Regensburg 2022 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 34: Fluid Physics: Turbulence and Convection
DY 34.2: Vortrag
Mittwoch, 7. September 2022, 15:45–16:00, H19
Transition between 2D and 3D rotating incompressible convection in direct numerical simulations — •Kevin Lüdemann and Andreas Tilgner — Institute of Astrophysics and Geophysics, Göttingen, Germany
Direct numerical simulations of an incompressible fluid with a Prandtl number of 0.7 are used to investigate differences between exact 2D and 3D convection. The fluid is rotating about a direction perpendicular to the direction of gravity (centrifugal gravity) and zonal flow is suppressed by horizontal walls in a container with an aspect ratio of 0.5. The convection is controlled by a Rayleigh number ranging from 104 to 109 and rotation is characterised by the Ekman number ranging from 10−1 down to 10−5. Due to the Taylor-Proudman theorem, the convective flow will be restrained to the plane perpendicular to the direction of rotation at high rotation rates. This behaviour will break down once convective driving and therefore kinetic energy is large enough. Thermal transport and kinetic energy density show different scalings for the 2D and 3D flow. The stability theory of a vortex with elliptical streamlines is tailored to the geometry in order to explain the transition. Ultimately, a dependence of the Reynolds number on the Rossby number is found Re ∝ Ro−2 for small Rossby numbers. Both are based on the RMS velocity of the vortex.