The Sensitivity of Rotating Rayleigh-Bénard Convection to Ekman Pumping


Rapidly rotating convection is relevant in many geophysical and astrophysical settings, including planetary interiors, oceans and atmospheres. To study these systems, the canonical paradigm of rotating Rayleigh-Bénard convection, or the flow between two rotating parallel plates heated from below, is investigated using three methods: asymptotic methods, DNS and laboratory experiments. While simulations have seen good agreement in results for stress free boundary conditions, the case of no-slip boundaries presents an interesting difference. Along these boundaries, Ekman layers form and Ekman pumping occurs. Recent results have shown that Ekman pumping has a nontrivial effect on the flow even at low Ekman number. However, at present, DNS and laboratory experiments cannot probe the regime of asymptotically small Ekman numbers. Using a combination of results from DNS and the asymptotic model, we form the 2D surface of the heat transfer as a function of the Rayleigh number and the Ekman number for no-slip boundaries. This surface covers a range of data only accessible through the use of the asymptotically reduced model. These results provide insight into the sensitivity of the flow to Ekman pumping and allow for an empirical determination of the heat transfer enhancement due to no-slip boundaries at low Ekman, a regime of interest for modeling planetary interiors. The results also serve as a foundation for the next generation of laboratory experiments.

Feb 28, 2017 3:30 PM — 4:30 PM
Bechtel Collaboratory, Discovery Learning Center
Engineering Center, University of Colorado at Boulder, Boulder, CO 80309

University of Colorado Boulder