Numerical Investigation on Collapse Dynamics of Near-Wall Bubbles under Elliptical Surface Boundaries Conditions

Bubble dynamics near complex boundaries is critical for engineering applications like underwater explosions and cavitation control. This study investigates the collapsing behavior of near-wall bubbles adjacent to three boundary conditions (planar, elliptical convex, and elliptical concave surfaces) using a compressible multi-component flow model. The finite volume method combined with fifth-order Weighted Essentially Non-Oscillation (WENO) reconstruction and the Harten-Lax-van Leer Contact (HLLC) Riemann solver is employed for spatial discretization, while the third-order Total Variation Diminishing (TVD) Runge-Kutta scheme handles temporal discretization. Results show that elliptical convex and concave surfaces exhibit opposite regulatory effects: the convex surface accelerates bubble collapse, reduces oscillation periods, and increases the water jet pressure peak, whereas the concave surface delays collapse, prolongs periods, and decreases pressure peaks. With increasing stand-off distance ratio, bubble oscillation periods decrease, and minimum equivalent radii also reduce for all boundaries. This work provides insights into complex boundary-induced bubble dynamics, supporting the optimization of cavitation-resistant structures and underwater explosion protection.