惯性约束聚变中的辐射流体力学问题，涉及到多种介质和大的变形，并具有明显的三维特征，对它的高置信度数值模拟需要在三维非结构网格上进行。在多介质辐射流体力学模拟中，网格会随着流体的运动而发生大的变形，并导致在同一个网格内可能会出现多种物质，而且网格中的物质界面会随着时间动态变化，产生三维混合介质网格，因此如何在混合介质网格上求解三维辐射扩散方程，就是目前亟待解决的问题。本项目将重点研究和发展三维非结构混合介质网格上的扩散方程求解格式，给出辐射扩散方程的混合介质网格封闭模型；在此基础上，研究混合介质网格上辐射扩散方法与流体力学ALE方法的耦合。研究成果有望为惯性约束聚变中相关问题的物理分析和机理研究提供方法和程序支撑。

In the study of radiation hydrodynamics in ICF, multi-material with three dimensional large deformation needs to be treated. Numerical simulation with high fidelity needs to be performed on three dimensional unstructured grids.In the simulation of multi-material radiation hydrodynamics, the grids move with the fluid and become deformed, leading to multi-material existing in one cell, and the material interface in the cell changes with time. This kind of the cell is called the mixed cell. How to slove the radiation diffusion equation on three dimensional mixed cells is a new question needs to be resolved. In this project, we will place emphases on the development of methods and closure models for three dimensional mixed cells to solve the diffusion equation. Based on this, we will investigate the coupling method of multi-material radiation diffusion simulation and hydrodynamics ALE simulation. This project is expected to provide proper methods and codes for physical analysis and mechanism study in ICF.