Magnetic action on convection and heat transfer in ferrofluid

Abstract

The interplay of buoyancy and thermo-magnetic convection mechanisms are investigated in a horizontal ferrofluid layer heated from one wide side and cooled from another in the presence of external uniform transversal magnetic field. The influence of gravitational settling of magnetic particles and their aggregates on heat transfer and convection instability is also considered. The ferro-colloids with different concentrations of magnetic phase are employed for the control of driving magnetic forces. It is shown that in concentrated colloid the driving forces prevail over suppress ones, but in weak concentrated colloid the gradients of density due to gravity sedimentation of particles overwhelm convection stirring. It is important that thermo-magnetic convection mechanism allows strengthening of heat transfer in ferrofluid three times.