Velocity field and parametric analysis of a subsonic, medium-Reynolds number cavity flow

Abstract

Cavity flows are a class of flows bounded by material structures, where a recirculation region is present, and they are found in many practical applications. In the present study, the interaction between a boundary layer and an open parallelepipedic cavity develops a Kelvin-Helmholtz-like instability coupled with the cavity recirculation. PIV measurements of the flow are carried out in two orthogonal planes inside the cavity, for different aspect ratios, incompressible flow conditions, and Reynolds numbers in the range 1,900-12,000. Mean velocity and secondorder moments of velocity fluctuations reveal the flow morphology. For particular conditions, centrifugal instabilities appear that are induced by flow curvature due to wall confinement. The use of an identification criterion indicates the presence of pairs of counter-rotating vortices winded around the recirculation. A parametric analysis is conducted, and the inviscid Rayleigh discriminant provides the potentially unstable flow regions inside the cavity. Finally, a stability parameter considering the ratio between centrifugal destabilizing effects and stabilizing viscous effects is carried out and gives thresholds for the emergence of the centrifugal instability. The study draws to an end with a comparison with a well-documented lid-driven cavity flow.

Flow regimes in a trapped vortex cell

“…This is in contrast to the complex internal flow topology observed in rectangular open cavity flows, e.g. Faure et al (2006); Faure (2014), where secondary separation is a relevant feature, and affects remarkably the shear layer dynamics, Kuo and Huang (2001). Rigorous results, Bunyakin et al (1998), show that a region of the wall with adverse pressure gradient has to exist in a vortex cell.…”

Parametrical study and turbulence analysis of high-speed flows around an open cavity using large eddy simulation

“…It was observed that two primary mechanisms with distinctly different characteristic frequencies would influence the vorticity flux and generation as well as the pressure variations around the trailing edge corner. Recently, Faure et al (Faure 2014) investigated the flow morphology inside the cavity for various aspect ratios, impressible flow conditions and Reynolds numbers with the mean velocity and second-order moments of velocity fluctuations.…”