激波诱导火焰界面失稳的并行化学加速计算

Parallel Chemistry Acceleration Computations of Flame Interface Instability Induced by Shock Wave

在带有详细化学反应机理的可压缩反应流数值模拟中,化学反应源项的计算会极大增加计算时间,基于建表技术的化学加速算法可以通过查找数据表中的数据来替代化学反应计算,从而有效提高计算效率,但数据表尺寸的过度增长会导致计算的中断.文章提出了基于两种数据表容量控制策略的并行动态存储/删除算法,并在激波诱导火焰界面失稳的数值模拟中进行了应用,以考察算法的性能.两种数据表容量控制策略分别为单表容量(M sin)控制和总表容量(M tot)控制,当单个数据表尺寸达到M sin或总数据表尺寸达到M tot时,对数据表进行节点删除,以保证计算的正常进行.计算结果表明,文章提出的基于表容量控制的并行加速算法,其计算准确度和计算效率之间存在关联,具有较好计算准确度算例显示了较高的计算效率.在不同的M sin和M tot条件下,计算的化学加速比在2.73~3.93之间.两种表控策略的组合影响了数据表删除的频率和删除之间的同步性,当数据表删除频率小、删除同步性强时,化学加速比要更高.

In the numerical simulations of compressible reacting flow with detailed reaction mechanism,the computations of chemical source term can spend huge CPU time.A chemistry acceleration algorithm based on tabulation technique can greatly improve the computational efficiency,through replacing the direct computation of chemical reaction by searching the data in a table.However,excessive growth of the table size can give rise to a breakoff of the computations.This study presented the parallel dynamic storage/deletion algorithm based on two table size control strategies.To test the computational performance of the algorithm,the simulations of flame interface instability induced by a shock wave have been carried out.Both table size control strategies in the algorithm include the single table size(M sin)control and the total table size(M tot)control.Once the size of single table reached M sin or the total size of the tables reached M tot,a nodal deletion was performed for all the tables in order to maintain the table size.The results show that there exists relationship between computational accuracy and efficiency for the algorithm based on the table size control.The better computational efficiency corresponds to the higher computational accuracy.The chemical speedup ratio resulted from simulations ranges in 2.73~3.93 when M sin and M tot vary.The combination of both table size control strategies plays an important role in affecting the deletion frequency of tables and the synchronization among the table deletion events.The chemical speedup ratio is larger when smaller deletion frequency of tables and better synchronization occur.