Vortex ring impingement on wall-mounted convex half-cubes

Discrete vortex rings impinging on wall-mounted convex half-cubes with varying sizes were experimentally investigated at a fixed Reynolds number (Re = 1000). The side length (a) to the diameter of the circular orifice (d) includes a/d = 0.5, 1, 1.5, 2, 3. Using planar laser-induced fluorescence (PLIF) and particle image velocimetry (PIV), the upstream evolution was analyzed through vorticity, finite-time Lyapunov exponents (FTLEs) fields, and vortex core trajectories. The results show that vortex evolution and boundary layer separation are strongly influenced by surface geometry, especially sharp edges and curvature transitions. For small sizes (a/d ≤ 1), the vortex ring interacts with both the half-cube and wall, where edge-induced vorticity intensification accelerates the decay of primary vortex ring. At a/d = 0.5 and 1, stronger deformation and diffusion on Plane II lead to rapid coherence loss and fragmented FTLE ridges, suppressing the formation of tertiary vortex ring. For the intermediate size (a/d = 1.5), the interaction is confined to the half-cube, but the behavior of the primary vortex ring in the later stages of motion exhibits spatial heterogeneity. For larger sizes (a/d ≥ 2), the flow recovers canonical wall impingement patterns with symmetric secondary and tertiary vortex rings. These results clarify how sharp-edged convex geometries modulate vortex–boundary interactions and extend understanding of vortex ring impingement beyond smooth surfaces.