Numerical investigation of the heat transfer enhancement using various viscosity models in chamber filled with water–CuO nanofluid

Abstract

Heat transfer enhancement in two-dimensional lid-driven chamber, filled with water–cupric oxide nanofluid is investigated numerically. Different viscosity models are used to evaluate heat transfer enhancement and the increase in the average Nusselt number on hot wall. The horizontal boundaries of the square domain are assumed to be insulated, and the vertical ones are considered to be isothermal. The model of Chon et al. is exerted for heat conduction coefficient. The standpoint of each viscosity model fundamentally varies in terms of whether it takes different variables such as temperature effects, Brownian motion of the nanoparticles, the radii of aggregated particles, and the volume fraction of nanoparticles into account. The governing stream-vorticity equations are solved using a second-order central finite difference scheme, coupled to the conservation of mass and energy. The main sensitive parameters of interest to investigate the viscosity models are chosen as volume fraction of the nanoparticles φ, and Richardson number Ri. The performance study of the viscosity models and the interpretation of the corresponding results of streamlines, isothermal lines, and velocity components are done in a different range of φ and Ri for forced, mixed and natural convections. It is found that higher heat transfer is predicted when Brownian motion and temperature effects are considered.