Wall Pressure Events from the Direct Numerical Simulation of a Turbulent Wall-Bounded Flow.

摘要

Wall pressure events beneath a turbulent wall-bounded flow are related to turbulence-generating events in the flow. The data base for a direct numerical simulation of channel flow allows the analysis of significant pressure events in space and time. Both positive and negative wall pressure events in the data base were detected with a pressure peak conditional sampling technique. The recovered events were ensemble averaged to provide a space and time record of a typical event. Both positive and negative pressure peak events have regions of pressure of the opposite sign just ahead of and just behind them, but the regions of opposite sign do not extend to the sides of the events. Although a positive pressure peak event begins as a double positive pressure hump, the downstream hump eventually dominates and becomes the pressure peak before the event decays. Negative pressure peak events begin as a positive hump leading a negative hump. The negative hump grows to become the peak before decaying. Both positive and negative events begin about 400 wall units upstream of where the maximum pressure occurs and persist to about 400 wall units downstream of the pressure peak. The entire event lasts about 0.4 delta/U Tau. Direct numerical simulation, Pressure peak, Turbulent boundary layer, Wall pressure.