10 / 2025-03-19 17:01:37

Study on the influence of rarefaction and compressibility on lid-driven cavity flow

lid-driven cavity flow,rarefaction,compressibility

This study investigates the impact of rarefaction and compressibility on lid-driven cavity flow using the conserved discrete unified gas kinetic scheme (CDUGKS), a method capable of capturing multiscale flow phenomena across all flow regimes. Through careful selection of initial and boundary conditions, we systematically analyze the individual and combined effects of three key dimensionless parameters: the Reynolds number (Re), the Mach number (Ma), and the Knudsen number (Kn). The Reynolds number is shown to play a pivotal role in determining vortex structures and the distribution of macroscopic quantities under varying degrees of rarefaction and compressibility. In rarefied flows, the increase in the mean free path of molecules reduces the frequency of intermolecular collisions, leading to non-equilibrium effects such as macroscopic slip velocity at the boundaries, modifications to secondary eddies, and deviations in the entropy generation rate from continuum flow predictions. Compressibility effects, on the other hand, induce significant variations in macroscopic quantities, including density and temperature, which in turn directly and indirectly alter the flow structure. Notably, changes in the density field enhance the efficiency of angular momentum transfer, resulting in the expansion of corner eddies. These findings provide new insights into the complex interplay between rarefaction, compressibility, and flow dynamics in lid-driven cavity flows.