基于多线程并行的动态自适应建表加速算法在气相爆轰模拟中的应用

在带详细化学反应机理的气相爆轰过程数值模拟中，化学反应源项的刚性和非线性会使计算花费大量时间。为了提高化学反应的计算效率同时不降低计算精度，针对包含氢气与氧气详细化学反应机理的二维气相爆轰过程，提出了各线程独自建表和所有线程共有单表两种基于多线程并行的动态自适应建表（ISAT）算法，以取代原始的直接积分（DI），在不损失计算精度的条件下提高计算效率。两种并行算法分别采用了各线程独立建表和所有线程共建单表的方式，以此分析建表方式对计算效率的影响。在此基础上，还分析了建表容差判据和数值格式对计算效率的影响。研究结果表明：基于ISAT的并行算法在所有条件下均能提供与DI结果相当的计算精度，各线程独立建表的计算效率较共建单表的方法有更高的计算效率，其化学反应计算的加速比为2.17~2.43；并行建表算法不仅能够准确地描述二维气相爆轰波的传播过程，还可以提高化学反应流并行计算的计算效率。

Application of MPI-based ISAT Accelerated Algorithm in Gaseous Detonation Numerical Simulation

In the numerical simulation of gaseous detonation process with the detailed chemical reaction mechanism,the computation of chemical source term takes a large amount of CPU times due to the stiffness and nonlinearity of the term.To improve the computational efficiency without the loss of the computational accuracy for chemistry computation,two algorithms of in situ adaptive tabulation (ISAT) based on multi-threaded parallel integration (MPI) are proposed to replace the original direct integration (DI)method,and then applied in the computation of two-dimensional gaseous detonation process for H2/O2 medium with detailed chemical mechanism.In the parallel algorithms,two types of tabulation,namely the local tabulation for each processor and the global tabulation for all processors,are proposed,and the effect of the tabulation mode on the computational efficiency is investigated.Further,the influences of error criterions and numerical schemes on the computational efficiency of the algorithms are also examined.The results show that both the proposed algorithms can provide satisfactory computational accuracy compared with the results of DI,and the computational efficiency of the local tabulation for each processor with the chemical speedup ratio of 2.17 ～2.43 is higher than that of the global tabulation for all processors.The proposed parallel accelerated algorithms can not only accurately describe the propagation process of two-dimensional gaseous detonation wave,but also improve the parallel computational efficiency of of chemically reactive flows.