Direct numerical simulation of turbulent mixing layers with periodic forcing induced inflow

The direct numerical simulation of the turbulent mixing layer with periodically-forced inflow is performed. The angular frequency ωc was set as a control parameter. To compare the experimental study of Naka et al. (2010), the angular frequency is set to be ω = 0.83 (Case A) and 3.85 (Case B). In the present simulation, the momentum thickness shows the Case A achieved the mixing enhancement, while Case B achieves its suppression. Due to the both controls, the Reynolds normal shear stress, especially vv increases behind the periodic forcing. The Reynolds shear stress uv is suppressed in the Case B at downstream. This region is agree with that the mixing suppression is found in the momentum thickness. Furthermore, the anisotropic tensor indicates that two dimensional large coherent structure is generated in the Case B in which mixing was suppressed.