Numerical study of flow and free convection of water/silver nanofluid in a circular cavity influenced by hot fluid flow

Abstract

In this numerical study, the numerical simulation of laminar free convection of water/silver nanofluid in a circular cavity under the effect of hot water fluid outside the cavity is carried out. The cooling fluid is water silver nanofluid at a volume concentration of φ = 0–0.06. This study was done for Gr = 102, 103 and 104 using the finite volume method. The Reynolds numbers of Re = 1, 10 and 100 were used. The results of the study show that due to the temperature difference between the cavity and the entering fluid, heat transfer occurs between the hot fluid in the channel and the nanofluid in the cavity at the start of the channel. This temperature difference between the surface and the fluid reinforces the buoyancy force and the Grashof number, intensifying the cavity flow and creating a more uniform cavity temperature distribution. For low Gr number, higher φ results in modest temperature gradient reduction. Using a higher fluid flow, the channel-cavity heat transfer increases which elevate dimensionless temperature curves. At a higher φ, due to the higher fluid viscosity and density, a higher momentum is required for flow convection and circulation. As a result, a stronger buoyancy force aids with free convection intensity, which is effective in elevating the Nusselt number curve values. By increasing the Reynolds number, a higher cavity heat transfer occurs due to the stronger circulating fluid's momentum.