NUMERICAL STUDY ON NATURAL CONVECTION WITH NANOFLUIDS IN VERTICAL CHANNELS ASYMMETRICALLY HEATED

A numerical investigation on two-dimensional steady state natural convection with nanofluids in a vertical channel asymmetrically heated at uniform heat flux is carried out. The nanofluid is modeled using the both the single phase and mixture models also to compare the two models. The thermophysical properties are assumed constant with temperature the fluid flow is considered laminar and incompressible. The two-dimensional governing equations are numerically solved with finite volume method by means of the ANSYS-FLUENT code. The computational domain is made up of the principal channel and two lateral extended reservoirs at the open sections. The channel has the heated plate with the height L equal to 400 mm whereas the adiabatic plate has the height of the extended computational domain. The distance between the two vertical parallel plates, b, ranges between 10 mm and 40 mm. The two external reservoirs allow to simulate the external ambient and to assign at the boundary of the reservoirs a velocity equal to zero and the ambient temperature. Rayleigh number values are examined, from 10 to 1000. The main aim of the present study is to analyze the effect of channel spacing and the nanofluid mixture. Different values of assigned wall heat flux are considered. Results are presented in terms of velocity and temperature fields, and both temperature and velocity profiles at different significant sections are shown, to obtain a description of the natural convection inside the vertical channel. Finally, Average Nusselt number values are also evaluated.