2023/04/28 by Jiaxing Song, Olga Shishkina, Song, Jiaxing +3 · 2 citations
Biochemistry, Genetics and Molecular Biology · Engineering · Environmental Science · #Climate variability and models #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Turbulent Flows #Geomagnetism and Paleomagnetism Studies
paper · pdf · doi:10.48550/arxiv.2304.14854
openalex publication_date 2023/04/28 · openalex created_date 2023/05/02 · openalex updated_date 2026/07/28
The geostrophic turbulence in rapidly rotating thermal convection exhibits characteristics shared by many highly turbulent geophysical and astrophysical flows. In this regime, the convective length and velocity scales, heat flux, and kinetic and thermal dissipation rates are all diffusion-free, meaning that they are independent of the viscosity and thermal diffusivity. Our direct numerical simulations (DNS) of rotating Rayleigh--Bénard convection in domains with no-slip top and bottom and periodic lateral boundary conditions for a fluid with the Prandtl number Pr=1 and extreme buoyancy and rotation parameters (the Rayleigh number up to Ra=3×1013 and the Ekman number down to Ek=5×10-9) indeed demonstrate these diffusion-free scaling relations, in particular, that the dimensionless convective heat transport scales with the supercriticality parameter \widetildeRa≡ Ra Ek4/3 as Nu-1∝ \widetildeRa3/2, where Nu is the Nusselt number. We further derive and verify in the DNS that with the decreasing \widetildeRa the geostrophic turbulence regime undergoes a transition into another geostrophic regime where the convective heat transport scales as Nu-1∝ \widetildeRa3.