Author:
WU CHUI-JIE,WANG LIANG,WU JIE-ZHI
Abstract
An advanced moving-wall control strategy to manage the unsteady separated flow over a circular cylinder is developed. A two-dimensional numerical simulation of the flow over the cylinder at Re=500 based on diameter indicates that, when the downstream half of the cylinder surface is made flexible to form an appropriate travelling transverse wave, a ‘fluid roller bearing’ (FRB) is produced consisting of a row of vortices trapped by each wave trough, which can keep the global flow attached against a strong adverse pressure gradient, eliminating the vortex shedding and reducing the average drag by 85%. Physically, the FRB serves as a sheath to effectively inhibit the momentum–energy exchange between the thin fluid layer adjacent to the wall and the main stream, so that the wall layer is scaled only to the local wavelength and frequency and is independent of the global scales. Therefore, the global adverse pressure gradient on the lee side of the cylinder no longer influences the near-wall flow, and the common root cause of flow separation is removed. The input power for actuating the flexible wall is found to be 94% of the power saving due to drag reduction.
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics
Cited by
89 articles.
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