简单隅角平衡输运格式在辐射流体力学计算中的应用
Simple Corner Balance Method for Transport in Radiation Hydrodynamics Calculations
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摘要: 将简单隅角平衡(SCB)格式应用于惯性约束聚变(ICF)辐射流体力学数值模拟, 实现对辐射输运方程的离散求解, 重点讨论辐射输运与物质能量方程组在空间上的两种耦合实现形式: 子网格-网格(subcell-cell)的松耦合方式和全子网格(subcell-subcell)的紧耦合方式。数值结果表明: subcell-cell松耦合方式的数值结果严重依赖于网格的光学厚度, 仅适用于光性薄网格的辐射传输计算, 而采用subcell-subcell的紧耦合方式, 网格剖分不受辐射自由程的限制, 只需分辨物理量的梯度变化, 能同时兼顾光性薄和光性厚网格辐射传输计算。Abstract: Simple Corner Balance (SCB) spatial discretization is feasible for solving transport equations on quadrilateral grids. We generalize it for nonlinear radiative transfer equations in the system of radiative hydrodynamics. As four radiation unknowns are defined in four subcells of a cell, how to discretize electronic temperature while radiation and mather are strong coupled via absorption and emission. In this paper, subcell-cell lax coupling way and subcell-subcell tight coupling way are considered. Numerical tests demonstrate in subcell-subcell tight coupling way meshes are only required sufficiently fine to resolve the transport processes on the coarser length-scale associated with the diffusion of radiation energy through opaque media, other than required to resolve down to a photon mean free path in subcell-cell lax coupling way.