Acoustic response of turbulent cavity flow using resolvent analysis

TL;DR

This paper uses resolvent analysis combined with Doak's momentum potential theory to decompose and understand flow-acoustic interactions in turbulent cavity flows at different Mach numbers, aiding flow control strategies.

Contribution

It introduces a novel input-output framework combining resolvent analysis and momentum potential theory for flow-acoustic decomposition in cavity flows.

Findings

Strong acoustic components appear at the cavity's trailing edge at low frequencies.

Increasing frequency causes acoustic structures to move upstream and overlap with hydrodynamic components.

Streamwise velocity forcing yields the highest energy amplification, especially near the leading edge.

Abstract

The decomposition of hydrodynamic and acoustic components of cavity flows can aid the understanding of the flow-acoustic interaction, which produces a variety of adverse effects in applications. We apply the approach of combining the resolvent analysis and Doak's momentum potential theory to examine the input-output flow-acoustic characteristics of compressible flow over an open cavity at Re=10,000. The methodology can decompose hydrodynamic and acoustic components from an input-output framework. We further localize the forcing at the leading-edge and front wall of the cavity and filter with a single component of velocity, density, and temperature forcing. For the subsonic flow at M=0.6, The strong acoustic component appears at the trailing edge of the cavity at a lower frequency. while as the frequency increases, the intense acoustic structure moves close to upstream and overlap with the hydrodynamic component. This tendency is also observed in the supersonic flow condition M=1.4. Compared to different types of forcing, the streamwise velocity forcing achieves the largest energy amplification. However, it substantially reduces by moving the forcing location from the leading-edge to the front wall of the cavity. This work provides an alternative approach to examine input-output flow-acoustic characteristics where resonance is dominant and provides guidance for the development of flow control strategies.