Heat transfer in ferrofluid with cylindrical shape nanoparticles past a vertical plate with ramped wall temperature embedded in a porous medium

This paper studies magnetogydrodynamic (MHD) and porosity effects on ferrofluid over an oscillating plate with time dependent wall temperature. Nanoparticles of cylindrical shape are contained inside the base fluids. Kerosene oil is chosen as conventional base fluids. Two types of nanoparticles, magnetite (Fe3O4) and non-magnetic (Al2O3) are added to the base fluid. The flow is unsteady and the ferrofluid is considered as an electrically conducting due to a uniform magnetic field applied in a perpendicular direction to the plate. The problem is modelled in terms of partial differential equation with some physical conditions and solved by using the Laplace transform technique. Exact solutions are obtained for velocity and temperature for both cases of time dependent and isothermal wall temperatures. Graphs of velocity and temperature for time dependent and isothermal wall temperatures are plotted and compared. It is found that under time dependent wall temperature condition, velocity and temperature are smaller in magnitudes than those obtained under isothermal wall temperature condition. Moreover, effects of porosity and Hartmann number are studied graphically and discussed. A comparison is also made between magnetite (Fe3O4) and non-magnetic (Al2O3) nanoparticles. Expressions for skin-friction and Nusselt number are computed in tables. Excellent agreement of the present results is found with existing results in the literature. In this work, cylindrical nanoparticles are chosen because of their abundant applications in biology and medicine. For instance, cylindrical nanoparticles are seven times more deadly than traditional spherical nanoparticles when delivering drugs to breast cancer cells. (C) 2016 Elsevier B.V. All rights reserved.