Numerical identification of flow‐induced oscillation modes in rectangular cavities using large eddy simulation

Self-sustained oscillations are present in a wide variety of flows. For flows passing cavities, acoustics can play a role in the physical mechanisms triggering and maintaining the oscillation phenomena. This is the case for the flow over rectangular cavities, which is studied in this paper. The compressible LES Navier-Stokes equations are solved for cavities with an upstream laminar boundary layer. The flow passing rectangular cavities is computed, varying two different parameters related to the physics of the problem, Mach number and length of the cavity divided by the momentum thickness of the boundary layer at the leading edge. This paper intends to prove that the switch between shear-layer oscillation mode, characterized by an acoustic feedback process, and wake oscillation mode, characterized by a large-scale vortex shedding with Strouhal number independent of Mach number, can be identified using large eddy simulation, and consequently, with much less computational effort than in other studies in literature, where direct numerical simulation has been applied.

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