Laminar‐turbulent transition for low Reynolds number mixed convection in a uniformly heated vertical tube

2002 ◽  
Vol 12 (7) ◽  
pp. 839-854 ◽  
Author(s):  
A. Behzadmehr ◽  
N. Galanis ◽  
A. Laneville
Keyword(s):  
Reynolds Number ◽  
Mixed Convection ◽  
Low Reynolds Number ◽  
Vertical Tube ◽  
Turbulent Transition ◽  
Low Reynolds ◽  
Laminar Turbulent Transition

Performance of a variety of low Reynolds number turbulence models applied to mixed convection heat transfer to air flowing upwards in a vertical tube

2004 ◽  
Vol 218 (11) ◽  
pp. 1361-1372 ◽  
Author(s):  
W S Kim ◽  
J D Jackson ◽  
S He ◽  
J Li
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Mixed Convection ◽  
Low Reynolds Number ◽  
Convection Heat Transfer ◽  
Turbulence Models ◽  
Vertical Tube ◽  
Convection Heat ◽  
Mixed Convection Heat Transfer ◽  
Low Reynolds

The study reported here is concerned with mixed convection heat transfer to air flowing upwards in a vertical tube. Computational simulations of experiments from a recent investigation have been performed using an ‘in-house’ code which was written specifically for variable-property, developing, buoyancy-influenced flow and heat transfer in a vertical passage. The code incorporates a selection of two-equation, low Reynolds number turbulence models. The objective of the study was to evaluate the models in terms of their capability of reproducing the effects on turbulent heat transfer of non-uniformity of fluid properties and buoyancy. Direct comparisons have been made between results from the experimental investigation and those obtained by computational modelling for a range of conditions. The trends of impairment and enhancement of heat transfer owing to the influence of buoyancy found in the experiments were captured to some extent in the simulations using each of the models. However, none reproduced observed behaviour correctly over the entire range of buoyancy influence.

Analysis of transitional flow and heat transfer over turbine blades: Algebraic versus low-Reynolds-number turbulence model

2001 ◽  
Vol 215 (9) ◽  
pp. 1003-1018 ◽  
Author(s):  
S Sarkar
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Low Reynolds Number ◽  
Turbine Blades ◽  
Transitional Flow ◽  
Flow And Heat Transfer ◽  
Turbulent Transition ◽  
Wide Range ◽  
Low Reynolds ◽  
Laminar Turbulent Transition

The numerical simulation of flow and heat transfer over turbine blades involving laminar-turbulent transition is presented. The predicted results are compared with the experimental surface heat transfer and pressure distributions for two transonic turbine blades over a wide range of flow conditions. The time-dependent, mass-averaged Navier-Stokes equations are solved by an explicit four-stage Runge-Kutta scheme in the finite volume formulation. Local time stepping, variable-coefficient implicit residual smoothing and a full multigrid method have been implemented to accelerate the steady state calculation. The turbulence is simulated by the algebraic Baldwin-Lomax model together with an explicitly imposed model for transition. For comparison, the low-Reynolds-number version of the two-equation ( k-∊) model of Chien is also used. The modified Baldwin-Lomax model performs well in predicting the onset of laminar-turbulent transition, whereas the Chien model shows a tendency to mimic the transition early and over a shorter distance.

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