Characteristics of stretched vortical structures in two-dimensional stagnation flow

Quantitative aspects on the relationship of the incoming freestream turbulence and the stretched vortical structures developed in a two-dimensional stagnation region are reported in this work. The optimal time delay that resulted from the cross correlation of the velocity fluctuations measured in the stagnation region and the wall-pressure fluctuations is successfully normalized by the freestream velocity and the width of the bluff body, implying that this time delay is attributed to the effect of mean-flow convection. The statistics regarding the unsteady stretched vortical structures detected at a fixed location in the stagnation region, in terms of the number of events per unit time and the averaged time duration of the flow structures detected, are successfully scaled by L_x and w_o, where L_x and w_o are the integral length scale and the intensity of grid-generated turbulence, respectively.