On features of ferrofluid convection caused by barometrical sedimentation

Abstract The experimental and numerical studies of Rayleigh convection in a thin cylindrical layer have been conducted for a ferrofluid containing magnetite particles suspended in kerosene carrier liquid. Near the onset of convection, the wave oscillatory convection was observed both in the experiments and in the numerical finite volume simulations. Time periods of temperature oscillations obtained using thermocouples were investigated using wavelet analysis. Thermosensitive liquid crystal sheet visualizations of flow patterns revealed irregular spatiotemporal behavior of convection, close to the threshold. Numerical simulations using a two-phase mixture model indicated that the initial sedimentation gradient may lead to spatiotemporally chaotic convection. Experimentally observed hysteresis and strong dependence of the measured heat flux from the prehistory of the experiments allude to non-Newtonian nature of ferrocolloids.