CHINESE JOURNAL OF COMPUTATIONAL PHYSICS ›› 2020, Vol. 37 ›› Issue (4): 379-392.

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A Positivity-preserving Finite Volume Scheme Based on Second-order Scheme

ZHAO Fei1,2, SHENG Zhiqiang2, YUAN Guangwei2   

  1. 1. College of Science, North China Univevsity of Technology, Beijing 100144, China;
    2. Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
  • Received:2019-05-16 Revised:2019-08-06 Online:2020-07-25 Published:2020-07-25

Abstract: Based on a second-order accurate linear scheme, a normal flux is reconstructed to obtain a nonlinear finite volume scheme with a two-point flux discrete stencil on tetrahedral meshes. It is suitable for discontinuous and anisotropic diffusion coefficient problems, and can be generalized to general polyhedral meshes. It is unnecessary to assume that auxiliary unknowns are non-negative, and avoids artificial processing of "setting negative to be zero" in calculating auxiliary unknowns. Moreover, it is proved that the linearized scheme at each nonlinear iteration step satisfies strong positivity-preserving, i.e., as the source term and boundary condition are non-negative, non-zero solution of the scheme is strictly greater than zero. Numerical tests verify that the scheme has second-order accuracy and is strong positivity-preserving.

Key words: diffusion equations, tetrahedral meshes, finite volume scheme, strong positivity-preserving

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