Entropy generation investigation of nanofluid flow in the ribbed rectangular channel under magnetic field

The main objective of this paper is to investigate parameters of heat transfer and fluid flow of Ag-water nanofluid through a ribbed rectangular channel in the presence of a magnetic field. The walls of the channel are exposed to constant heat flux. The study is carried out at four different Reynolds numbers (10 < Re < 500). Also, the Hartmann numbers and nanofluid volume fractions are changed in the range of 0-200 and 0-0.04, respectively. The effect of variation of Reynolds numbers, Hartmann numbers, and nanofluid volume fraction is analyzed on the local Nusselt number, average Nusselt number, entropy generation, and profiles of velocity. The result indicated that there is a critical Reynolds number that leads to minimum entropy generation at all volume fractions of nanoparticles and Hartmann numbers. At higher Hartmann numbers, velocity profiles become flattened, and the heat transfer increased. Thermal performance is approximately enhanced three times with the Reynolds number increase. At high Reynolds numbers, magnetic field force is caused the total entropy generation rate's increase to five times. But at low Reynolds numbers, magnetic field force has not sensible effect on total entropy generation rate.