A numerical study on the effects of 2d structured sinusoidal elements on fluid flow and heat transfer at microscale

Better understanding of laminar flow at microscale level is gaining importance with recent interest in microfluidics devices. The surface roughness has been acknowledged to affect the laminar flow, and this feature is the focus of the current work to evaluate its potential in heat transfer enhancement. Based on various roughness characterization schemes, the effect of structured roughness elements on incompressible laminar fluid flow is analyzed and the hydrodynamic and thermal characteristics of minichannels and microchannels are studied in the presence of roughness elements using CFD software, FLUENT. Structured roughness elements following a sinusoidal pattern are generated on two opposed rectangular channel walls with a variable gap. A detailed study is performed to understand the effects of roughness height, roughness pitch, and channel separation on pressure drop and heat transfer coefficient. As expected, the structured roughness elements on channel walls result in pressure drop and heat transfer enhancements as compared to smooth channels due to the combined effects of area increase and flow modification. The current numerical scheme is validated with the experimental data and can be used for design and estimation of transport processes in the presence of roughness features. (C) 2012 Elsevier Ltd. All rights reserved.