Abstract
Erosion due to high-speed droplet impact is caused by the water-hammer loading on the material surface and possibly by the reloading from collapsing cavitation bubbles that appear within the droplet. Here, we simulate the dynamics of cavitation bubbles accompanied by high-speed droplet impact in order to see whether the bubble collapse is violent enough to account for cavitation erosion on the surface. The evolution of pressure waves in the water droplet to collide with a deformable wall is inferred from simulations of multicomponent Euler flow where phase changes are not permitted. For simplicity, we perform Rayleigh-Plesset-type calculations in one-way-coupling manner; namely, the bubble dynamics are determined according to the pressure variation obtained from the Euler flow simulation. In the simulation, the preexisting, submicron-sized nucleus show bubble growth because tention in the liquid is obtained through interaction of the pressure waves and the droplet interface; this supports the possibility of having cavitation due to the droplet impact. It is also found that radiated pressure from collapse of the cavitation bubble is comparable to the water-hammer pressure created by the initial impact of the droplet. Hence, cavitation may need to be accounted for when it comes to discussing erosion in the droplet impact problem.
