EPTT 2020

12th Spring School on Transition and Turbulence

Dynamic flow structures in the wake of a surface-mounted finite-height square prism

Submission Author: Bárbara Louize da Silva , SC
Co-Authors: Bárbara Louize da Silva, David Sumner, Donald Bergstrom
Presenter: Bárbara Louize da Silva

doi://10.26678/ABCM.EPTT2020.EPT20-0038

 

Abstract

The flow around surface-mounted finite-height square prisms is complex due to the strong three-dimensionality of the flow, especially for prisms of small aspect ratio AR = H/D (where D is the prism width and H is its height). Different flow models have been proposed in the literature to describe the dynamic flow structures in the wake of surface-mounted prisms, although gaps and inconsistencies remain – for instance, in explaining the origins of regions of high streamwise vorticity in the upper part of the wake. This study aims to explore the dynamic flow structures in the wake of a surface-mounted finite-height square prism of AR = 3 at a Reynolds number of Re = 500 based on the prism width, with a thin boundary layer on the ground plane. Large-eddy simulation results were analyzed using a phase-average approach to extract the dominant periodic features of the wake. The phase-averaged flow fields show the occurrence of alternating structures similar to half-loops, although the regions of highest streamwise vorticity take place outside the near-wake formation region and are associated with the downwash and with a large-scale motion of the wake in the transverse direction. The dynamic behavior of the wake reveals the alternate entrainment of fluid close to the ground plane. In contrast, the upper region of the wake is more symmetric.

Keywords

surface-mounted finite-height square prism, turbulent wake, bluff body, Large Eddy Simulation, phase average

 

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