scholarly journals Modeling of the Surface Convective Layer of Salt-Gradient Solar Ponds

1982 ◽  
Vol 104 (4) ◽  
pp. 293-298 ◽  
Author(s):  
Y. S. Cha ◽  
W. T. Sha ◽  
W. W. Schertz
Keyword(s):  
Double Diffusive Convection ◽  
Vertical Temperature ◽  
Solar Ponds ◽  
One Dimensional ◽  
Diffusive Convection ◽  
Combined Action ◽  
Salt Gradient ◽  
Wind Mixing ◽  
Convective Layer ◽  
Double Diffusive

A one-dimensional numerical model is developed to predict the diurnal variations of vertical temperature and concentration profiles in salt-gradient solar ponds. The model employs augmented thermal and mass diffusivities due to turbulent wind mixing and double-diffusive convection. Numerical results indicate that the thickness of the surface convective layer increases with wind speed (or the wavelength of the surface wave). Double-diffusive convection is, in the absence of wind, capable of sustaining a mixed layer at the surface when strong cooling occurs over the pond. In field ponds, the surface convective layer is probably maintained as a result of the combined action of wind-generated turbulent mixing and double-diffusive convection.

scholarly journals Reply

2008 ◽  
Vol 65 (3) ◽  
pp. 1095-1097 ◽  
Author(s):  
David M. Schultz ◽  
Adam J. Durant ◽  
Jerry M. Straka ◽  
Timothy J. Garrett
Keyword(s):  
Volcanic Ash ◽  
Effective Means ◽  
Double Diffusive Convection ◽  
Vertical Temperature ◽  
Effective Mechanism ◽  
Gravitational Forces ◽  
Salt Fingers ◽  
Diffusive Convection ◽  
Double Diffusive

Abstract Doswell has proposed a mechanism for mammatus called double-diffusive convection, the mechanism responsible for salt fingers in the ocean. The physics of salt fingers and mammatus are different. Unlike the ocean where the diffusivity is related to molecular motions within solution, the hydrometeors in clouds are affected by inertial and gravitational forces. Doswell misinterprets the vertical temperature profiles through mammatus and fails to understand the role of settling in volcanic ash clouds. Furthermore, given that mixing is a much more effective means of transferring heat in the atmosphere and given idealized numerical model simulations of mammatus showing that the destabilizing effect of subcloud sublimation is an effective mechanism for mammatus, this reply argues that double-diffusive convection is unlikely to explain mammatus, either in cumulonimbus anvils or in volcanic ash clouds.

Two-dimensional effects in double-diffusive convection

1974 ◽  
Vol 63 (3) ◽  
pp. 577-592 ◽  
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.

The Onset of Double-Diffusive Convection in a Vertical Cylinder With Vertical Throughflow

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
D. A. Nield ◽  
A. V. Kuznetsov
Keyword(s):  
Vertical Cylinder ◽  
Double Diffusion ◽  
Linear Stability Theory ◽  
Double Diffusive Convection ◽  
Vertical Temperature Gradient ◽  
Vertical Temperature ◽  
Onset Of Convection ◽  
Diffusive Convection ◽  
Vertical Throughflow ◽  
Double Diffusive

The effect of vertical throughflow on the onset of convection, induced by an applied vertical temperature gradient in a vertical cylinder is studied analytically using linear stability theory. This problem is important to hydrologists to investigate under what conditions convection is taking place in a well or borehole. The effect of double diffusion is included. Both nonoscillatory and oscillatory situations are studied.

DOUBLE-DIFFUSIVE CONVECTION IN LIQUID FREON

1998 ◽  
Author(s):  
Pierre Dupont ◽  
O. Gorieu ◽  
Hassan Peerhossaini ◽  
M. Kestoras
Keyword(s):  
Double Diffusive Convection ◽  
Diffusive Convection ◽  
Double Diffusive
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