Numerical Study of Vertical Wall Jets: Influence of the Prandtl Number

This paper is a numerical investigation of a laminar isothermal plane two dimensional wall jet. Special attention has been paid to the effect of the inlet conditions at the nozzle exit on the hydrodynamic and thermal characteristics of the flow. The behaviour of various fluids evolving in both forced and mixed convection regimes near a vertical plate plane is carried out. The system of governing equations is solved with an implicit finite difference scheme. For numerical stability we use a staggered non uniform grid. The obtained results show that the effect of the Prandtl number is significant in the plume region in which the jet flow is governed by buoyant forces. Further for ascending X values, the buoyancy forces become dominating, and a certain agreement between the temperature profiles are observed, which shows that the velocity profile has no longer influence on the wall temperature evolution in this region. Fluids with low Prandtl number warm up more importantly, because for such fluids the effect of heat diffusion is higher.




References:
[1] Conférences C.E.A., E.D.F, Phènomènes thermiques et hydrauliques
non stationnaires, Jouy-en-Josas, Proc. Eyrolles Editeur, 1976.
[2] Nizou P.Y., Analogie entre transfert de chaleur et de quantité de
mouvement dans un jet pariètal plan turbulent, Int. J. Heat Mass Tran.
1984, Vol. 27, pp 1737-1748.
[3] Nizou P.Y., Tida T., Transfert de chaleur et de quantité de mouvement
dans les jets pariétaux plans turbulents, Int. J. Heat Mass Tran. 1995,
Vol. 38, pp 1187-1200.
[4] Leduc B., Joumotte A., Refroidissement d-une plaque plane par jet et
injection pariètaux, Revue générale de thermique. N┬░ 166, 1975, pp 692-
697.
[5] Lauder BE., Splanding DB, The numerical computation of turbulent
flow, Comput Methods appl Mech Eng. Vol. 3, 1974, pp 269-289.
[6] Ljuboja M., Rodi W., Calculation of turbulent wall jets with an algebric
Reynolds stress model, J. Fluid Eng.. Vol. 102, 1980, pp 350-356.
[7] Kechiche J., Mhiri H., Le Palec G., Bournot P., Etude numérique du
transfert de chaleur et de quantité de mouvement dans un jet pariètal
plan turbulent, P.c.n2004.
[8] Kechiche J., Mhiri H., Le Palec G., Bournot P., Numerical study of the
inlet conditions on a turbulent plane two-dimensional wall jets. Energy
conversion and management. Vol. 45, 2004, pp 2931-2949.
[9] Schlichting H., Boundary layer theory, 1979 , Mc Graw Hill.
[10] Gorla R.S., Combined natural and forced convection in a laminar wall
jet a long a vertical plates with uniform surface heat flux, Appl. Scient.
Res. Vol. 31, 1976, pp. 455-465
[11] Savage S.B., Chan G.K., The buoyant two dimensional laminar vertical
jets, Q.J. Mech. Appl. Math. 1970, Vol. 23, pp 413-430.
[12] Wilks G., Hunt R., The two dimensional laminar vertical jet with
positive or adverse buoyancy, Numerical heat tran. 1985, Vol. 8, pp 449-
468.
[13] Yu W.S., Lin H.T., Rigorous numerical solutions and correlations for
two dimensional laminar buoyant jets, Int. J. Heat Mass Tran. 1992, Vol.
35, pp 1131-1141.
[14] Mhiri H., Golli S., Le Palec G., Bournot P., Influence des conditions
d-émission sur un écoulement de type jet plan laminaire isotherme ou
chauffé, Revue générale de thermique. 1998, Vol. 37, pp 898-910.
[15] Marzouk S., Mhiri H., Le Palec G., Bournot P., Numerical study of
momentum and heat transfer in a pulsed laminar jet, Int. J. Heat Mass
Tran. 2003, Vol. 46, pp 4319-4334.
[16] Kechiche J., Application des modèles de turbulence ├á bas nombre de
Reynolds pour l-étude des jets pariétaux turbulents, Ph.D. thesis,
Université de la méditerrannée Aix MarseilleII, France - Université de
Monastir, Tunisie, 2006.
[17] Habli S., Mhiri H., Golli S., Le Palec G., Bournot P., Etude numérique
des conditions d-émission sur un écoulement de type jet axisymétrique
turbulent, Int. J. Therm. Sci. Vol. 40, 2001, pp 497-511.
[18] Mokni A., Kechiche J., Mhiri H., Le Palec G.,. Bournot P, Inlet
conditions influence on laminar plane wall jets, 3th international
Conference on diffusion in solids and liquids DSL2007, Portimao-
Portugal.