  We present a new approach to studies of bubble dynamics in fluids. Relying on
particle-based simulations, this method is general and suitable for cases where
the commonly used perfect fluid description fails. We study expanding true
vacuum bubbles surrounded by free or self-interacting particles and quantify
how self-interactions affect the terminal bubble wall velocity. We find that,
for sufficiently strongly self-interacting fluids, local thermal equilibrium is
maintained around the bubble wall and the fluid profile is similar to that
obtained with the perfect fluid description.
