of Computational Physics378February 2019, 723759
 45 articleA new partially integrated transport model for subgridscale stresses and dissipation rate for turbulent developing flows.Phys. Fluids170651062005, 119
 46 articleClosure laws for a twofluid twopressure model.Comptes Rendus Mathematique334102002, 927932
 47 articleRecent improvements in the Zonal Detached Eddy Simulation (ZDES) formulation.Theor. Comput. Fluid Dyn.2662012, 523550
 48 articleAll speed scheme for the low Mach number limit of the isentropic Euler equations.Communications in Computational Physics1012011, 131
 49 articleAn elliptic blending differential flux model for natural, mixed and forced convection.International Journal of Heat and Fluid Flow632017, 15
 50 bookTheory of multicomponent fluids.135Springer Science & Business Media2006
 51 phdthesisDevelopment of a hybrid RANSLES model for the prediction of unsteady loads at the wall.Université de Pau et des Pays de l'AdourNovember 2020
 52 articleOmpss: a proposal for programming heterogeneous multicore architectures.Parallel processing letters21022011, 173193
 53 articleA taskdriven implementation of a simple numerical solver for hyperbolic conservation laws.ESAIM: Proceedings and Surveys63https://arxiv.org/abs/1701.05431January 2017, 228247
 54 articleRungeKutta discontinuous Galerkin method for the approximation of Baer and Nunziato type multiphase models.Journal of Computational Physics231112012, 40964141
 55 articleProperties of the hybrid RANS/LES filter.Theor. Comput. Fluid Dyn.1742004, 225231
 56 articleFlow interference between circular cylinders in tandem arrangement near to a plane wall.Mecánica Computacional3726November 2019, 10651074
 57 articleOn the behavior of upwind schemes in the low Mach number limit. IV: P0 approximation on triangular and tetrahedral cells.Computers & fluids38102009, 19691972
 58 articleOn the behaviour of upwind schemes in the low Mach number limit.Computers & fluids2811999, 6386
 59 articleSimulation of blast waves using OpenFOAM.Mecánica Computacional3726November 2019, 10751084
 60 articleNews on BaerNunziatotype model at pressure equilibrium.Continuum Mechanics and Thermodynamics3332021, 767788
 61 articleExtending the bounds of 'steady' RANS closures: Toward an instabilitysensitive Reynolds stress model.Int. J. Heat Fluid Fl.512015, 175194
 62 inproceedingsA buoyancy extension for eddyviscosity models for the natural convection regime.17th European Turbulence Conference (ETC2019)Torino, ItalySeptember 2019
 63 inproceedingsSensitization of eddyviscosity models to buoyancy effects for predicting natural convection flows.HEFAT 2019  14th International Conference on Heat Transfer, Fluid Mechanics and ThermodynamicsProc. HEFAT 2019  14th International Conference on Heat Transfer, Fluid Mechanics and ThermodynamicsWicklow, IrelandJuly 2019
 64 phdthesisTurbulence modelling of mixed and natural convection regimes in the context of the underhoodspace of automobiles.Université de Pau et des Pays de l'AdourDecember 2020
 65 articleSpECTRE: A taskbased discontinuous Galerkin code for relativistic astrophysics.Journal of Computational Physics3352017, 84114
 66 inproceedingsContrarotating jets: wake/mixing layer interaction.Proc. 10th ERCOFTAC (SIG15)/IAHR/QNETCFD Workshop on Refined Turbulence ModellingLaboratoire d'études aérodynamiques, UMR CNRS 6609, Université de Poitiers, France2002
 67 articleElliptic Blending Model: A New NearWall ReynoldsStress Turbulence Closure.Phys. Fluids1422002, 744754URL: hal02990466
 68 inproceedingsModélisation des transferts thermiques turbulents (conférence plénière).26e congrès français de thermiquePau, FranceMay 2018
 69 inproceedingsModelling of turbulent natural convection (keynote lecture).16th ERCOFTAC SIG15 Workshop on Modelling of wall bounded turbulent natural convectionJozef Stefan Institute (IJS)Ljubljana, SloveniaOctober 2019
 70 inproceedingsProgress in Hybrid Temporal LES (invited keynote paper).Papers contributed to the 6th Symp. Hybrid RANSLES Methods, 2628 September 2016, Strasbourg, France137Notes on Numerical Fluid Mechanics and Multidisciplinary DesignSpringer2018, 925URL: hal01391899
 71 articleRecent progress in the development of the Elliptic Blending Reynoldsstress model.Int. J. Heat Fluid Fl.512015, 195220URL: hal01092931
 72 unpublishedTurbulence modelling for CFD.November 2020, LecturePau, France
 73 inproceedingsTurbulent jet impinging onto a rotating disk: analysis of the RANS results.Proc. 13th ERCOFTAC (SIG15)/IAHR Workshop on Refined Turbulence ModellingTU Graz, Austria2008, URL: hal00385357
 74 articleExtension to various thermal boundary conditions of the elliptic blending model for the turbulent heat flux and the temperature variance.Journal of Fluid Mechanics905A1December 2020, 134
 75 inproceedingsPerformance of Various Turbulence Models for Simulating Subcritical HighReynolds Number Flows over a Smooth Cylinder.AIAA aviation 2021 forum2021, 2762
 76 articleA combined momentuminterpolation and advection upstream splitting pressurecorrection algorithm for simulation of convective and acoustic transport at all levels of Mach number.Journal of Computational Physics384May 2019, 1641
 77 articlePressurevelocity coupling allowing acoustic calculation in low Mach number flow.Journal of Computational Physics231162012, 55225541
 78 articleVMS and OESbased hybrid simulations of bluff body flows.Notes on Numerical Fluid Mechanics and Multidisciplinary Design1332016, 293308
 79 bookletParametric study of the effect of gyration on the flow and heat transfer of multiperforated plates.SOPRANO : Soot processes and radiation in aeronautical innovative combustors. H2020 european project (D3.1)2021
 80 articleA lowMach number fix for Roe’s approximate Riemann solver.Journal of Computational Physics230132011, 52635287
 81 articleModelizacion numerica de cargas de viento sobre un tanque de almacenamiento de combustible.Mecánica Computacional3727November 2019, 11631175
 82 articleA multiphase Godunov method for compressible multifluid and multiphase flows.Journal of Computational Physics15021999, 425467
 83 articleDiffuseinterface capturing methods for compressible twophase flows.Annual Review of Fluid Mechanics502018, 105130
 84 articleThermal large eddy simulation in a very simplified geometry of a solar receiver.Heat Transf. Eng.3362012, 505524
 85 articleA low Reynolds number dissipation rate equation model using the dissipation rate tensor equation and ellipticblending equation.J. Mech. Sci. Technol.2552011, 13611371
 86 inproceedingsRANS modelling for temperature variance in conjugate heat transfer.Proc. 5 th World Congress on Mech., Chem., and Material Eng. (MCM'19), Lisbon, Portugal2019