Numerical Analysis About the Influence of Inappropriate Shape of the Cross-Section of Microchannels in Laminar Flow

Abstract

In the past decades, several experimental investigations performed to the hydrodynamics and heat transfer in microscale laminar flow have showed divergences to the Darcy friction factor and the Poiseuille and Nusselt numbers, when the results obtained for the same ones were compared to those provided by classical theory. There are reports of deviations to the Darcy friction factor and the Poiseuille and Nusselt numbers attributed to geometric imperfections at the cross-section of the microchannels. The aim of this numerical study is to analyze how the hydrodynamic and heat transfer characteristics in single-phase laminar flow, of a fluid with constant thermophysical properties, can be affected by imperfections at the cross-section of the microchannels. The results obtained for single-phase laminar flow of water in microchannels with imperfections at the cross-section are compared to those obtained for a geometrically perfect microchannel through Poiseuille and Nusselt numbers. Deviations at Poiseuille and Nusselt numbers due to imperfections at the cross-section of the microchannels were verified. The results showed that Nusselt number is more sensitive to shape of the cross-section of the microchannels than Poiseuille number. This study showed that knowledge about the geometrical shape of the cross-section of the microchannels is important to determine properly the hydrodynamic parameters of the flow, such as Poiseuille number. This study was carried out through computational fluid dynamics (CFD) and the numerical model made up by mass conservation, Navier-Stokes and energy equations.