Preprints
https://doi.org/10.5194/egusphere-2023-2637
https://doi.org/10.5194/egusphere-2023-2637
06 Dec 2023
 | 06 Dec 2023
Status: this preprint is open for discussion.

New straightforward formulae for the settling speed of prolate spheroids in the atmosphere: theoretical background and implementation in AerSett v2.0.2

Sylvain Mailler, Sotirios Mallios, Arineh Cholakian, Vassilis Amiridis, Laurent Menut, and Romain Pennel

Abstract. We propose two direct expressions to calculate the settling speed of atmospheric particles with prolate spheroidal shapes under the hypothesis of horizontal and vertical orientation. The first formulation is extremely simple and based on theoretical arguments only. The second method, valid for particles with mass-median diameter up to 1000 µm, is based on recent heuristic drag expressions based on CFD numeric simulations. We show that these two formulations show equivalent results within 2 % for deq ≤ 100 µm, and within 10 % for particles with deq ≤ 500 µm falling with a horizontal orientation, showing that the first, more simple method is suitable for virtually all atmospheric aerosols, provided their shape can be adequately described as a prolate spheroid. Finally, in order to facilitate the use of our results in chemistry-transport models, we provide an implementation of the first of these methods in AerSett v2.0.2, a module written in Fortran.

Sylvain Mailler, Sotirios Mallios, Arineh Cholakian, Vassilis Amiridis, Laurent Menut, and Romain Pennel

Status: open (extended)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-2637', Carlos Alvarez Zambrano, 17 Jan 2024 reply
  • AC1: 'Answer to Reviewer Comment by Carlos Alvarez Zambrano on gusphere-2023-2637', Sylvain Mailler, 25 Jan 2024 reply
    • RC2: 'Reply on AC1', Carlos Alvarez Zambrano, 05 Feb 2024 reply
Sylvain Mailler, Sotirios Mallios, Arineh Cholakian, Vassilis Amiridis, Laurent Menut, and Romain Pennel

Model code and software

AerSett v2.0.2 S. Mailler, L. Menut, A. Cholakian, and R. Pennel https://doi.org/10.5281/zenodo.10261378

Interactive computing environment

FreeFall v2.1 S. Mailler https://doi.org/10.5281/zenodo.10254770

Sylvain Mailler, Sotirios Mallios, Arineh Cholakian, Vassilis Amiridis, Laurent Menut, and Romain Pennel

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Short summary
We propose two direct expressions to calculate the settling speed of atmospheric particles with prolate spheroidal shapes. The first formulation is extremely simple and based on theoretical arguments only, while the second one is based on CFD calculations. We show that the first method is suitable for virtually all atmospheric aerosols, provided their shape can be adequately described as a prolate spheroid, and we provide an implementation of the first method in AerSett v2.0.2.