"Dust devils" in convection
Just figures and animations from recent simulations of convection in a box.

Last modified Monday, 01-Sep-2008 17:04:35 CDT
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Here is a brief look at the formation of "dust devils" in idealized thermal convection between free-slip parallel plates. (This investigation was inspired by the research of Dr. Katharine Kanak). The dimensionless diffusivity is 0.01. The Rayleigh number is 8192 times the critical Rayleigh number. The layer is heated only from below. A model with dimensions 4x4x1 and gridpoints 128x128x32 was run from t=0 to t=32. There is no vertical vorticity initially, and all vertical vorticity arises from the tilting of baroclinically-generated horizontal vorticity.

To learn more, you may want to obtain our online article published in Atmosperic Science Letters.

In the animations of the experiment where only the bottom is heated, a strong cyclonic "dust devil" forms near the south boundary at t=24. The above is a vis5d rendering showing a green cone of low pressure (isosurface -1.63) yellow temperature (isosurface 6.59) and purple vertical velocity (isosurface 1.3). There is at least the appearance of the updraft partially wrapping the low pressure. This is expected to occur as the vortex reaches the thermodynamic speed limit, and the core becomes hydrostatically balanced.

The above shows vorticity (isosurface=15) and w.

there should be images here