Analyses of Phase Change Separation Phenomenon in Flush Tank Using Volume of Fluid Method

Abstract

In this paper the simulation on flush tank is solved by Navier-Stokes equations with modified k - ε turbulence model with realizable RNG equation. The performance of the flushevaluated with the three-dimension flushing flow simulating method through the distribution of the twophase flow field, the total flow pressure, the flow speed at the surface and the siphoning bent tube.Those parameters have provided a high efficiency approach to develop new watersaving flush tank for commercial application.The recirculation zone and bubble under various boundary conditions (including adiabatic and non-adiabatic boundary conditions) using numerical simulations have been studied. On analyzing the multiphase flow, it can be seen that while considering fluid alone, phase separation is more at the outlet than at the inlet of tank. In the run arm phase separation is negligible due to the effect of gravity. Under the same initial flow conditions, wake downstream of the wave is found to be much more turbulent than that of the circular one. In addition, as Re increased, the turbulence of the wake flow increased and its length downstream of the wave increased.