Thermal Convection with and without Rotation
| Quand ? |
Le 11/09/2023, de 11:00 à 12:00 |
|---|---|
| Où ? | Salle Condorcet |
| Participants |
Robert Ecke |
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The fundamental forces of the electromagnetic, weak, and strong interactions are much more powerful than gravity but they are confined to small spatial and temporal scales and largely cancel out on the scales we observe and feel every day. On macroscopic length scales, gravity dominates as evidenced, for example, by the motions of planets or the very existence of the sun itself. With gravity comes the phenomena of buoyancy in which density differences can give rise to highly complex motions from the interior of the earth and the atmosphere on its surface to the life cycle of stars including their spectacular demise in a supernova. Thus, the motion of fluids owing to buoyancy in the presence of gravity is arguably the most important macroscopic physical process in the universe. Rotation is also ubiquitous in nature and is fundamental in understanding the motions of atmospheres and oceans on rotating planets and stars. I will describe the physics of convection, i.e., buoyancy-induced fluid flow deriving from thermal gradients. I will compare and contrast convection with and without convection including the unique aspects of velocity/vorticity Ekman boundary layers, the influence of lateral boundary currents in convective wall modes, and the exciting modes of convection under quasi-geostrophic constraint.