Heat generating porous matrix effects on Brownian motion of nanofluid

Abstract

Purpose

The purpose of this study is to indicate the effect of mounting heat generating porous matrix in a close cavity on the Brownian term of CuO-water nanofluid and its impact on improving the Nusselt number.

Design/methodology/approach

Because of the presence of heat source in porous matrix, couple of energy equations is solved for porous matrix and nanofluid separately. Thermal conductivity and viscosity of nanofluid were assumed to be consisting of a static component and a Brownian component that were functions of volume fraction of the nanofluid and temperature. To explain the effect of the Brownian term on the flow and heat fields, different parameters such as heat conduction ratio, interstitial heat transfer coefficient, Rayleigh number, concentration of nanoparticles and porous material porosity were investigated and compared to those of the non-Brownian solution.

Findings

The Brownian term caused the cooling of porous matrix because of rising thermal conductivity. Mounting the porous material into cavity changes the temperature distribution and increases Brownian term effect and heat transfer functionality of the nanofluid. Besides, the effect of the Brownian term was seen to be greatest at low Rayleigh number, low-porosity and small thermal conductivity of the porous matrix. It is noteworthy that because of decrement of thermal conduction in high porosities, the impact of Brownian term drops severely making it possible to obtain reliable results even in the case of neglecting Brownian term in these porosities.

Originality/value

The effect of mounting the porous matrix with internal heat generation was investigated on the improvement of variable properties of nanofluid.

Citation

Zehforoosh, A., Hossainpour, S. and Rashidi, M.M. (2019), "Heat generating porous matrix effects on Brownian motion of nanofluid", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 29 No. 5, pp. 1724-1740. https://doi.org/10.1108/HFF-02-2018-0068