Numerical study of time-dependent ferrofluid flow past a cylinder in the presence of stationary magnetic field

Abstract

This work investigates time-dependent ferrofluid flow past in a cylinder in the presence of a 10 kilo-ampere per meter magnetic field. The Reynolds number is about a hundred to keep the laminar flow and it is high enough to form a von Karman vortex street. This study presents the results for the velocity distributions, pressure distributions, lift coefficient, and drag coefficient under the influence of the stationary magnetic field. These results are compared with the flow in the absence of the magnetic field. The presence of the magnetic field diminishes the velocity distributions in the flow due to magnetization force and magnetic field dependent viscosity. This reduction in the velocity reduces the average velocity in the flow and therefore the magnetic field intensity enhances the coefficients of drag and lift. In the presence of the applied magnetic field, the velocity drops from 2.19 to 1.97 m/s at t = 7 s. However, the lift coefficients enhance from 3 m ²s ²/kg to 3.4 m ²s ²/kg and the drag coefficient enhances from 0.9 to 3 m ²s ²/kg. The numerical simulation of the problem is obtained using the finite element method in COMSOL Multiphysics.