Numerical Simulation of Maximum Spreading of an Impacting Ferrofluid Droplet under a Vertical Magnetic Field.

Theoretical modeling is proposed to predict the maximum spreading of water-based ferrofluid droplets impacting upon dry surfaces influenced by a vertical magnetic field. Constructed on the principle of energy balance, this model demonstrates excellent agreement with numerical findings across various impact velocities, contact angles, and magnetic strengths. Notably, as magnetic field strength escalates, magnetic forces prevail over viscous and capillary forces, exerting a significant influence on spreading dynamics and diminishing the maximum spreading diameter of ferrofluid droplets if the impacting shape is spherical.

The linear stability of Hunt-Rayleigh-Bénard flow.

The stability of a pressure driven flow in a duct heated from below and subjected to a vertical magnetic field (Hunt-Rayleigh-Bénard flow) is studied. We use the Chebyshev collocation approach to solve the eigenvalue problem for the small-amplitude perturbations. It is demonstrated that the magnetic field can stabilize the flow, while the temperature field can disturb the flow.