Flow topology and vortex dynamics of transient flow in a three-dimensional semi-circular cavity

This study endeavors to investigate the transient flow topology and corresponding vortex dynamics in a three-dimensional semi-circular cavity. We first analyze the flow on the cross-flow plane passing through the vortical coreline in the transitional regime, examining the instantaneous flow topology near the stationary walls. We also observe the presence of Taylor–Görtler-like vortices near the bottom of the cavity. Subsequently, the three-dimensional streamwise vortices are identified using the λ2 criterion and further validated using various first-, second-, and third-generation vortex identification methods. To gain the quantitative insight of the present study, we further explore the temporal evolution of volume-averaged kinetic energy and enstrophy over a fixed interval of time, clearly capturing the evolution of vortical structures. Finally, the dissipation contours reveal that the curved bottom wall corresponds to the strong shear layers and intense vortex interactions within the transitional flow regime.