In the present simulation, a solver called phaseChangeHeatFoam is implemented under open source CFD code OpenFOAM to consider boiling and condensation. The solver is capturing interface among two immiscible phases using a color function volume of fluid. The two fluids (vapor and liquid) are assumed Newtonian and incompressible. The surface tension between liquid-vapor phases is accounted using
... [Show full abstract] continuous surface force (CSF) model. The spurious current in CSF model is reducing using filter and s-CLSVOF method. The mass flux rate across the interface is determined by Lee, Tanasawa or Fourier mass transfer models in the present attempt. Additionally, the variation of saturation temperature with local pressure is considered with Clausius-Clapeyron relation. The coupled velocity pressure equation is solved using PISO algorithm.
Our studies show the spurious current is reduced up to 1 order in the simulation of stagnant bubble problem using present implemented methods. These methods also increase the accuracy of pressure jump calculation. Additionally, the present comparison shows not only filter method is simple to implement but also it is as efficient as s-CLSVOF method in calculation of curvature and reducing spurious current. The new solver is validating with (i) Stefan problem, (ii) two-dimensional film boiling, (iii) the film condensation on horizontal plate, (iv) the laminar film condensation over vertical plate. To estimate the accuracy of present solver in different conditions, saturation water at different saturation pressures are chosen up to high density ratio of 1000. The comparison between present numerical simulations and analytical solutions and previous sharp interface method simulations shows present solver has a high accuracy in simulation of phase change flow despite of using diffuse interface method (DIM). Then phase change phenomena in vapor bubble rising in subcooled and saturated liquid are studied and compared with available experimental data. Our numerical studies show bubble life time has linear relation with bubble size but it is not dependent on initial bubble shape in subcooled fluid. There is a non-linear relation between bubble life time and subcooled temperature which is consistent with sudhoff correlation. Moreover, bubble survives longer in bubble swarm condensation due to being placed in the thermal boundary layer of up-front bubbles. The simulation of superheat vapor bubble in saturated water shows bubble size increases due to evaporation at first. However, it collapses finally due to condensation. Here, the bubble life time is proportional with vapor bubble superheat temperature. The present study shows the capability of diffuse interface method in accurate simulation of phase change process and gives some fundamental information about vapor bubble rising which is expected to be instructive for further applications.
