Modeling laser-generated cavitation bubbles

Cavitation in turbomachinery can impact performance and lifecycle. The formation and collapse of cavitating bubbles near a surface releases significant energy in a very short time often resulting in erosion damage. Considerable research has focused on understanding the physics of bubble formation and collapse, and how this collapse relates to surface erosion. To date this has been an elusive goal due to the process physics, flow and temporal scales and experimental and computational limitations. This research focused on developing a computational model of cavitation bubble formation and collapse to be used to develop erosion prediction tools. The dynamics associated with the formation of a laser-pulse generated bubble and its collapse against a solid wall was computationally modeled with OpenFOAM using a compressible multi-phase pressure-based solver. A conservation of energy model was developed to predict the localized heating occurring at the focal point of the laser. The temporal bubble dynamics - growth, collapse, rebound and associated flow characteristics of high speed re-entrant jet and high pressure waves were modelled as a function of bubble stand-off distance. Results were compared to published research. The model successfully computes bubble formation and collapse dynamics, re-entrant jet structure and magnitude, the associated pressure field, and sensitivity to stand-off distance.