Ferro-liquid droplet heat transfer on water surface: Effect of droplet volume on droplet fluidity

Heat transfer analysis of a transformer oil–based, a sessile ferro-liquid droplet formed on a stagnant water surface is carried out. Two counterrotating circulation cells are formed inside water and the droplet. Increasing the droplet volume enhances the maximum velocity and circulation cell sizes inside the droplet. The convection current and heat diffusion from the droplet bottom toward the droplet tip enhances temperature increase in the central region of the droplet. The Bond number remains greater than unity for all droplet volumes, indicating the significant contribution of the buoyancy current to the flow field. The Nusselt number increases with increasing droplet volume.