عنوان مقاله [English]
This article reports a numerical study of fluid flow and heat transfer of mixed convection in a shallow cavity with different aspect ratios subjected to a nanofluid with Temperature-dependent dynamic viscosity and thermal conductivity. The side walls of shallow cavity are assumed adiabatic whereas top and bottom walls are kept at low(Tc) and high(Th) temperatures, respectively. Using a developed FORTRAN code, equations of continuity, momentum and energy are solved with associated with boundary condition by a finite volume method (FVM), numerically. The new models proposed by Xue and Jang are used to calculate the thermal conductivity and dynamic viscosity of nanofluid, respectively. The influence of changes in lids velocity ratios aspect ratio, Richardson number and existence of nanoparticles on hydrodynamic and thermal characteristics have been investigated. Water and water/Al2O3 nanofluid with particle diameter of 80 nanometers, diameter ratio of 0.006 and T=298(K) have been used as working fluids. Results show that in a constant parametric range, heat transfer in a shallow cavity with Length twice the height (A.R=2) is more than compared to other cases. Also the existence of nanoparticles increases the heat transfer inside the cavity.