For high efficiency simulation of three-dimensional spherical implosion and the difficulty of adding radiation source on traditional Cartesian orthogonal grid, a multi-block non-orthogonal mesh generation method is developed. An efficient parallel algorithm of three-dimensional diffusion scheme on these meshes is proposed. It was applied to the simulation of radiation hydrodynamic equations and the asymmetry study in three-dimensional implosion problems. Effectiveness of the algorithm is shown. Scalability is demonstrated with a parallel efficiency above 69% on 5400 processors.

Targeting at SN algorithm for the neutron transport equation in the two-dimensional spherical coordinate system, we propose a directed graph model based on a (cell, direction) two-tuple, and design a multi-level parallel SN algorithm with controllable granularity on the basis of the existing parallel pipeline algorithm based on directed graph. Among them, a combination of domain decomposition and parallel pipeline is used to mine parallelism in the space-angle direction, and an energy group pipeline parallel method is proposed. Furthermore, by setting appropriate pipeline granularity, the overhead of scheduling, communication and idle waiting are well balanced. Experimental results show that the algorithm can effectively solve the neutron transport equation in the two-dimensional spherical coordinate system. For a typical neutron transport problem with 960 000 grids, 60 directions, 24 energy groups, and billions of degrees of freedom, the parallel program achieved 71% parallel efficiency on 1920 cores of a domestic parallel machine.