HIGHLY ANISOTROPIC NONLINEAR TEMPERATURE BALANCE EQUATION AND ITS NUMERICAL SOLUTION USING ASYMPTOTIC-PRESERVING SCHEMES OF SECOND ORDER IN TIME

This paper deals with the numerical study of a nonlinear, strongly anisotropic heat equation. The use of standard schemes in this situation leads to poor results, due to the high anisotropy. An Asymptotic-Preserving method is introduced in this paper, which is second-order accurate in both, temporal and,spacial variables. The discretization in time is done using an L-stable Runge-Kutta scheme. The convergence of the method is shown to be independent of the anisotropy parameter 0 < epsilon < 1, and this for fixed coarse Cartesian grids and for variable anisotropy directions. The context of this work are magnetically confined fusion plasmas.