Developing laminar mixed convection of nanofluids in an inclined tube with uniform wall heat flux

Abstract

Purpose

The aim is to study the conjugate problem of developing laminar mixed convection flow and heat transfer of water‐Al₂O₃ nanofluid inside an inclined tube submitted to a uniform wall heat flux.

Design/methodology/approach

The set of non‐linear, coupled and fully elliptic governing equations has been solved using a “finite‐control‐volume” numerical method, the classical power‐law scheme for computing heat and momentum fluxes staggered and non uniform grids for spatial discretization of various regions of the tube.

Findings

Numerical results have shown that the presence of nanoparticles slightly intensifies the secondary flow due to buoyancy, in particular in the developing region. It also increases the average Nusselt number and decreases slightly the product ReC_f with respect to those of water. For the horizontal inclination, two new correlations have been proposed to calculate these two variables in the fully developed region, for Grashof number ranging from 10³ to 10⁵ and particle volume concentrations up to 7 per cent.

Practical implications

The results of this study can be employed for various practical heat transfer and thermal applications using nanofluids.

Originality/value

The present study constitutes an original contribution to the knowledge of nanofluid thermal behaviour.

Citation

Ben Mansour, R., Galanis, N. and Nguyen, C.T. (2009), "Developing laminar mixed convection of nanofluids in an inclined tube with uniform wall heat flux", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 19 No. 2, pp. 146-164. https://doi.org/10.1108/09615530910930946