Natural convection of high Prandtl number fluids with variable viscosity in a vertical slot

1996 ◽  
Vol 39 (13) ◽  
pp. 2663-2670 ◽  
Author(s):  
Y.Y. Jin ◽  
C.F. Chen
Keyword(s):  
Natural Convection ◽  
Prandtl Number ◽  
Variable Viscosity ◽  
Vertical Slot ◽  
High Prandtl Number

Formation of cells in natural convection in a vertical slot at large Prandtl number

1996 ◽  
Vol 314 ◽  
pp. 299-314 ◽  
Author(s):  
Shunichi Wakitani
Keyword(s):  
Natural Convection ◽  
Prandtl Number ◽  
Variable Viscosity ◽  
Numerical Results ◽  
Unsteady State ◽  
Supercritical Conditions ◽  
Bifurcation Phenomena ◽  
Vertical Slot

This paper presents several features at supercritical conditions of natural convection of large Prandtl number fluids in a vertical slot. Both experimental and numerical results show that even at slightly supercritical conditions the multicellular flow is in an unsteady state which is attributed to the moving and merging of cells. The effect of variable viscosity on the unsteadiness is investigated numerically. Successive merging and appearance of cells is characteristic of this convection so that the number of secondary cells changes with time. The bifurcation phenomena characterized by several modes of unsteady cellular flow are examined.

Instability of Convection and Heat Transfer of High Prandtl Number Fluids in a Vertical Slot

1996 ◽  
Vol 118 (2) ◽  
pp. 359-365 ◽  
Author(s):  
Y. Y. Jin ◽  
C. F. Chen
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Critical Rayleigh Number ◽  
Convective Motion ◽  
Flow Patterns ◽  
Convection And Heat Transfer ◽  
Number Range ◽  
Vertical Slot ◽  
High Prandtl Number ◽  
Good Agreement

The stability of convective motion of high-Prandtl-number fluids, generated by a lateral temperature difference across a vertical slot with aspect ratio 15, is studied numerically. The Prandtl number range studied is from 50 to 2000. The nonlinear governing equations are solved by a finite difference method. The predicted flow patterns and critical values are in good agreement with the recent experimental results of Wakitani (1994). It is found that the vorticity distribution along the vertical centerline of the slot is a very sensitive indicator of the onset of multicellular flow. The critical Grashof number varies almost inversely with the Prandtl number; consequently, the critical Rayleigh number is essentially independent of the Prandtl number. Heat transfer results show good agreement with the experimentally correlated values, and they are independent of the Prandtl numbers and the flow patterns.

A note on natural convection in a vertical slot

1975 ◽  
Vol 72 (1) ◽  
pp. 87-93 ◽  
Author(s):  
G. de Vahl Davis ◽  
G. D. Mallinson
Keyword(s):  
Experimental Study ◽  
Natural Convection ◽  
Prandtl Number ◽  
Numerical Solution ◽  
Boussinesq Equations ◽  
Aspect Ratios ◽  
Vertical Slot ◽  
Rayleigh Numbers ◽  
Vertical Cavity

The secondary and tertiary motions which were observed by Elder (1965) during his experimental study of natural convection in a vertical cavity have been obtained in a numerical solution of the Boussinesq equations. Aspect ratios up to 20, Rayleigh numbers up to 3000000, a Prandtl number of 1000, and up to almost 11000 effective mesh points were used.

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