Ferrohydrodynamics Mixed Convection of a Ferrofluid in a Vertical Channel with Porous Blocks of Various Shapes

Abstract

Numerical simulations of (water-Fe3O4) ferrohydrodynamics (FHD) mixed convection inside a vertical channel are performed. The magnetic field is produced by three sources positioned outside the channel’s right wall. The latter is provided with localized heat sources surmounted by variously shaped porous blocks: rectangular, trapezoidal, and triangular. The general model of Darcy-Brinkman-Forchheimer is employed to describe the fluid flow in the porous regions, and the resulting equations are numerically solved by the finite volume approach. The influence of significant parameters, including the magnetic number (Mn), the Richardson number (Ri), and the shape of blocks, is examined. The results essentially reveal that the enhanced heat transfer brought by the magnetic field and its intensity increase is suppressed by the augmentation of Ri until a critical value, rising with Mn, beyond which the global Nusselt number increases again. The mean friction coefficient increases with increased Mn and reduced Ri. Compared to the case with no magnetic field, the maximum enhancement in heat transfer rate is around 132% for the rectangular blocks, 146% for the trapezoidal blocks, and 160% for the triangular blocks, while the maximum increase in pressure drop is approximately 45% for all the shapes. The triangular shape seems the most efficient because it leads to high heat transfer rates and low mean friction coefficients; its performance factor is 2.32 for a dominant magnetic field and 2.62 for a dominant buoyancy force. The current research's conclusions will help optimize the operation of various thermal engineering systems, including electronic devices, where the improved heat removal rate will keep the electronic components at a safe operating temperature.

Simulating the flow of interacting ferrofluids with multiparticle collision dynamics

“…Fluid dynamics simulation of ferrofluids have also been performed to investigate their use as displacing fluid in fractured porous media [15]. Other finite-element or finite-volume simulations have addressed some particular flow [16,17] and heat transfer [18] properties of ferrofluid flow through porous media. A porous medium approach was also used in finite-volume simulations of magnetic drug targeting of MNPs, coupling channel flow to adjacent tumor region via the permeable endothelium layer [19].…”