Thermo-hydrodynamics of single phase flow in microchannel with obstacles

Abstract

A numerical simulation has been carried out to understand the thermo-hydrodynamics of single phase flow with obstacle in microchannel. In this study, two different shapes of obstacle are analyzed with five different substrate materials to study the effect of thermal conductivity on the heat transfer. Uniform heating source is present at bottom wall of microchannel and remaining walls are kept adiabatic. The flow rate is maintained such that flow will be laminar theoretically. But under influence of obstacle, fluid is likely to get disturbed as it flows past the obstacle. So, both laminar and turbulent model was used in this analysis. The other factor is considered is the position of obstacle in the flow. The positions of obstacle affect the mixing of layer of fluid. Analysis revels that position of obstacle in the flow field directly affect the heat transfer. Disturbance created at the initial stage carried to long distance which enhance heat transfer coefficient. It is found that the temperature difference between wall and fluid increase along the axial direction of flow except near the obstacle. In analysis, it is found that shape of obstacle directly affect the Nusselt number, for half obstacle variation of Nusselt number increase vibrantly as compared to full obstacle. In case of laminar model, it does not take account of eddies formation near the flow. Nor it accounts the surface roughness. While in turbulent model, eddies formation near the surface can be seen which in turn increase Nusselt number, when simulating both full and half obstacle using both laminar and turbulent model, it is found that higher Nusselt number is found in case of turbulent model, hence Nusselt number is reach to maximum in turbulent in comparison to laminar model.