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

Laminar mixed convection Al 2O 3 –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 Al 2O 3 –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. ► The nanofluid flow is simulated using the two phase mixture model. ► The Brownian motions and the dependence on temperature are considered. ► At a given Re, the nanofluids utilization in elliptic duct can enhances heat transfer. ► Using the elliptic pipes with AR = 0.75 have more advantages than the circular pipes. 5. The elliptic ducts with AR = 0.75 have the maximum Nusselt number.