TRANSPORT OF A HEATED HYDROPHOBIC SPHERICAL PARTICLE THROUGH POROUS MEDIUM

In this paper propulsion of a hydrophobic particle in a gel medium is analyzed numerically. Transport of nanoparticles in gel medium has relevance in the context of controlled drug delivery, colloid separation, and biotechnology. The gel medium is considered to be a homogeneous porous medium, and the hydrodynamics in the gel medium is governed by the Brinkman equation. A Navier-slip boundary condition on the surface of the particle is imposed. We have considered the hydrodynamics of microsized particles by considering the Reynolds number, based on the particle radius and translational velocity, as O(1). Subsequently, we have presented results for mixed convection of the heated hydrophobic particle for a moderate range of Reynolds number. Hydrophobicity of the particle creates a large reduction in drag compared to a hydrophilic particle. The variation of the drag factor, which measures the ratio of drag of a hydrophobic particle suspended in gel and clear fluid, with the gel permeability is found to be similar for any choice of the particle slip length. The flow separation from the surface of the hydrophobic particle delays with respect to Reynolds number. Heat transfer is relatively little influenced by the surface hydrophobicity of the particle.