Natural double-diffusive convection for the Carreau shear-thinning fluid in a square cavity submitted to horizontal temperature and concentration gradients

Hydromagnetic double-diffusive convection of a binary gas mixture is simulated by a temperature-concentration latitce Bhatnagar-Gross-Krook (TCLBGK) model in a rectangular enclosure with the top and bottom walls being insulated, while linearly variable temperature or concentration gradient or both are imposed along the left and right walls from the bottom to the top and a uniform magnetic field is applied in x-direction. we take the Prandtl number =1, the Lewis =2, the thermal Raleigh number =105, the Hartmann number =0, 25, 50, the dimensionless heat generation or absorption =0, the aspect ration =2 for the enclosure and the ratio of buoyancy forces =0.8, 1.3. Numerical results are discussed in detail. It is founded that linearly variable temperature and concentration gradients have significant influence on the stratification and direction of streamlines and convection.

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Two-dimensional effects in double-diffusive convection

Journal of Fluid Mechanics ◽

10.1017/s0022112074001790 ◽

1974 ◽

Vol 63 (3) ◽

pp. 577-592 ◽

Cited By ~ 68

Author(s):

J. S. Turner ◽

C. F. Chen

Keyword(s):

Two Dimensional ◽

Double Diffusive Convection ◽

Mechanism Of Formation ◽

Concentration Gradients ◽

One Dimensional ◽

Horizontal Gradients ◽

Diffusive Convection ◽

Similar Density ◽

Double Diffusive ◽

Vertical Gradients

The limitations of existing one-dimensional experiments on double-diffusive convection are discussed, and a variety of new two-dimensional phenomena are described. We have used the sugar-salt system and shadowgraph photography to make exploratory studies of motions which can arise in a fluid with two smooth, opposing, vertical concentration gradients, with and without horizontal gradients. Many different effects have been observed, the most important of which are the following, (a) In the ‘finger’ case, local disturbances can propagate rapidly as wave motions, which cause a simultaneous breakdown to convection over large horizontal distances. (b) Layers formed in the’ diffusive’ sense overturn locally to produce fingers, but propagate more slowly, as convective rather than wave motions, (c) A series of layers, separated by diffusive interfaces, can become unstable, in the sense that successive layers merge in time as their densities become equal, (d) The presence of horizontally separated sources of water of similar density but differentT,Scharacteristics can lead to the development of strong vertical gradients and extensive quasi-horizontal layering.Most of our results are qualitative, but it is hoped that they will stimulate further quantitive work on each of the new processes described. It is already clear that much more needs to be done before the mechanism of formation of layers observed in the ocean can be regarded as properly understood.

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Hydromagnetic double-diffusive convection in a rectangular enclosure with opposing temperature and concentration gradients

International Journal of Heat and Mass Transfer ◽

10.1016/s0017-9310(01)00344-1 ◽

2002 ◽

Vol 45 (12) ◽

pp. 2465-2483 ◽

Cited By ~ 71

Author(s):

Ali J. Chamkha ◽

Hameed Al-Naser

Keyword(s):

Double Diffusive Convection ◽

Concentration Gradients ◽

Rectangular Enclosure ◽

Diffusive Convection ◽

Double Diffusive

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Marangoni Convection With a Deformable Surface

Journal of Applied Mechanics ◽

10.1115/1.2901514 ◽

1994 ◽

Vol 61 (3) ◽

pp. 681-688

Author(s):

F. McCaughan ◽

H. Bedir

Keyword(s):

Free Surface ◽

Marangoni Convection ◽

Interface Temperature ◽

Double Diffusive Convection ◽

Governing Equations ◽

Infinite Domain ◽

Concentration Gradients ◽

Diffusive Convection ◽

Bounded Below ◽

Double Diffusive

Double diffusive convection is considered in a semi-infinite domain, bounded below by a solid surface and above by a gas interface. Temperature and concentration gradients are imposed normal to the free surface and the linear stability of the fluid is examined. Traditional analyses are extended to include the effects of a deformable free surface. The governing equations are nondimensionalized and the parameter groupings are identified. We particularly focus on the effects of the capillary number, the Nusselt number and the Marangoni temperature and concentration numbers.

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