Numerical study of turbulent convection in inclined pipes with significant buoyancy influence

Convection heat transfer in inclined pipes with significant influence of buoyancy is investigated numerically. V2F eddy viscosity turbulence model is used and, to isolate the effect of buoyancy, constant values are used for thermo-physical properties with Boussinesq approximation for the density variation with temperature in the momentum equations. This problem is particularly significant for better understanding of flow and heat transfer in supercritical fluids. It is found that the same mechanism that leads to impairment of turbulence production, and thus heat transfer, in a vertical pipe (α = 90°) is present in inclined pipes; however it is less pronounced when α < 60°. Secondary flows are observed as a result of buoyancy force leading to non-uniformity of local heat transfer coefficient along the pipe periphery.