Repository: Freie Universität Berlin, Math Department

The curious nature of hairpin vortices. Gallery of Fluid Motion.

Harikrishnan, A. and Ansorge, C. and Klein, R. and Vercauteren, N. (2020) The curious nature of hairpin vortices. Gallery of Fluid Motion. In: 73th Annual Meeting of the APS Division of Fluid Dynamics, November 22, 2020 — November 24, 2020, Chicago, IL Virtual.

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Official URL: https://doi.org/10.1103/APS.DFD.2020.GFM.P0019

Abstract

The Direct Numerical Simulation (DNS) of an Ekman flow is shown here. It describes the Atmospheric Boundary Layer (ABL) which is the lowest part of the troposphere in direct contact with the Earth's surface. Applying the vorticity magnitude on xy or xz plane reveals large regions where turbulence is absent in the highly stratified (HS) case (first column of images), a feature which is not present in the neutrally stratified (NS) case (second column of images). Curiously, if we randomly extract Q-criterion structures from both cases, the hairpins from the HS case appear to be more organized i.e. the head of the hairpin points towards a certain direction. The final two rows shows several hairpins extracted with Multilevel Percolation (MLP). The first row shows their size measured in terms of ???? (boundary layer height under neutral conditions). The second row shows their position in terms of y+ (viscous wall units). The Reynolds number is described in terms of the geostrophic wind velocity (G) and ???? as Re = G????/ν.

Item Type:Conference or Workshop Item (Poster)
Subjects:Mathematical and Computer Sciences > Mathematics > Applied Mathematics
Divisions:Department of Mathematics and Computer Science > Institute of Mathematics
ID Code:2482
Deposited By: Ulrike Eickers
Deposited On:11 Dec 2020 13:09
Last Modified:14 Jan 2021 13:34

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