Pressure characteristics of bubble collapse near a rigid wall in compressible fluid

• BEM and LS-MGF-DG method are combined to study pressure characteristics of a bubble near a rigid wall in compressible fluid.
• An experiment of a spark-generated bubble near a steel plate is conducted to validate the numerical model.
• The bubble-collapse shock wave with a higher pressure value may cause a wider damage to a structure than the bubble jet.
• Due to bubble rebound and bubble splitting, a third peak of the pressure wave occurs at the center of the rigid wall.
• Three pressure peaks due to bubble jet, collapse and rebounding and splitting decline with the rise of the standoff distance.

High speed liquid jet and shockwave can be produced when a bubble collapses near a rigid wall, which may cause severe damage to solid structures. A hybrid algorithm was adopted to simulate bubble motion and associated pressures near a wall combining Level Set-Modified Ghost Fluid-Discontinuous Galerkin (LS-MGF-DG) method and boundary element method (BEM). Numerical results were compared with experimental data to validate the presented algorithm. Jet formation was simulated by BEM and the induced pressure on the wall was calculated with auxiliary function. The pressure at the point on the wall where the jet points to reaches its peak value after the jet penetrates the bubble. Bubble collapse and rebounding were simulated by the LS-MGF-DG method. Shock-wave is induced when the bubble collapse toroidally to a minimum volume and the pressure at wall center reaches the maximum due to shockwave superposition. A third pressure peak is found associated with the bubble rebounds and bubble splitting. In the case studied, a higher pressure was found due to collapse shockwave than bubble jet and affects a larger area of the wall. In addition, the three pressure peaks due to jet impact, collapse impact as well as bubble rebounding and splitting decrease with the increase of the standoff distance.