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DY: Fachverband Dynamik und Statistische Physik
DY 22: Invited Talk: Lucas Goehring (Nottingham)
DY 22.1: Invited Talk
Tuesday, March 23, 2021, 10:00–10:30, DYc
Stability and dynamics of convection in dry salt lakes — •Lucas Goehring1, Jana Lasser2, Marcel Ernst3, Matthew Threadgold4, Cédric Beaume4, and Steven Tobias4 — 1Nottingham Trent University — 2Complexity Science Hub Vienna — 3University of Kassel — 4University of Leeds
Dry lakes covered with a salt crust organised into beautifully patterned networks of narrow ridges are common in arid regions. This talk will consider the possible origins of this pattern as the surface expression of buoyancy-driven convection in the porous soil beneath a salt crust. Specifically, we look at convection in a deep porous medium with a constant through-flow boundary condition on a horizontal surface, which resembles the situation found below an evaporating salt lake. Solving the linear stability problem, we show that typical field conditions will be unstable to subsurface convection. Further exploring the non-linear regime of this model, we demonstrate how the growth of small downwelling plumes is itself unstable to coarsening, as the system develops into a dynamic steady state. Interestingly, a robust length-scale emerges for the pattern wavelength, which is largely independent of the driving parameters, and consistent with the size of typical salt crust patterns (arXiv:2004.10578). Finally, we will show how these results can be extended into three-dimensions and more realistic boundary conditions, and include comparisons to field observations.