Comparative analysis of turbulence structure in near-wall and midplane regions of a high-Reynolds-number lid-driven rectangular cavity

The lid-driven cavity flow is a classical benchmark for validating computational fluid dynamics models and investigating turbulence mechanisms. However, most previous studies have focused on the midplane (x/D = 0.5), while systematic measurements of the near-wall plane (x/D = 0.2), which is directly affected by wall confinement, remain scarce. This limitation hinders a comprehensive understanding of three-dimensional turbulence in confined cavity flows. In this study, particle image velocimetry was adopted to conduct synchronized, high-resolution measurements on both the near-wall plane and midplane of a rectangular cavity over a high Reynolds number range from 1.161 × 105 to 3.483 × 105. The experimental results show that, compared with the midplane, the primary vortex core on the near-wall plane shifts rightward by approximately 40% with a displacement coefficient of 0.71–0.76. Flow statistics indicate that the near-wall plane exhibits a significantly lower mean velocity, and the proportion of low-velocity regions (<0.04 m/s) is about 7%–10% higher than that on the midplane. Under moderate and high Reynolds number conditions, the peak turbulent dissipation rate near the wall increases by a factor of 1.1–1.2. In addition, spanwise cross section analysis demonstrates that the primary vortex core on the mid-span plane (y/D = 0.5) retains the classic low-velocity vortex feature, whereas the near-end wall plane (y/D = 0.2) transforms into a local high-momentum concentration zone within the vortex core due to the combined effects of end wall confinement and secondary flows, highlighting a pronounced three-dimensional flow reconfiguration. This work provides the first systematic experimental evidence for the fundamental differences in turbulent characteristics between the near-wall and midplane of a rectangular cavity. These findings establish critical experimental benchmarks for the distribution of turbulent kinetic energy production and dissipation, which are essential for validating the accuracy of models such as the wall-adapting local eddy-viscosity (WALE) model in wall-confined asymmetric flows and guiding engineering optimizations.