Theflow under influence of magneticfield is experienced in cooling electronic devices and voltage transformers, nuclear reactors, biochemistry and in physical phenomenon like geology. In this study, the effects of magneticfield on theflowfield, heat transfer and entropy generation of Cu–water nanofluid mixed convection in a trapezoidal enclosure have been investigated. The top lid is cold and moving toward right or left, the bottom wall is hot and the side walls are insulated and their angle from the horizon are 15°,30°,45°and 60°. Simulations have been carried out for constant Grashof number of 10 4 , Reynolds numbers of 30, 100, 300 and 1000, Hartmann numbers of 25, 50, 75 and 100 and nanoparticles volume fractions of zero up to 0.04. Thefinite volume method and SIMPLER algorithm have been utilized to solve the governing equations numerically. The results showed that with imposing the magneticfield and enhancing it, the nanofluid convection and the strength offlow decrease and theflow tends toward natural convection andfinally toward pure conduction. For this reason, for all of the considered Reynolds numbers and volume fractions, by increasing the Hartmann number the average Nusselt number decreases. Furthermore, for any case with constant Reynolds and Hartmann numbers by increasing the volume fraction of nanoparticles the maximum stream function decreases. For all of the studied cases, entropy generation due to friction is negligible and the total entropy generation is mainly due to irreversibility associated with heat transfer and variation of the total entropy generation with Hartmann number is similar to that of the average Nusselt number. With change in lid movement direction at Reynolds number of 30 the average Nusselt number and total entropy generation are changed, but at Reynolds number of 1000 it has a negligible effect
کلید واژگان :Nanofluid Entropy generation Magneticfield Trapezoidal enclosure Variable properties
ارزش ریالی : 600000 ریال
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