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Ch. Lechner, M. Koch, W. Lauterborn, R. Mettin:
"Numerical results for the collapse of laser-generated cavitation bubbles with varying initial distance from a solid boundary";
Talk: Drittes Kolloquium Kavitation und Kavitationserosion, Bochum; 2018-11-06 - 2018-11-07.

Cavitation bubbles collapsing close to solid boundaries have been subject to
intense investigations for several decades. In particular,
laser-generated cavitation bubbles have been used to study the
bubble dynamics and the mechanisms of their destructive action on
the solid wall as a function of the normalized initial distance $D^*$
in a systematic way.

In this talk we present results from numerical simulations modeling the
collapse and rebound of laser-generated cavitation bubbles with an initial
normalized distance $D^* \in [0.048,3]$ from a rigid wall.
The numerical model consists of a bubble filled with a small amount of
non-condensable gas in a compressible liquid obeying the Tait equation of
state. We use the volume of fluid method to capture the interface
between liquid and gas. The Navier Stokes equations are discretized with the
finite volume method. We have adapted a compressible two-phase solver from
the open source software package OpenFOAM \cite{OF-extend}
for our purpose.

We describe the dynamics of the bubble (jet formation and impact,
splitting of the torus bubble, first collapse, rebound, second collapse),
as well as
the pressure signal at the solid boundary as a function of $D^*$.
The numerical simulations can reveal details on the collapse
that are not, or not easily, accessible in the experiment,
as e.g.~the formation of a secondary sheet-like
annular jet.
The numerical results concerning bubble shape parameters, jet velocities
and pressure signals are compared to experimental data.