We present a Lax-Wendroff discontinuous Galerkin (LWDG) method combining with adaptive mesh refinement (AMR) to solve three-dimensional hyperbolic conservation laws. Compared with Runge-Kutta discontinuous finite element method (RKDG) the method has higher efficiency. We give an effective adaptive strategie. Equidistribution strategy is easily implemented on nonconforming tetrahedral mesh. Error indicator is introduced to solve three-dimensional Euler equations. Numerical experiments demonstrate that the method has satisfied numerical efficiency.

A numerical method is developed for two-dimensional nonequilibrium radiation diffusion equations.Discontinuous Galerkin method is applied in spatial diseretization in which numerical flux is constructed with weighted flux averages.Implicit-explicit integration factor method for time discretization is applied to nonlinear ordinary differential equations which is obtained with discontinuous Galerkin method. Radiation diffusion equations with multiple materials are solved on unstructured grids in numerical tests.It demonstrates that the method is effective for high nonlinear and tightly coupled radiation diffusion equations.

We discuss numerical simulation of one-dimensional non-equilibrium radiation diffusion equations.A weighted numerical flux between adjacent grid cells is obtained by solving heat conduction equation with discontinuous coefficient.With this numerical flux of diffusive generalized Riemann problem(dGRP),a discontinuous finite element method is proposed for radiation diffusion equations. A backward Euler time diseretization is applied for semi-discrete form and a Picard iteration is used to solve nonlinear system of equations.Numerical results demonstrate that the method has a capability of capturing strong gradients and can be accommodated to discontinuous diffusion coefficient.

Domain decomposition parallel algorithms for one-and two-dimensional diffusion equations are studied by using multi-step evaluation revisions for interface points with fractional temporal index.Stability conditions are loose.In the algorithm,schemes with fractional step and large spacing discretization are used to evaluate interface points.The algorithms have same accuracy as full implicit method,while their stability bounds are released by q,the number of fractional step evaluations on interfaces between two neighboring temporal steps,times compared with existing algorithms.Convergence is proven rigorously with discrete maximum principle.Numerical experiments on parallel computers confirnl theoretical conclusions.They demonstrate looser stability conditions,good accuracy and parallel expansibility of the algorithms.

An explicit method is proposed to initiate three-layer difference scheme for two-dimensional heat problems.Stability and convergence theorem is shown with a three-layer domain decomposition parallel difference algorithm with inner boundary prediction-correction and explicit initialization.Parallel numerical experiments show that the method is numerical stable,and is more convenient in program realization compared with usual implicit initialization method.It reduces numerical errors greatly compared with existing perturbation methods.