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arXiv · 1609.05026

Extreme dissipation event due to plume collision in a turbulent convection cell

Joerg Schumacher·Janet D. Scheel
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Abstract

An extreme dissipation event in the bulk of a closed three-dimensional turbulent convection cell is found to be correlated with a strong reduction of the large-scale circulation flow in the system that happens at the same time as a plume emission event from the bottom plate. The reduction in the large-scale circulation opens the possibility for a nearly frontal collision of down- and upwelling plumes and the generation of a high-amplitude thermal dissipation layer in the bulk. This collision is locally connected to a subsequent high-amplitude energy dissipation event in the form of a strong shear layer. Our analysis illustrates the impact of transitions in the large-scale structures on extreme events at the smallest scales of the turbulence, a direct link that is observed in a flow with boundary layers. We also show that detection of extreme dissipation events which determine the far-tail statistics of the dissipation fields in the bulk requires long-time integrations of the equations of motion over at least hundred convective time units.

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Joerg Schumacher, Janet D. Scheel. 2016-09-16. Extreme dissipation event due to plume collision in a turbulent convection cell. https://doi.org/10.1103/physreve.94.043104

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