Simultaneous Measurements of 3D Flow and Wall Deformation in a Compliant Wall Turbulent Channel Flow

This study focuses on the interaction of a turbulent channel flow at Re_τ=2310 over a flat, compliant boundary made of PDMS (Polydimethylsiloxane). Two noninvasive optical techniques, namely tomographic PIV (TPIV) and Mach-Zehnder Interferometry (MZI), are integrated to perform simultaneous measurements of the 3D flow field and the corresponding surface deformation. The measurements are performed in a refractive index-matched facility, where the working fluid is aqueous solution of sodium iodide (NaI). The TPIV measurement volume is 30×10×10 mm³ in the streamwise, wall-normal and spanwise directions, respectively. The MZI phase evaluation and unwrapping algorithms have been developed, calibrated and implemented. Preliminary results show qualitative correlation between wall deformation and flow structures near the wall.