SIngularity influences jet direction during the collapse of bubbles in contact with walls

Bubble dynamics in contact with walls have applications in diverse areas of industrial cleaning, biomedical sciences and underwater explosions among many others. In this work we theoretically and numerically study the collapse of a single bubble sitting at a wall after an impulsive change of the ambient pressure. The flow is decomposed as sum of potential and a viscous field. The potential field, obtained from the solution of the Laplace equation, exhibits singular solutions at the contact point for contact angles larger than 90 degrees that are shown to describe well the overall dynamics of the bubble collapse process obtained from DNS. In particular, we describe the appearance of a jet developing parallel to the solid wall that ultimaly leads to a jetting process in the opposite direction to the solid boundary. Viscosity is shown to regularize the flow near the singular point and contol the finite jet velocities.