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.
Highlights
The lattice Boltzmann (LB) method, which is a mesoscopic numerical approach built on the kinetic Boltzmann equation, has been developed into an efficient numerical methodology for simulating fluid flow and heat transfer.1–8 The LB method has gained a number of advantages from being based on the Boltzmann equation rather than the Navier–Stokes equations
Despite the fact that considerable efforts have been made in applying the LB method to simulate boiling heat transfer, 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 conducted regarding the simulations of boiling on curved surfaces, which is mainly attributed to the fact that several issues involved in the LB boundary implementation for simulating boiling on curved surfaces have not been well addressed
The LB method has been extensively applied to simulate boiling heat transfer, but most studies are focused on boiling on flat surfaces or structured surfaces with square pillars/cavities
Summary
The lattice Boltzmann (LB) method, which is a mesoscopic numerical approach built on the kinetic Boltzmann equation, has been developed into an efficient numerical methodology for simulating fluid flow and heat transfer. The LB method has gained a number of advantages from being based on the Boltzmann equation rather than the Navier–Stokes equations. Gong and Cheng studied the boiling heat transfer on flat surfaces with mixed wettability using their phase-change model.. Gong and Cheng studied the boiling heat transfer on flat surfaces with mixed wettability using their phase-change model.19 They found that adding hydrophobic spots on smooth hydrophilic surfaces promotes bubble nucleation and reduces the nucleation time drastically. Li et al. numerically investigated the boiling heat transfer performance on a type of a hydrophilic– hydrophobic mixed surface, which is textured with square pillars consisting of hydrophilic side walls and hydrophobic tops. Ma et al. have recently investigated the boiling performances of four types of micro-pillar heat sinks with mixed wettability using the pseudopotential LB method. We aim at addressing the aforementioned issues by investigating the performances of the halfway bounce-back scheme and a curved boundary scheme in simulating boiling on curved surfaces.
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