Investigation on boundary schemes in lattice Boltzmann simulations of boiling heat transfer involving curved surfaces

Abstract

The lattice Boltzmann (LB) method has been applied to simulate boiling heat transfer in recent years. However, the existing studies are mostly focused on boiling on flat surfaces or structured surfaces with square pillars/cavities, and very few LB studies have been made regarding boiling on curved surfaces. In order to clarify the issues involved in the curved boundary implementation for boiling simulations, we numerically investigate the performances of two LB boundary schemes in simulating boiling on curved surfaces. One is the halfway bounce-back scheme, which is very popular in the LB community because of its easy implementation, and the other is a curved boundary scheme. Numerical results clearly show that the halfway bounce-back scheme leads to "artificial"nucleation sites in simulating boiling on curved surfaces because of its staircase approximation. A curved boundary scheme can overcome such a drawback, but it yields serious mass leakage. Hence, a mass-conservation correction should be enforced to the curved boundary scheme so as to eliminate the mass leakage in boiling simulations. The present study indicates that the halfway bounce-back scheme is not suitable for the LB simulations of boiling involving curved surfaces, while the curved LB boundary schemes must be combined with a mass-conservation correction when applied to simulate boiling on curved surfaces.