Connecting wall pressure fluctuations with flow structure over a backward-facing step using reduced order models

We analyze the flow over a backward-facing step to address the following question: Does the wall pressure signal contain information about the flow structure, and how do we capture it in a reduced-order model? We take Time Resolved Particle Image Velocimetry measurements synchronized with wall pressure in a water channel at Re_H ≅ 5100, where H is the step height. We use a variety of data analysis techniques, including cross-spectral power densities, Force Moment partitioning, and modal decomposition, to construct low-order predictive models of the separated flow. We identify spatial structures associated with specific frequencies that dominate the flow field. These tools will be used to construct an active surface with metamaterials to control the flow in the reattachment zone.