The fully developed laminar mixed convection flow in a vertical tube of constant surface temperature is investigated assuming that (i) the effect of viscous dissipation is significant, (ii) the Boussinesq approximation holds and (iii) the average flow velocity Um (as an experimentally accessible quantity) is prescribed. It is shown that under such conditions both upward (Um>0) and downward (Um<0) laminar flow solutions may exist. Whereas the downward flow solutions exist for any prescribed Um<0, upward flows only exist below a maximum value Um,max of Um. Moreover, a nontrivial flow configuration is possible also for Um=0. A remarkable feature of the problem is that for Um

Uni- and bidirectional mixed convection flow regimes described by dual solutions in a vertical duct

BARLETTA, ANTONIO;LAZZARI, STEFANO;
2007

Abstract

The fully developed laminar mixed convection flow in a vertical tube of constant surface temperature is investigated assuming that (i) the effect of viscous dissipation is significant, (ii) the Boussinesq approximation holds and (iii) the average flow velocity Um (as an experimentally accessible quantity) is prescribed. It is shown that under such conditions both upward (Um>0) and downward (Um<0) laminar flow solutions may exist. Whereas the downward flow solutions exist for any prescribed Um<0, upward flows only exist below a maximum value Um,max of Um. Moreover, a nontrivial flow configuration is possible also for Um=0. A remarkable feature of the problem is that for Um
A. Barletta; S. Lazzari; E. Magyari
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/50571
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