DDES延迟函数在超声速底部流动中的性能分析

DDES是广泛应用的一类RANS/LES混合方法,其通过引入延迟函数保证近壁区的RANS模化,对分离流动十分有效。目前DDES已发展了多种不同的延迟函数,但对各延迟函数的性能特点认识尚不够充分,尤其缺乏超声速流动中的相关研究。围绕DDES方法中不同延迟函数开展研究工作,选取超声速底部流动作为测试算例,通过与实验数据的系统对比分析,考察不同延迟函数在超声速分离流动中的分布规律、作用效果及模型求解能力。研究表明,不同延迟函数作用范围与求解能力存在差异,其中DDES-F1能够在起到保护作用的同时不损害模型的求解精度,对该流动较为有效,所得结果与实验数据吻合较好。

Performance of delayed functions in DDES for supersonic base flow

The DDES is a widely used approach among RANS/LES hybrid methods.It introduces the delayed function to ensure full RANS mode in the near-wall region,and has been proven to be quite efficient for separated flows.Up to date,various different delayed functions have been developed.However,the understanding to the performance and characteristics of different delayed functions still remains not comprehensive,especially lacking investigation on supersonic flows.The research focuses on the different delayed functions in the DDES methods by employing the supersonic base flow as the validation case.Through systematic comparisons with the experimental data and detailed analyses,the distributions and shielding behavior of different delayed functions together with resolving capabilities of different models are investigated.Studies show that there exist discrepancies in the shielding behavior and resolving capabilities between different delayed functions.Besides,DDES-F1 behaves appropriately in this supersonic separated flow and reproduces the experimental data very well,providing sufficient protection without impairing the model's numerical accuracy.