Measurements of a turbulent boundary layer-compliant surface system in response to targeted, dynamic roughness forcing

Abstract

A series of experiments have been performed to study the response of a compliant (gelatin) surface to a turbulent boundary layer that has been forced by dynamic roughness. Through the synthetic flow structure generated by dynamic roughness, this work reduces the complexity of the fluid–structural problem in order to develop a fundamental framework with which to study flow control mechanisms. Flow velocity and surface deformations are measured using 2D particle image velocimetry and stereo digital image correlation, respectively. Both measurement methods are phase-locked to the roughness motion to allow the phase-averaged velocity and deformation fields to be isolated and correlated. The surface response of the non-dynamic roughness forced system is analyzed, and several spectral features are characterized. This analysis is used as context for the roughness forced deformations, subsequently confirming the response of the compliant surface to the synthetic flow mode. This demonstrates the potential of dynamic roughness experiments for studying flow control schemes and sets the stage for more detailed investigations of the effect of the compliant surface on the synthetic flow mode.