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Mechanical Engineering
Caltech
Abstract-
We present simulation and modeling efforts of flow/acoustic resonance in
subsonic flow over two-dimensional rectangular cavities. The goal is to educe
low-order models, needed for the design of effective feedback control laws, from
simulations of the Navier–Stokes equations. The results show two different
mechanisms for self-sustained oscillation depending on the flow parameters.
Results for the first mode, involving upstream acoustic scattering from the
vortex-edge interaction, are in good agreement with experimental observations.
An additional mode, characterized by vortex shedding from the leading edge,
appears to be related to a hydrodynamic absolute instability. We discuss
criteria that we have developed to predict its onset. We also show results for
modeling of the shear layer mode, comparing DNS results to
models based on linear stability theory and the Proper Orthogonal Decomposition.
Both models show good promise for capturing the basic flow physics at
low order. Some recent results from a labratory experiment of a similar
phenomena will also be discussed.
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