汽车外流场DES/RANS模拟研究

DES and RANS of Vehicle External Flow Field

汽车外流场具有非定常、大分离和涡结构复杂的特点.采用分离涡模拟(DES)方法对某汽车外流场进行了数值模拟分析,将压力分布、摩擦因数分布、尾部速度和湍动能分布等结果与雷诺平均模拟(RANS)方法进行了比较.计算结果表明:在时均结果上,DES和RANS结果差别不大,但DES方法在处理非定常流动和捕捉含能结构方面优势明显,更能真实地反应汽车外流场的复杂特征.DES方法计算量较大,RANS方法在获取流场的时均信息方面显得更加经济.

Unsteady, massive separation and complex vortex structures are the cle external flow field. The numerical simulation of the external flow field around typical features of vehi- a car was carried out by using DES methods. The results such as pressure distribution, skin friction coefficient distribution, veloci- ty and turbulence kinetic energy distribution in the wake were compared with the results by using the RANS methods. It has been indicated that it has few differences between RANS and DES in obtaining the time-average results, but DES methods are particularly suited and clearly superior to RANS methods for unsteady flows and in capturing the structures which contain energy. Hence, DES methods is more suit- able to calculating the complex flow field around a car. In contrast to RANS, computational cost is more expensive for DES, and RANS is economical for obtaining the time-average information of flow field.