Multiphase SPH modeling of water boiling on hydrophilic and hydrophobic surfaces

Abstract

A multiphase smoothed particle hydrodynamics (SPH) model was established to study the boiling phenomenon of a water film heated on a hydrophilic or hydrophobic surface. For the two-phase fluids of water vapor and liquid with continuous density gradient, conservation equations in Lagrangian formulation were discretized by SPH fluid particles. While the solid is treated by a new fluid-solid wetting surface model, which considered both the macroscopic interface curvature and the microscopic attractive forces. This SPH model enabled us to simulate the water boiling directly without empirical assumptions. After this model was well validated by three benchmark cases, we studied water boiling using two types of heating strategies. One strategy was partial heating with static or dynamic spots. The other was complete heating on an overall heating surface. Several fluid ρ-T phase diagrams were plotted with a detailed insight of the boiling development. We further simulated the critical heat flux (CHF) for both partial and total heating. The results illustrated the influences of the fluid thickness and the heating condition on the CHF value. The effects of wettability on boiling were also calculated. We found that a jumping boiling phenomenon would be observed on a relatively nonwettable surfaces, enhancing the heat exchange capability.