| Abstract: |
| Fingering convection is a special case of buoyancy--driven convection that occurs when the most diffusing of two buoyancy--changing scalars is stratified in such a way as to stabilize the fluid, and the least diffusing scalar in the opposite direction, while the overall density decreases upward. In those cases, a well--understood linear instability of the motionless state produces convective motions dominated by small coherent structures, known as `salt fingers`, that travel vertically in the domains carrying most of the fluxes.
Once the convection is established, if the two Rayleigh numbers fall in a certain portion of the parameter space, a further instability occurs, which turns the horizontally averaged density field from a profile characterized by a constant gradient into a staircase--like profile that alternates regions of high and low density gradients.
This talk explores the possible explanations of the staircase--forming instability, examining in particular some simplified models that undergo a similar phenomenology. If time allows, the analogy between these models and some well-known techniques for non--linear image denoising will be illustrated. |
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