Modeling of the bubble collapse with water jets and pressure loads using a geometrical volume of fluid based simulation method

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The dynamic behavior of bubble collapses, water jets, and pressure loads during the collapse of the bubble near walls and a free surface were numerically investigated via a geometrical volume of fluid (VOF)-based simulation method. The numerical method is based on the compressible Navier–Stokes equations in a conservative form that describe the flow of compressible viscous fluids. The equations are discretized on a general curvilinear grid using an associated Godunov-type numerical scheme, and a reconstruction of a computational finite-volume Riemann solver is introduced for suppression of oscillation near the interface between fluids. The interface was tracked using the VOF reconstruction method. The VOF method is based on a geometrical tool and Lagrangian propagation of the interface reconstructed by a piecewise linear interface calculation (PLIC), resulting in strictly mass-conserving and sharp interface solutions. The numerical procedure was validated for capturing sharp interface and strong shock waves. For the simulation of bubble collapse, grid dependence studies of a spark-generated bubble were studies of both spherical and non-spherical bubbles were conducted. The results showed good agreement between the simulation and experiment of the bubble dynamics during the collapse process. Subsequently, an investigation of a single bubble near a wall with different standoff distances was performed. The pressure loads induced by the jets impacting the walls were calculated and analyzed. Furthermore, a more complex case of bubble collapse near an oblique wall and free surface was simulated. The resulting bubble dynamics with the jets and free surface shape were compared via photographs of the experiments.