In this paper, the linear stability analysis of the thermal convection of a nanofluid layer heated from below with temperature-dependent viscosity for general boundary conditions is carried out. The principle of exchange of stabilities is shown to be valid for the problem, which means that instability sets in as stationary convection. The expressions for Rayleigh numbers with variable viscosities for each combination of rigid and dynamically free boundary conditions are derived using the Galerkin method. The values of critical wave numbers for different values of viscosity parameters, and consequently the critical Rayleigh numbers at which the onset of convection starts, are computed numerically. The effects of various parameters (namely, the viscosity variation parameter, Lewis number, and concentration Rayleigh number on the onset of stationary convection for each case of boundary combination) are computed numerically and depicted graphically. From the obtained results, it was found that the induction of nanoparticles in the convective motions of fluids increases the heat flow rate, and consequently hasten the convective motion. Since the heat flow rate is considered to be the key parameter for the performances of many devices (including spacecraft active thermal control systems), therefore the heat flow rate consequently, the performance of such devices can be enhanced by the use of nanofluids as a coolants, fuel additives, or lubricants.
Effect of Temperature Dependent Viscosity on Thermal Convection of Nanofluids: Steady Case
Journal of Thermophysics and Heat Transfer ; 29 , 1 ; 90-101
2014-09-19
12 pages
Article (Journal)
Electronic Resource
English
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