EFFECT OF TEMPERATURE DEPENDENT VISCOSITY ON THERMAL CONVECTION IN FERROFLUID LAYER

A linear stability analysis of onset of thermal convection in ferromagnetic fluid layer heated from below with temperature-dependent viscosity is investigated for general bounding surfaces. The eigenvalue problem is solved using a single term Galerkin technique and the values of critical Rayleigh numbers for different combinations of stress free and no-slip boundary conditions are computed for linear and exponential temperature dependent viscosity variations. The effects of temperature dependent viscosity parameter, magnetic Rayleigh number and the magnetization parameter on the onset of stationary convection are investigated numerically. It is found that increase in temperature dependent viscosity and decrease in magnetic number delay the onset of ferroconvection, while the nonlinearity of fluid magnetization has marginal influence on the stability of the system.