平板边界层壁面局部脉冲激发大涡结构起因的数值模拟

Numerical simulation of inducing large eddies in boundary layer through local impulse at the wall

构建了边界层壁面局部脉冲扰动诱导大涡结构的初始理论模型,采用直接数值模拟的方法,研究了边界层壁面局部脉冲激发大涡结构起因的问题。计算结果表明:局部脉冲激发大涡结构成因的许多特点,如幅值演化、雷诺切应力功率、高低速条纹结构、流向涡的产生、上喷和下扫过程、平均速度剖面存在的拐点和严重扭曲以及类似于发卡涡的特征等现象与实验结果和某些数值结果非常相似;另外,壁面局部脉冲的强度、影响区域、加载时间、分布方式对边界层流中大涡结构起因的特性起着决定性的作用,壁面脉冲也是边界层流中激发大涡结构的重要途径之一。

Local impulse disturbance at the wall was designed as an initial theoritical model to induce large eddies in boundary layer, and cause of the large eddies was studied through numerical simulation. Results show that amplitudes evolution, Reynolds stress power, high and low speed stripe, formation of streamwise vortices, ejection and sweep, inflexions and distortion at the mean velocity profiles, as well as hairpinlike vortices are consistent with experimental and other stimulant conclusions. In addition, many factors to induce large eddies are of importance; such as impulse strength, influencing area, loading time and distributing type etc. Local impulse at the wall is a crucial approach to excite large eddies in boundary layer.