Behavior of Separated and Reattaching Flow Formed over a Backward Facing Step

抄録

Wind tunnel measurements were done for the separated and reattaching flow formed over a backward-facing step. Turbulent energy and turbulent normal stress balances were estimated from the measured data of mean velocities, Reynolds stresses, and turbulent triple products. The main objective of the experiments is to analyze the turbulent structure inside the reattaching shear layer, including the reverse flow, in detail. The results indicated different turbulent structures in three classified regions of the backward-facing step flow, first the dead air region, second the near wall region just upstream and downstream of the reattachment, and third the separated shear layer region. The second region is the one in which the transverse diffusion by turbulence in the turbulent energy balance equation plays an important role in comparison with other regions. In the reverse flow region just upstream of the reattachment included in the second region, the production term by shear stress, the transverse diffusion term by turbulence, and the advection term similarly help to balance the dissipation term.