Study on Nusselt Number Characteristic in Rarefied Micro/Nano Channels Geometry

Accurate modeling of gas dynamic and thermodynamic is crucial for a lot of MEMS applications (micro heat exchangers, fluidic micro actuators for active control of aerodynamic flows and microsystems). Gas flows in microsystems are often in the slip and transition flow regime, characterized by rarefaction with Knudsen number. In these regimes, velocity slip and temperature jump at the walls play a major role in heat transfer. This paper numerically investigates convective heat transfer in rarefied laminar flow micro channels, focusing on Nusselt number under constant wall heat flux condition. Direct Simulation Monte Carlo (DSMC) Method is used as numerical solver. The effects of rarefaction (Knudsen number, Kn), and viscous dissipation (Brinkman number, Br) on Nusselt number are taken into account in this paper. Investigations show that the Nusselt number decreases when Knudsen and Brinkman number increase in both slip and transition regime. But it is less dependent to Knudsen number at higher Kn. Also it is shown that Nusselt number increases with increase in wall heat flux.

کلیدواژه ها:

DSMC ، Nusselt Number ، micro/nano channel ، rarefied flow