Conditions for pressure build-up due to buoyancy effects on forced convection in vertical eccentric annuli under thermal boundary condition of first kind

This paper presents a numerical investigation for the conditions at which the buoyancy effects (represented by the buoyancy parameter (Gr/Re)) result in pressure build-up due to mixed convection in vertical eccentric annuli under thermal boundary conditions of first kind. In this regard, the critical values of buoyancy parameter (Gr/Re)crt at which the pressure gradient vanishes and starts to become positive leading to the pressure build-up are obtained numerically for radius ratio N=0.5 and eccentricity E=0.1–0.7. Results of practical applications such as the locations at which the negative pressure gradient becomes zero changing its sign to be positive, the locations of zero pressure defect and the fully developed length under different operating conditions are drawn and presented. For sufficiently large values of Gr/Re≫(Gr/Re)crt, possibilities and locations of flow reversal incipient are determined. Information of technical relevance is presented.