NUMERICAL STUDY ON THE GROWTH AND COLLAPSE OF A CAVITATION BUBBLE INSIDE A RIGID CYLINDER WITH A COMPLIANT COATING

Cavitation bubbles are produced in a liquid flow when the static pressure is below the saturated vapor pressure. These bubbles move with liquid flow and violently collapse in high pressure regions. Violent collapse of the bubbles is believed to be one of the most important parameters in mechanical damage of hydraulic machineries and structures. They have also beneficial effects in medicine and Lithotripsy surgery. Experimental and numerical results show that during the collapse phase of a cavitation bubble near a rigid boundary a liquid jet is developed on the side of bubble far from the rigid boundary and directed towards the boundary. This liquid jet threads the collapsing bubble, creating a toroidal bubble. Cavitation bubbles behavior near various boundaries depends on material, dimension and shape of the surface and the bubble distance from the nearby boundary.In this paper, growth and collapse of a cavitation bubble inside a rigid cylinder with a compliant coating (a model of human’s vessels) are studied using Boundary Integral Equation and Finite Difference Methods. The fluid flow is treated as a potential flow and Boundary Integral Equation Method is used to solve Laplace’s equation for velocity potential. The compliant coating is modeled as a membrane with a spring foundation. At the interface between the fluid and the membrane, the pressure and normal velocity in the flow are matched to the pressure and normal velocity of the membrane using linearized condition.The effects of the parameters describing the flow (the fluid density, the initial cavity size and its position) and the parameters describing the compliant coating (the mass per unit area and spring constant) on the interaction between the fluid and the cylindrical compliant coating are shown throughout the numerical results. It is shown that by increasing the compliancy of the coating, the bubble life time decreases and the mass per unit area has an important role in bubble behavior.