Heat transfer effect on the ferrofluid flow in a curved cylindrical annular duct under the influence of a magnetic field

Abstract

The current research, which can be employed in various engineering applications, is involved with the investigation of the heat transfer effect on the laminar and fully developed ferrohydrodynamic flow into a curved annular cylindrical duct, when a constant very strong transverse magnetic field is applied. The numerical solution of the involved constitutive partial differential equations, i.e. the continuity, momentum, energy, magnetization and Maxwell's equations with the corresponding boundary conditions, is achieved via the computational Continuity-Vorticity-Pressure (C.V.P.) algorithmic method, using a conveniently chosen non-uniform grid. The method is implemented via an in-house code, which has been applied and validated in several ferrohydrodynamic flows. It incorporates a general theoretical model for the magnetohydrodynamic flow of micropolar magnetic fluids. The results show that the velocity distribution, the pressure drop and the temperature are significantly affected by the magnetic field strength and the volumetric concentration of the ferrofluid particles. The flow in the axial direction is redistributed in four symmetric poles, where its maximum value is readily observed. A secondary flow is generated, due to the combined effect of the buoyancy, the curvature and the magnetic field, which improves the heat transfer between the walls and the fluid. The axial pressure gradient, which is required to maintain the same mass flow, also increases as the field strength and concentration of magnetic particles increases, but with a lower rate in comparison to the increase in heat transfer.