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High-order relaxation schemes for nonlinear degenerate diffusion problems. (English) Zbl 1171.65065
This paper deals with diffusive relaxation schemes for the numerical approximation of nonlinear parabolic equations. The main idea is to approximate the original partial differential equation (PDE) with a suitable semilinear hyperbolic system with stiff relaxation terms. As the relaxation parameter is convergent to zero, the solution of the hyperbolic system converges to the solution of the original PDE. An analysis of relaxation schemes, from both the theoretical and computational point of view, is made for the nonlinear degenerate diffusion problem
${\partial u \over \partial t} = D\Delta(p(u)), ~x \in {\mathbb R}^d, ~t>0,$ with initial data in $$L^1(\mathbb R^d)$$. The function $$p:{\mathbb R} \rightarrow {\mathbb R}$$ is nondecreasing and Lipschitz continuous. The diffusion problem is degenerate if $$p(0)=0$$. Error estimates and a convergence analysis are developed for semidiscrete schemes with a numerical analysis for fully discrete relaxed schemes. 1D and 2D numerical results show the high accuracy of the proposed numerical schemes, also in the degenerate case. The authors assert that these numerical schemes can be easily implemented on parallel computers. Numerical results are given for linear diffusion and for porous media equation.

##### MSC:
 65M20 Method of lines for initial value and initial-boundary value problems involving PDEs 65M12 Stability and convergence of numerical methods for initial value and initial-boundary value problems involving PDEs 35K65 Degenerate parabolic equations 65M15 Error bounds for initial value and initial-boundary value problems involving PDEs 65Y05 Parallel numerical computation
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