SHARP-INTERFACE PHASE-CHANGE MODEL WITH THE VOF METHOD
Proper resolution of phasic interfaces is a key requirement for performing direct numerical simulations (DNS) of multiphase flows. The Volume-of-Fluid method (VOF) represents the phases in terms of a cell-wise volume-fraction function. VOF can capture the interface in a sharp manner with subgrid accuracy, while being inherently mass conservative at the same time. For multiphase problems involving phase change, the temperature
field near the interface must also be resolved in a sharp way, accounting for interfacial jump conditions. Using an irregular stencil dependent on the interface position, the temperature gradients at the interface can be captured. In turn, they can be used for calculating interfacial mass transfer rate. In this work, a coupling of a sharp-interface phase-change model and the VOF method is developed. Both the interfacial position and the temperature field are resolved with subgrid accuracy. Mass source due to phase change is localised exactly at the interface and possible variability of the interfacial temperature is accounted for. Coupling with conjugate
heat transfer is implemented and subgrid interfacial profiles in the vicinity of the solid are explicitly captured.
The methodology implementation is verified and validated using standard benchmarks. Simulations of rising bubbles and nucleate boiling are used for validation for problems involving phase transition. To the best of authors' knowledge, there has not yet been an attempt to validate a sharp phase-change model with a geometric VOF interface tracking method. Therefore, this work represents another step towards high-fidelity DNS of flows with phase transition.