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Geophysical and astrophysical turbulence to the extreme
报告题目:Geophysical and astrophysical turbulence to the extreme
报 告  人:Xiaojue Zhu (Max Planck Institute for Solar System Research, Germany)
报告时间:2024-03-21 14:00:00
报告地点:Hall 212, Astronomy Building
Abstract: Rotational convection and magneto-convection serve as exemplary models for numerous geophysical and astrophysical fluid dynamics phenomena. In the context of rapidly rotating convection within the geostrophic regime, various critical attributes such as convective length and velocity scales, heat flux, as well as kinetic and thermal dissipation rates, exhibit a distinctive feature - they remain unaffected by diffusion. This signifies that these attributes remain independent of the viscosity and thermal diffusivity of the fluid. Our direct numerical simulations (DNS) of rotating Rayleigh–Bénard convection, conducted in domains with no-slip conditions at the top and bottom boundaries, indeed demonstrate these diffusion-free scaling relations. We further derive and verify in the DNS that with the decreasing Rayleigh number the geostrophic turbulence regime undergoes a transition into another geostrophic regime where the heat transport enjoys a much steeper scaling exponent. For magnetoconvection, using the same framework from rotating convection, we show that suprisingly the diffusion-free heat transport scaling can be realized even when the flow field is not really turbulent.

Bio:
Dr. Xiaojue Zhu (朱晓珏) is currently an independent Max Planck Research Group Leader at the Max Planck Institute for Solar System Research in Goettingen, Germany. His group's major research fields are geophysical and astrophysical turbulence and the associate numerical techniques. He obtained his PhD from the Physics of Fluids Group at the university of Twente in the Netherlands in 2018. After that, he was a postdoc researcher at Harvard University for 2 years. He has published 38 papers in refereed scientific journals, including Nature Physics, Reports on Progress in Physics (invited review), PNAS, Physical Review Letters, Astrophysical Journal Letters, Journal of Fluid Mechanics.