Stabilized bi-cubic Hermite Bézier finite element method with application to Gas-plasma interactions occurring during massive material injection in Tokamaks

Ashish Bhole (1, 2) , Boniface Nkonga (1, 2) , José Costa (1) , Guido Huijsmans (3, 4) , Stanislas Pamela (5) , Matthias Hoelzl (6)

1 LJAD - Laboratoire Jean Alexandre Dieudonné
2 CASTOR - Control, Analysis and Simulations for TOkamak Research
3 IRFM - Institut de Recherche sur la Fusion par confinement Magnétique
4 TU/e - Eindhoven University of Technology [Eindhoven]
5 CCFE - Culham Centre for Fusion Energy
6 IPP - Max-Planck-Institut für Plasmaphysik [Garching]

Development of a numerical tool based upon the high-order, high-resolution Galerkin finite element method (FEM) often encounters two challenges: First, the Galerkin FEMs give central approximations to the differential operators and their use in the simulation of the convection dominated flows may lead to the dispersion errors yielding entirely wrong numerical solutions. Secondly, high-order, high-resolution numerical methods are known to produce high wave-number oscillations in the vicinity of shocks/discontinuities in the numerical solution adversely affecting the stability of the method. We present the stabilized finite element method for plasma fluid models to address the two challenges. The numerical stabilization is based on two strategies:Variational Multiscale (VMS) and the shock-capturing approach. The former strategy takes into account (the approximation of) the effect of the unresolved scales onto resolved scales to introduce upwinding in the Galerkin FEM. The latter adaptively adds the artificial viscosity only in the vicinity of shocks. These numerical stabilization strategies are applied to stabilize the bi-cubic Hermite B´ezier FEM in the computational framework of the nonlinear magnetohydrodynamics (MHD) code JOREK. The application of the stabilized FEM to the challenging simulation of Shattered Pellet Injection (SPI) in JET-like plasma is presented. It is shown that the developed numerical stabilization model improves the stability of the underlying numerical algorithm and the computational cost required to reveal the complex physics is reduced. The physical and numerical models presented can be used to perform expensive simulations of the plasma applications in large computational domains such as JET, and ITER.

Mots clés: Stabilized FEM; Variational Multi-scale methods; Shock-capturing stabilization; bi-cubic Hermite Bézier FEM; Magnetohydrodynamics; Full MHD model; Massive material injection in tokamak plasma; Shattered pellet injection

Domaines: Modélisation et simulation; Analyse numérique [math.NA]; Physique des plasmas [physics.plasm-ph]

Ashish Bhole, Boniface Nkonga, José Costa, Guido Huijsmans, Stanislas Pamela, et al.. Stabilized bi-cubic Hermite Bézier finite element method with application to Gas-plasma interactions occurring during massive material injection in Tokamaks. Computers & Mathematics with Applications, 2023, 142, pp.225-256. ⟨10.1016/j.camwa.2023.04.034⟩. ⟨hal-03811224⟩