Evaluation of viscous dissipation in liquid flow in microchannels

Abstract

Different phenomena have been observed in various works indicating that the mechanisms of flow and heat transfer in microchannels are still not understood clearly. There is little experimental data and theoretical analysis available in the literature to elucidate the mechanisms. It is reasonable to assume that, as the dimensions of flow channels approach the micro-level, viscous dissipation could be too significant to be neglected due to a high velocity gradient in the channel. However, no evidence and analysis was presented to verify such an explanation. Therefore, in this paper, the effects of viscous dissipation in microchannel flows are analyzed and examined theoretically. A criterion to draw the limit of the significance of the viscous dissipation effects in the microchannel flows is suggested based on the present analysis.