逆压梯度下近壁湍流的喷射和扫掠

The Ejection and Sweep in the Wall Region of a Turbulent Boundary Layer Under Adverse Pressure Gradient

采用Fourier谱展开和紧致有限差分格式 ,选用两组共振三波为相干结构的初值 ,计算了其在零压和逆压梯度作用下的演化。对演化后期流场的 2 ,4象限的运动进行了详细的分析。结果发现 ,在逆压梯度下 ,扫掠对雷诺应力的贡献要强于喷射。无论是在零压梯度还是逆压梯度下 ,uv和u2 在法向的输运主要是靠Q2 和Q4这两种运动来完成的。零压梯度下喷射部分对输运的贡献大于扫掠的部分。而在逆压梯度下喷射部分对输运的贡献明显减少 。

The evolution of coherent structures in the wall region of a turbulent boundary layer under adverse pressure gradients was studied by using DNS method.The motio ns of the second and the fourth quadrant were analyzed.The results show that to the shear stress,the contribution of sweep motions is stronger than that of ejec tions under adverse pressure gradient.And the sweeps contribute to the transport of shear\|stress and kinetic energy of turbulence more strongly than the ejecti ons under adverse pressure gradient.