SUMMARYNonequilibrium radiation diffusion problems are described by the coupled radiation diffusion and material conduction equations. Because of the highly nonlinear, strong discontinuous, and tightly coupled phenomena, solving this kind of problems is a challenge. We construct two finite volume element schemes for the equations. One of them is monotone on many kinds of meshes, which is proved theoretically and verified by numerical tests. The other one is hard to satisfy the monotonicity, but this defect can be corrected by different repair techniques. Numerical results show that these new methods are practical and efficient on distorted meshes.Copyright © 2013 John Wiley & Sons, Ltd.

Two-dimensional three-temperature (2-D 3-T) radiation diffusion equations are widely used to approximately describe the evolution of radiation energy within a multi-material system and explain the exchange of energy among electrons, ions and photons. Their highly nonlinear, strong discontinuous and tightly coupled phenomena always make the numerical solution of such equations extremely challenging. In this paper, we construct two finite volume element schemes both satisfying the discrete conservation property. One of them can well preserve the positivity of analytical solutions, while the other one does not satisfy this property. To fix this defect, two as repair techniques are designed. In addition, as the numerical simulation of 2-D 3-T equations is very time consuming, we also devise a mesh adaptation algorithm to reduce the cost. Numerical results show that these new methods are practical and efficient in solving this kind of problems.

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