Effect of Density Variation on Rarefied and Non-rarefied Gaseous Flows in Developing Region of Microtubes

Abstract

The present study analyzes the rarefaction and non-rarefaction effects on heat transfer characteristics of hydrodynamically and thermally developing air flow through microtubes having a constant wall heat flux boundary condition. The problem is especially simulated with two microtubes having diameters 50 µm and 150 µm. The rarefaction effect is taken into consideration using Maxwell slip flow and temperature jump boundary conditions. The fluid property variation is considered as a non-rarefaction effect which plays a significant influence on convection through a microtube. It is observed that the rarefaction and non-rarefaction effects significantly affect the convective heat transfer. The non-rarefaction effect decreases the Nusselt number (Nu) as compared to constant property solution; however, the rarefaction effect increases the Nu compared to constant property solution.