Abstract

We study the numerical approximation of a multigroup three temperature plasma model. A reformulation of the model is proposed in order to derive robust convex combination-based schemes. The produced schemes are naturally well-suited to handle stiff source terms and can be analyzed. However, because of the very large size of the resulting linear system, a direct numerical solving cannot be performed in practice if a large number of cells or frequency groups is used. Consequently, a decoupling procedure is presented in order to greatly reduce the numerical cost of the method while keeping the fundamental discrete properties. After detailing the schemes derivation followed by the practical numerical resolution and the decoupling procedure, a numerical analysis is performed, and strong stability properties are proven. Several numerical test cases are carried out to demonstrate the interest of the numerical approach.

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