Effects of Inclination Angle on Laminar Mixed Convection of a Nanofluid Flowing through an Annulus

Numerical study was done to investigate the effect of inclination angle on the hydrodynamics and thermal parameters of a nanofluid laminar flow throughout an annulus. For Al2O3/water nanofluid, profiles of axial velocity, contours of temperature, and secondary flows at the annulus cross sections are presented and discussed at different inclination angles. The results confirm that the axial component of buoyancy forces and secondary flows influences the flow regime. While the axial variation of friction coefficient was affected by the secondary flows for Ri = 0.1, it continuously changes with axial component of buoyancy forces as a function of inclination angle for Ri = 3. The results indicate that the maximum value of heat transfer coefficient obtained at the horizontal condition where the buoyancy forces result the strongest secondary flow.