ABSTRACT

This paper reports the effect of Brownian motion on fluid flow and heat transfer performance using various nanofluids in natural convection in a square enclosure. The energy and Navier–Stokes equations are solved numerically using a finite-volume approach. The effect of Brownian motion was employed based on a thermal conductivity model with a Brownian motion effect. The effect of the volume concentration on the enhancement of heat transfer was studied incorporating the Brownian motion. The influence of the effective thermal conductivity on the enhancement was also investigated for a range of volume fraction concentrations. Various volume concentrations were tested in the present study: 2%, 3%, 4%, and 6%. Different Raleigh numbers were investigated for different nanoparticles. The results revealed that an increase in the volume fraction deteriorates the heat transfer. The velocity gradients were also found to be affected by the volume fraction. The temperature profile for different Rayleigh numbers is presented. Three different nanofluids (Cu–water, TiO–water, and AL₂O₃–water) were studied.