Time-Resolved Simultaneous Measurements of Flow Field and Surface Deformation of Turbulent Channel Flow Over a Compliant Wall

As an initial step in our effort to investigate the interaction of a turbulent channel flow with a compliant wall, this paper focuses on the measurement techniques. Two noninvasive optical techniques, namely tomographic PIV (TPIV) and Mach-Zehnder Interferometry (MZI), are integrated to simultaneously measure the time-resolved, wall-normal deformation of the compliant transparent wall and the 3D velocity field of a turbulent channel flow above it. The two systems utilize the same laser, but different cameras. The paper provides a description of the optical setup, detailed information about calibration of the MZI system, as well as sample combined 3D velocity distributions and wall deformations. The measured wall deformation can be decomposed into low frequency structure modes, and higher frequency features that appear to advect with the flow.