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Evolution and Features of Dust Devil-Like Vortices in Turbulent Rayleigh-Bénard Convection - An Experimental Study
  • Christian Kästner,
  • Julien David Schneider,
  • Ronald du Puits
Christian Kästner
Technische Universität Ilmenau

Corresponding Author:[email protected]

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Julien David Schneider
Technische Universität Ilmenau
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Ronald du Puits
Ilmenau University of Technology
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Abstract

We present an experimental study simulating atmospheric dust devils in a controlled laboratory experiment. Our work complements and extends the numerical work of Giersch and Raasch (2021) by experiments. Dust devils are thermal convective vortices with a vertical axis of rotation visualized by entrained soil particles. They evolve in the convective atmospheric boundary layer and are believed to substantially contribute to the aerosol transport into the atmosphere. Thus, genesis, size, lifetime and frequency of occurrence of dust devils are of particular research interest. Extensive experimental studies have been conducted by field measurements and laboratory experiments. Field measurements lack of unpredictable formation of dust devils and limited area to be observed. Hitherto laboratory experiments, which frequently generate dust devils with fans, lack of generic conditions in the atmosphere. In our study, we investigate dust devil-like vortices in a large-scale Rayleigh-Bénard experiment. This set-up mimics the natural process of dust devil formation as closest to reality so far. The flow measurement was carried out by particle tracking velocimetry using neutrally buoyant soap bubbles. We identified initial dust devil-like vortices by eyes from the Langrangian velocity field and in a later more sophisticated analysis by a specific algorithm from the Eulerian velocity field. We analyzed their frequency of occurrence, observation time and size. With our work, we could demonstrate that turbulent Rayleigh-Bénard convection is an appropriate model to mimic the natural process of the genesis of dust devil-like vortices in the thermal boundary layer of the atmosphere without any artificial stimulation.