Shear/Pressure Sensors Characterization in Wall-Bounded Turbulent Shear Flow

Quantifying transient wall stress in shear-driven flows is essential for advancing understanding of near-wall turbulence and flow-surface interactions. To address this need, a high-resolution shear/pressure sensors are developed based on a WiMTiP (wrinkle-free metallic nm thin film in polymer) technology. The sensors enable simultaneous, full-field measurements of normal and shear strain with nanometer-scale sensitivity. The instantaneous strain deformation is interrogated using Digital Holographic Microscopy Interferometry. Calibration is performed in a rotating shear flow facility, where a rotating upper disk generates controlled wall shear over a stationary, transparent bottom plate housing the sensor. The system allows precise modulation of shear while preserving optical access for interferometric measurement. Results show spatial resolution, temporal responsiveness, and repeatability of the sensors, establishing a robust platform for future studies involving wall-bounded turbulence and unsteady surface stress environments.