Influences of electrical conductivity of the cylindrical walls on heat transfer enhancement of nanofluid swirling flow

Abstract

The swirling nanofluid flow driven by a revolving bottom disk of a cylindrical container under magnetic field effect and temperature gradient is examined in this study. The effects of the electrical conductivity of cylindrical walls’ on heat transfer enhancement are quantitatively investigated. The finite volume approach is used to solve the governing equations under the appropriate assumptions. This study considers four cases of combined electric conducting and insulating walls. The solid nanoparticle (copper) with volume fraction (ϕ = 0.1) is added to water. Calculations were done for fixed Reynolds number (Re=1000), Richardson number (0≤Ri ≤2), and various Hartmann numbers. The mean Nusselt number decreased as the Richardson number increased owing to stratification layers. These latter restrict heat exchanges between the cylinder’s hot and cold zones. The results show that within a particular range of Hartmann numbers, the Nusselt number increases, especially when the revolving lid is electrically conducting. The best heat transfer occurs when all of the walls are electrically conductive, which results in a 100% improvement at low Richardson values. Finally, the electrical conductivity of the revolving lid was a key factor in enhancing heat transfer.