A Conservative Enforcing Positivity-preserving Algorithm for Diffusion Scheme on General Meshes

For a class of diffusion schemes not satisfying the property of positivity-preserving, we propose an enforcing positivity algorithm. It is locally conservative and easy to be implemented in existing codes. Moreover, this algorithm can be performed on both structured and unstructured meshes. Numerical experiments demonstrate that in terms of L2 error and conservation this algorithm is much better than the trick of directly enforcing the negative values to zero (ENZ), which has been used in applications, meanwhile, in terms of L∞ error it is approximate to ENZ and CEPA repairing algorithms.