NUMERICAL INVESTIGATION AND ANALYSIS OF HEAT TRANSFER ENHANCEMENT IN A MICROCHANNEL USING NANOFLUIDS BY THE LATTICE BOLTZMANN METHOD

摘要

In this work, heat transfer enhancement in a microchannel using water-Ag nanofluid has been investigated numerically by the lattice Boltzmann method (LBM) by adopting the stream and collide algorithm, with the (BGK) approximation. The base fluid and the suspended nanoparticles are considered as a homogeneous mixture. And a single phase model with first-order slip and jump boundary conditions has been adopted. Thermophysical properties of water-Ag nanofluid are estimated by the theoretical models. Effects of change in nanoparticle volume fractions, Reynolds number and Knudsen number are considered. It was concluded that change in nanoparticle volume fractions did not have significant effects on velocity slip. Whereas the temperature jump was significantly influenced. And increasing nanoparticle volume fractions leads to an increase in Nu. However, increasing Kn resulted in less Nu and a decrease in the skin friction CfRe. The average Nusselt number is enhanced by 12.3% for a particle volume fraction of 4% compared with that of pure water at Re=3.19. And the effect of Re is especially important at higher volume fractions.