Section: New Software and Platforms

Platforms

FluidBox

Participants : Boniface Nkonga [contact] , Hervé Guillard.

FluidBox is a software dedicated to the simulation of inert or reactive flows. It is also able to simulate multiphase, multi-material and MDH flows. There exist 2D and 3D dimensional versions. The 2D version is used to test new ideas that are later implemented in 3D. Two classes of schemes are available : a classical finite volume scheme and the more recent residual distribution schemes. Several low Mach number preconditioning are also implemented. The code has been parallelized with and without domain overlapping. The linear solver PaStiX is integrated in FluidBox. A partitioning tool exists in the package and uses Scotch.

Plato

Participants : Hervé Guillard [contact] , Boniface Nkonga, Giorgio Giorgiani, Afeintou Sangam, Elise Estibals.

PlaTo (A platform for Tokamak simulation) is a suite of data and softwares dedicated to the geometry and physics of Tokamaks. Plato offers interfaces for reading and handling distributed unstructured meshes, numerical templates for parallel discretizations, interfaces for distributed matrices and linear and non-linear equation solvers. Plato provides meshes and solutions corresponding to equilibrium solutions that can be used as initial data for more complex computations as well as tools for visualization using Visit or Paraview. The use of this platform for large scale simulation has been validated up to $𝒪\left(1000\right)$ CPU [14] [10]

The numerical schemes used in the platform are of finite element or finite volume type. To deal with the geometry of tokamaks, Plato uses curved prisms made of a tensor product of unstructured triangular meshes in the poloidal plane by 1D meshes in the toroidal direction. The numerical strategy uses 3D finite volume schemes for the first-order terms and P1 finite element for second-order terms. Several models (anisotropic diffusion, Grad-Shafranov equilibrium, reduced MHD model) have been validated and are presently available. In addition, a stabilized finite element method using a tensor product of $C^1$ (Powell-Sabin) triangular element by 1D cubic splines in the toroidal direction has been recently developed and is presently in a validation phase.

Jorek-Inria

Participants : Hervé Guillard, Boniface Nkonga, Emmanuel Franck [Tonus, Inria Nancy - Grand Est] , Ahmed Ratnani [IPP Garching] .

https://gforge.inria.fr/projects/jorek/

Jorek-Inria is a new version of the JOREK software, for MHD modeling of plasma dynamic in tokamaks geometries. The numerical approximation is derived in the context of finite elements where 3D basic functions are tensor products of 2D basis functions in the poloidal plane by 1D basis functions in the toroidal direction. More specifically, Jorek uses curved bicubic isoparametric elements in 2D and a spectral decomposition (sine, cosine) in the toroidal axis. Continuity of derivatives and mesh alignment to equilibrium surface fluxes are enforced. Resulting linear systems are solved by the PASTIX software developed at Inria-Bordeaux.

The new formulation of the Jorek-Inria code extends this approximation strategy by introducing more flexibility and a variety of finite elements used in the poloidal plane and in the toroidal direction. It also proposes a sparse matrix interface SPM (Sparse Matrix Manager) that allows to develop clean code without a hard dependency on any linear solver library (i.e. PetSc, Pastix, Mumps, ...). It is expected that the two developments PlaTo and Jorek-Inria will merge in the next years.