Flow of water conveying Fe3O4 and Mn–ZnFe2O4 nanoparticles over a rotating disk: Significance of thermophoresis and Brownian motion

Abstract

Motivated by the applications of ferrofluids in electronic devices, spacecraft, and rotating shaft sealing in hard disks, etc.; a numerical study is characterized for unsteady Von-Karman flow of water-based nanofluid containing ferromagnetic (Fe3O4 & Mn–ZnFe2O4) nanoparticles over a rotating disk. The temperature-dependent viscosity of ferrofluid is considered in the present formulation. Additionally, Brownian motion and thermophoresis features are utilized to visualize the energy and mass transport characteristics. The fundamental mathematical flow model is rendered into a dimensionless system of non-linear equations via similarity variables, and the numerical results are obtained in the framework of the BVP Midrich method with the help of Maple programming. It is obtained that the (Mn–ZnFe2O4+water) ferrofluid achieves a more excellent radial velocity value than (Fe3O4+water), for ascending values of the stretching parameter. Also, the thickness of the thermal boundary layer is substantially depleted with a rise in the FHD interaction parameter. Conclusively, it is noted that due to strong thermal properties, the ferrofluid (Fe3O4+water) is more efficient in thermal conductance as compared to the other ferrofluid (Mn–ZnFe2O4+water).