Resumen: [EN] Bubble dynamics is generally described by the well-known Rayleigh-Plesset (R-P) equation in which the bubble
pressure (or equivalently the bubble density) is predefined by assuming a polytropic gas equation of state with
common assumptions to include either isothermal or adiabatic bubble behaviour. The present study examines the
applicability of this assumption by assuming that the bubble density obeys the ideal gas equation of state, while
the heat exchange with the surrounding liquid is estimated as part of the numerical solution. The numerical model
employed includes the solution of the Navier-Stokes equations along with the energy equation, while the liquidgas
interface is tracked using the Volume of Fluid (VOF) methodology; phase-change mechanism is assumed to
be insignificant compared to bubble heat transfer mechanism. To assess the effect of heat transfer and gas
equation of state on bubble behaviour, simulations are also performed for the same initial conditions by using a
polytropic equation of state for the bubble phase without solving the energy equation. The accuracy of
computations is enhanced by using a dynamic local grid refinement technique which reduces the computational
cost and allows for the accurate representation of the interface for the whole duration of the phenomenon in which
the bubble size changes significantly. A parametric study performed for various initial bubble sizes and ambient
conditions reveals the cases for which the bubble behaviour resembles that of an isothermal or the adiabatic one.
Additional to the CFD simulations, a 0-D model is proposed to predict the bubble dynamics. This combines the
solution of a modified R-P equation assuming ideal gas bubble content along with an equation for the bubble
temperature based on the 1st law of thermodynamics; a correction factor is used to represent accurately the heat
transfer between the two phases.
