Numerical investigation on vortex dipole interacting with concave walls of different curvatures

Immersed boundary lattice Boltzmann method is adopted to simulate Lamb vortex dipole colliding with concave walls of different curvatures. We introduce the single-relaxation-time lattice Boltzmann method and a variant of the immersed boundary method (IBM). The present IBM avoids the penetration phenomenon of streamlines through the solid wall. The formation of Lamb vortex dipole is simulated subsequently. Focusing on dipole-wall interactions, vortex dipoles colliding with concave walls of different curvatures at three Reynolds numbers Re = 800, 1600 and 2400 are simulated. Circulation and the track of the positive monopole from initial vortex dipole are used to investigate the features of dynamics process. The results show that the circulation ratio of the secondary vortex pair reduces as the curvature of the concave wall decreases. The results also indicate that there exists certain threshold of curvature, out of which the dynamic characteristics of the vorticity field changes apparently.