Numerical study of two phase laminar mixed convection nanofluid in elliptic ducts

Laminar mixed convection Al2O3-Water nanofluid flow in elliptic ducts with constant heat flux boundary condition has been simulated employing two phase mixture model. Three-dimensional Navier-Stokes, energy and volume fraction equations have been discretized using the finite volume method. The Brownian motions of nanoparticles have been considered to determine the thermal conductivity and dynamic viscosity of Al2O3-Water nanofluid, which depend on temperature. Simulation effects of solid volume fraction, aspect ratio and buoyancy forced on thermal and hydraulics behaviors of nanofluid flow in elliptic ducts have been presented and discussed. The calculated results show good agreement with the previous numerical data. Results show that in a given Reynolds number (Re) and Richardson number (Ri), increasing solid nanoparticles volume fraction increases the Nusselt number (Nu) while the skin friction factor decreases. Increasing aspect ratio (AR = b/a) in elliptic tubes reduces the local skin friction factor whereas it does not have any specified effect on the local Nusselt number. (C) 2011 Elsevier Ltd. All rights reserved.