In the present attempt, the effect of single and multiphase models on flow behaviour and thermal convection of a kerosene based ferrofluid in a cylindrical geometry is investigated. Constant temperatures on the top and bottom ends and adiabatic boundary conditions on sidewalls were applied. The domain heated from below and subjected to a uniform magnetic field parallel to temperature gradient. It was found at high solid volume fraction mixture method is more effective than single phase approach. To study the aggregation and particles diameters' effects on hydrodynamics of the system just mixture model can be applied. Using this model it was obtained that with higher magnetic particles' diameter heat transfer will decrease, and Rayleigh rolls will not be observed.