抄録
In low Reynolds numbers region, a laminar separation and laminar separation bubble was observed on upper surface of airfoil. This flow field could be realized over a backward-facing step. The numerical calculation over a backward-facing step was carried out to examine both separation and reattachment of shear layer at Reynolds number of 2,000 based on the step height. The flow after the separation reattached of being instability of separated share layer by amplifying the disturbance. In reattachment region, the time change of reattachment position indicated that the dominant spectrum was the high and frequency components. The reattachment position was locally increased by this high frequency component. As a result, we confirmed that the reattachment position of span-wise direction was three-dimensional.
