Lattice Boltzmann simulation of nucleate boiling in micro-pillar structured surface

Abstract

A two-particle distribution functions lattice Boltzmann method is used to simulate periodic bubble nucleation, growth and departure from a micro-pillar structured surface. Bubble growth process and the effects of micro-pillar character scales on bubble departure period are investigated in this paper. Fluid hydrodynamic and thermodynamic are characterized by the density distribution function and the temperature distribution function respectively. Pseudo-potential model and Peng-Robinson equations of state are selected in our simulations. Constant temperature boundary condition is applied to the bottom solid. It is found that bubble generated in the vicinity of the micro-pillars, but in the same superheat, the smooth surface has no phase change phenomenon. This result indicates that micro-structure can contribute to the nucleation of the fluid phase change. Geometrical dimensions of micro-pillars have obvious effects on the growth of the bubble. Specifically, we investigated the influence of the distance between two pillars and the height of the pillars on the bubble growth. Results show that, to some extent, the distance of two micro-pillars “n” and the height of micro-pillar “h” have obvious effects on the bubble growth. For the height “h”, the smaller of “h”, the bigger of heat flux and the smaller of bubble departure periodic. For the distance “n”, it has no obvious effect on surface heat flux and bubble departure periodic but has an important effect on deciding whether it can form an activated nucleate site. Only proper “n” and “h” can be chosen to ensure an activated nucleation site according to our simulation results.