Simulating zonation in geophysical flows by laboratory experiments

The entrainment assumption, relating the inflow velocity to the local mean velocity of a turbulent flow, has been used successfully to describe natural phenomena over a wide range of scales. Its first application was to plumes rising in stably stratified surroundings, and it has been extended to inclined plumes (gravity currents) and related problems by adding the effect of buoyancy forces, which inhibit mixing across a density interface. More recently, the influence of viscosity differences between a turbulent flow and its surroundings has been studied. This paper surveys the background theory and the laboratory experiments that have been used to understand and quantify each of these phenomena, and discusses their applications in the atmosphere, the ocean and various geological contexts.

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Using data assimilation in laboratory experiments of geophysical flows

Journal of Marine Systems ◽

10.1016/j.jmarsys.2006.01.016 ◽

2007 ◽

Vol 65 (1-4) ◽

pp. 532-539 ◽

Cited By ~ 1

Author(s):

M. Galmiche ◽

J. Sommeria ◽

P. Brasseur ◽

J. Verron

Keyword(s):

Data Assimilation ◽

Laboratory Experiments ◽

Geophysical Flows ◽

Using Data

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The difference between monopole vortices in planetary flows and laboratory experiments

Journal of Fluid Mechanics ◽

10.1017/s0022112093002253 ◽

1993 ◽

Vol 254 ◽

pp. 561-577 ◽

Cited By ~ 9

Author(s):

J. Nycander

Keyword(s):

Laboratory Experiments ◽

Rossby Waves ◽

Integral Relation ◽

Geophysical Flows ◽

Rossby Number ◽

Centre Of Mass ◽

Velocity Difference ◽

General Integral ◽

Nonlinear Contribution ◽

The Difference

This work is an attempt to explain observations of vortices in experiments with shallow water in rotating paraboloidal vessels. The most long-lived vortices are invariably anticyclones, while cyclones quickly disperse, and they are larger than the Rossby radius. These experiments are designed to simulate geophysical flows, where large, long-lived, anticyclonic vortices are common.The general condition for vortices to be steady is that they propagate faster than linear Rossby waves, so that the vortex energy is not dispersed by coupling to linear waves. The propagation velocity is determined by a general integral relation that gives the velocity of the centre of mass. In geophysical flows, to lowest order in the Rossby number, the difference between the centre-of-mass velocity and the maximum phase velocity of the Rossby waves is proportional to the relative perturbation of the fluid depth. Since for anticyclones the difference is positive they may be steady, whereas cyclones cannot be.In the laboratory experiments this velocity difference is absent because of the latitudinal dependence of the effective gravity caused by the centrifugal force. However, to the next order in the Rossby number, there is another nonlinear contribution, so that anticyclones (but not cyclones) still propagate faster than the linear Rossby waves, and may thus be steady. The velocity difference is smaller than for geophysical flows, and vanishes in the limit of small Rossby number. The existence conditions also show that we can expect the experimental vortices to be smaller (as measured by the Rossby radius) than the planetary vortices. The theory does not apply to vortices that are much smaller than the Rossby radius.

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Covering of cometary nucleus by refractory crust and its evolution into asteroid-like body

International Astronomical Union Colloquium ◽

10.1017/s0252921100031675 ◽

1999 ◽

Vol 173 ◽

pp. 365-370

Author(s):

Kh.I. Ibadinov

Keyword(s):

Laboratory Experiments ◽

Cometary Nucleus ◽

Sublimation Rate ◽

Cometary Nuclei ◽

Short Period Comet ◽

Short Period ◽

Brightness Decrease ◽

Crust Thickness ◽

Ice Sublimation ◽

Period Comet

AbstractFrom the established dependence of the brightness decrease of a short-period comet dependence on the perihelion distance of its orbit it follows that part of the surface of these cometary nuclei gradually covers by a refractory crust. The results of cometary nucleus simulation show that at constant insolation energy the crust thickness is proportional to the square root of the insolation time and the ice sublimation rate is inversely proportional to the crust thickness. From laboratory experiments resulted the thermal regime, the gas productivity of the nucleus, covering of the nucleus by the crust, and the tempo of evolution of a short-period comet into the asteroid-like body studied.

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When Does Voice Have to be More Than Only Listening? Procedural Justice Effects as a Function of Confident Leadership

Journal of Personnel Psychology ◽

10.1027/1866-5888/a000011 ◽

2010 ◽

Vol 9 (2) ◽

pp. 69-78 ◽

Cited By ~ 8

Author(s):

David De Cremer ◽

Maarten Wubben

Keyword(s):

Procedural Justice ◽

Interaction Effect ◽

Laboratory Experiments ◽

Negative Emotions

The present research examined how voice procedures and leader confidence affect participants’ negative emotions and willingness to withdraw. It was predicted that receiving voice would be valued out of instrumental concerns, but only when the enacting leader was high in confidence. Two laboratory experiments indeed showed an interaction between type of voice (pre-decisional vs. post-decisional) and leader’s confidence (low vs. high) on participants’ negative emotions and willingness to withdraw. In particular, post-decision voice only led to more negative responses than did pre-decision voice when the enacting leader was high in confidence. Negative emotions mediated this interaction effect of type of voice on willingness to withdraw. Implications for integrating the leadership and procedural justice literatures are discussed.

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