# BPCPPDYSOE21 – wissenschaftliches Programm

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# DY: Fachverband Dynamik und Statistische Physik

## DY 2: Fluid Physics 1 - organized by Stephan Weiss and Michael Wilczek (Göttingen)

### DY 2.3: Vortrag

### Montag, 22. März 2021, 09:40–10:00, DYa

**Generation of zonal flows in convective systems by travelling thermal waves** — •Philipp Reiter^{1}, Rodion Stepanov^{2}, and Olga Shishkina^{1} — ^{1}Max Planck Institute for Dynamics and Self-Organization, Götttingen, DE — ^{2}Institute of Continuous Media Mechanics, Russian Academy of Science, Perm, RU

In this work we study the effects of travelling thermal waves which are applied at the fluid layer, specifically on the formation of global mean horizontal (zonal) flow. Earlier studies suggest that the periodic heating of the Earth's, due to Earth's rotation, could cause zonal winds in the atmosphere. Additionally, the 4-day retrograde rotation in the Venus' atmosphere might be driven by such a periodic thermal forcing. In this work we revisited an existing theoretical model and validated it by means of direct numerical simulations (DNS). Furthermore, we expanded the analysis above the limits of the theory and studied travelling thermal waves in strongly convective flows.

Our results can be summarized as follows. The 2D simulations show excellent agreement with the theoretical model for low Rayleigh numbers (Ra). For larger Ra, the theory overestimates the magnitude of the zonal flows. However, the asymptotic scalings are still valid. The 3D system shows very similar characteristics than the 2D flows, therefore we provide further evidence for the relevance of this problem to natural systems. Finally, we show that the direction of the induced mean zonal flows can change. While it is always directed opposite to the travelling wave (retrograde) for low Ra flows, as the Ra increases the zonal flow is often found in a prograde state.