Numerical investigation of fully developed fluid flow and heat transfer in double-trapezoidal microchannels

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Fully developed fluid and heat transfer characteristics of double-trapezoidal microchannels with constant wall temperature are numerically investigated in the slip flow regime by applying slip/ jump conditions. The governing equations are solved together with the appropriate boundary conditions using a finite volume method. The influence of rarefaction on the Poiseuille number, Po, and the Nusselt number, Nu, is studied in the range of Knudsen number, Kn, between 0 and 0.1. The effects of base angle, B, and aspect ratio, A, on the fluid flow and the heat transfer characteristics are also examined. The results reveal that the rarefaction and the cross-section shapes have prominent effects on these characteristics of double-trapezoidal microchannels. According to the results, the Poiseuille number decreases with increasing Kn, while the values of the Nusselt number completely depend on the impacts of the rarefaction and the fluid-surface interaction. Po and Nu decrease with aspect ratio when A<1, while the effect of aspect ratio on the Poiseuille number and the Nusselt number becomes unclear for those of A>1. Further, an increase in the base angle increases Po and Nu, but the increasing trend is less observable for the case of both B > 60 o and A < 1.67.