Heat and mass transfer study of ferrofluid flow between co-rotating stretchable disks with geothermal viscosity: HAM analysis

Abstract

The investigation of ferrofluid flow in rotating disk systems has been increased due to the many engineering applications in rotating objects. Ferrofluids are greatly significant in sealing of rotating shafts in hard disk drives. For this reason, the ferrohydrodynamics flow, heat, and mass transfer characteristics of a fluorocarbon-based magnetic nanofluid (FC-72) between two coaxial rotating stretchable disks have been examined. Both lower and upper disks are stretchable, and the viscosity of magnetic nanofluid (MNF) is directly proportional to the linear function of depth and inversely proportional to the linear function of temperature. Moreover, the heat transfer process is carried out with the viscous dissipation effect. An approach of similarity transformation is used to convert the obtained fundamental equations into a non-dimensional system of equations. The semi-analytic homotopy analysis method is executed to obtain the convergent series solution of a non-dimensional system of equations. Mathematica package BVPh 2.0 based on HAM is applied to plot the solution of dimensionless differential equations. The behavior of influential parameters, namely, viscosity variation, rotation, ferrohydrodynamic interaction, radiation, Prandtl number, Eckert number, and Reynolds number, on the flow regimes are shown graphically. It is obtained that the magnitude of horizontal velocity reduced in the vicinity of lower disk for increasing value of viscosity parameter γ1. Fluid temperature magnitude and nanoparticle concentration are increasing functions of Reynolds number.