Impact loads generated by tandem cavitation bubble on solid wall

Experiments on two cavitation bubbles, which are generated at the same instant, with three different sizes near solid wall are conducted and their impulses on the boundary are registered by polyvinylidene fluoride (PVDF) sensor. Due to being near the boundary, bubble interactions and deformed features are in contrast with those in infinite fluid medium. In this paper, five morphologies of bubble deformation during growth and collapse phases are observed by high-speed camera. These profiles are strongly influenced by inter-bubble distance (η), stand-off distance from boundary (γ), and bubble size differences. Analysis of photographs coupled with sensor measurements enabled qualitative investigation of two bubble interactions on the boundary. From sensor data acquisition, it is confirmed that lower bigger bubble with upper smaller bubble configuration produces highest impulses on the boundary compared with other vertical arrangements of the tandem cavitation bubble employed in this study.