Numerical simulation of roughness effect on microchannel heat transfer and pressure drop in laminar flow

Roughness effects on the heat transfer and pressure losses in microscale tubes and channels are investigated through a finite element CFD code. Surface roughness is explicitly modelled through a set of randomly generated peaks along the ideal smooth surface. Different peak shapes and distributions are considered; geometrical parameters are representative of tubes in the diameter range from 50 to 150 µm. The use of a sufficiently fine mesh allows the direct computation of tube performances under the assumption of incompressible, fully developed flow; a comparison with the predictions of simplified models is also presented. As a result, in the present computations a significant increase in Poiseuille number is detected for all the configurations considered, while the effect of roughness on the heat transfer rate is smaller and highly dependent on the tube shape.