The Problem with Vaping: Difficulties Modelling the Liquid-Gas Transition

The equation of state (EoS) provides simulations with knowledge of the pressure as a function of density and energy when solving the hydrodynamic equations. It is also advantageous for complex models to tabulate the EoS beforehand and use appropriate methods for interpolation and extrapolation to give a robust, accurate and time-efficient response.

An example of a complex model is a multiphase EoS; this includes an account of phase transitions, e.g solid-solid and solid-liquid. The liquid EoS also includes a liquid-gas phase transition, and when this is incorporated into the multiphase model it can never go into tension when in the liquid state. This raises questions about how to balance this with solid phases that can return negative pressures, and even whether it is better to neglect this effect in the liquid altogether and thus allow for an approximation of liquid spallation; in the absence of a sophisticated cavitation model.

This talk describes the implementation and difficulties observed while applying different treatments of the liquid-gas transition in the generation of a tabulated multiphase EoS. The various options are tested in a simulation of a recent tin shallow bubble collapse experiment.