Measurement of the velocity–pressure-gradient tensor of a turbulent shear layer flow impinging on a cavity trailing corner using time-resolved tomographic PIV

We measure the three-dimensional pressure-related turbulence terms i.e., the velocity–pressure-gradient tensor, which can be decomposed into the pressure–rate-of-strain, and the pressure diffusion tensors based on 35,163 realizations obtained by time-resolved tomographic PIV. The measurements were performed at the impinging area of a turbulent shear layer flow over a cavity at a Reynolds number of 4.0×10⁴ with a sample rate of 4500Hz. The interrogation volume used was 32×32×32 voxels with a 75% overlap resulting in a vector spacing of 0.21mm. The 3D instantaneous pressure distribution was obtained by the rotating parallel ray omnidirectional integration method. The quality of the measured pressure is assessed by checking the curl-free property of the pressure gradient, as well as the zero-sum property of the inter-component energy transfer represented by the summation of the normal pressure-strain terms, i.e., R₁₁+R₂₂+R₃₃=0. The continuity equation is used to assess the quality of the velocity measurement. The overall balance of the Reynolds stress transport equation is also examined. This is the first time that the 3D pressure-related turbulence transport terms around the cavity trailing corner is fully characterized, following the work of Liu and Katz (2018) based on planar-PIV.