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ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
Numerical investigation of ferrofluid droplets motion in pressure driven flows
Submission Author:
Rogério De Paula , DF , Brazil
Co-Authors:
Rogério De Paula, Taygoara Oliveira
Presenter: Rogério De Paula
doi://10.26678/ABCM.ENCIT2022.CIT22-0466
Abstract
In this work, the motion of ferrofluid droplets dispersed in a pressure-driven flow under the influence of an external magnetic field is studied using numerical methods. The model assumes droplets of superparamagnetic fluids dispersed in a non-magnetizable Newtonian media between two parallel plates in incompressible laminar pressure-driven flow, affected by an external uniform magnetic field. We solve the incompressible Navier-Stokes equations, with additional source terms representing the pressure jump due to the surface tension and the magnetic forces inside the droplet, couplet to a Laplace equation for the magnetic potential. The numerical methodology uses the Level Set method to track the droplet surface and the projection method for the pressure-velocity coupling. The MAC second-order finite differences scheme is used for spatial discretization and the Crank-Nicholson method is applied to the temporal evolution of the momentum equation. High order ENO and WENO conservative schemes are used for the solution of the Level Set equations. Inertia effects are minimized by keeping a low Reynolds number. In this limit, the main parameters of the problem are the capillary number (Ca), accounting for the ratio between the shear stress and the surface tension; and the magnetic capillary number (Ca_mag), which is the external magnetic field intensity normalized using the surface tension. We present a numerical study on the influence of the external magnetic field on the drift velocity of the droplets. It is observed that droplets placed near the wall tend to migrate towards the center, showing that droplets migrate to regions with less intense shear rates and migrates faster with larger deformation in the presence of a magnetic field.
Keywords
Pressure Driven, ferrofluid, Numerical analysis, Emulsion
