21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-3.10.2

BEHAVIOURS OF SEPARATED AND REATTACHING FLOW FORMED OVER BACKWARD FACING STEP

Rinoie K., Shirai Y., Saito Y., Sunada Y.
University of Tokyo, Japan

Keywords: separated, reattaching, flow, backward facing step

Wind tunnel measurements were done for the separated and reattaching flow formed over 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, i.e. the dead air, reverse flow and separated shear layer regions. In the reverse flow region, the transverse diffusion by turbulence in the turbulent energy balance equation is positive. The production term by shear stress, the transverse diffusion term by turbulence, and the advection term similarly help to balance the dissipation term in the same region. Classified Reynolds stress that are u positive and v negative contribute the most to the generation of Reynolds shear stress in this region.

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