Investigation of Brownian Motion of CuO-Water Nanofluid in a Porous Cavity with Internal Heat Generation by Using of LTNE Model

In this paper, the effect of the Brownian term in natural convection of CuO-Water nanofluid inside a partially filled porous cavity, with internal heat generation has been studied. It is assumed that the viscosity and thermal conductivity of nanofluid consists of a static part and a Brownian part of which is a function of temperature and the volume fraction of nanofluid. Because of internal heat generation, the two-equation model is used to separately account for the local solid matrix and nanofluid temperatures. To study the effect of Brownian term various parameters such as the Rayleigh number, volume fraction of nanofluid, porosity of the porous matrix, and conductivity ratio of porous media is examined and the flow and heat fields are compared to the results of non-Brownian solution. The results show that Brownian term reduces nanofluid velocity and make smoother streamlines and increasing the thermal conductivity leads to cooling of porous material and achieving more Nusselt. Also the greatest impact of Brownian term is in low-porosity, low Rayleigh or small thermal conductivity of the porous matrix. In addition, mounting the porous material increases the Brownian effect and heat transfer performance of nanofluid but increasing porosity up to 0.8 reduces this effect.