Abstract
The streamwise and spanwise velocity components in the wall region of a turbulent channel flow have been studied in order to help clarify the three-dimensional nature of the bursting process. The bursts were detected at y+ ≈ 15 by using short time (VITA.) aver ages of the streamwise velocity component. Conditional averages with a time delay were obtained from wall elements having a spanwise spatial separation. The defect of streamwise momentum, directly before the detection of the burst, is formed by low-speed fluid coming in from the positive and negative spanwise direction. The strength of the defect region slowly increases and possibly forms a low-speed streak as observed in visualization studies. The extent of this motion in the spanwise direction has been studied using space-time correlation techniques.
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