ID 344

Numerical accuracy of incompressible phase change simulations

 

Abstract:

High-fidelity simulations of fluid flow involving phase change have recently become a popular subject in the literature due to their relevance in heat transfer and energy-related fields. These simulations are based on implicit interface capturing involving either level set, VoF, or its many variants. They endeavor at describing the phase change process by directly imposing the associated jump conditions rather than adopting coarse-grained models. In the vast majority of these high-fidelity simulations, the incompressibility assumption is invoked in both the gas and liquid phases. This assumption is tested in the present work by adopting the canonical bubble growth/collapse configuration and by employing two codes: (i) a Gradient-Augmented Level Set methodology, and (ii) spherically-symmetric compressible treatment of the phase change process. It is shown that for bubble growth cases, which are parametrized by the Jacob number, the incompressibility assumption is adequate, and there is no need to treat the gas phase in a compressible manner. However, for the collapse cases, parametrized by the non-dimensional number B (introduced by Florschuetz & Chao, 1965), it is shown that beyond a given threshold value, the collapse introduces compressibility in the gas phase, and at an even higher value of B, both phases become compressible. The reasons controlling this behavior are analyzed and reported.