Vortex-identification methods from a different perspective

0496425 - ÚH 2019 RIV US eng C - Conference Paper (international conference)
Kolář, Václav - Šístek, Jakub
Vortex-identification methods from a different perspective.
The 29th International Symposium on Transport Phenomena (ISTP29). Honolulu: PCTFE, 2018. ISBN N.
[International Symposium on Transport Phenomena (ISTP29) /29./. Honolulu (US), 30.10.2018-02.11.2018]
R&D Projects: GA ČR(CZ) GA18-09628S
Institutional support: RVO:67985874 ; RVO:67985840
Keywords : vortex * vortex identification * vortex-identification methods * vortical flow * vortical structures
OECD category: Fluids and plasma physics (including surface physics); Pure mathematics (MU-W)

A more universal classification of vortex-identification methods starts with the basic fluid-mechanical approach adopted: Lagrangian or Eulerian. Eulerian methods can be further sub-classified as local (pointwise) or non-local. The Eulerian local methods aim either at the vortex volumetric region (region-type schemes) or at the vortexcore skeleton (line-type schemes). Most of the Eulerian region-type methods (including some Lagrangian) are based on one vortex feature to derive a yes/no criterion which may provide the intensity measure of local vortex motion inside the vortex region, however, no applicable quantitative information outside the vortex region. The present paper aims to distinguish and emphasize those vortex-identification tools which are simultaneously and adequately informative outside the vortex regions, that is, basically covering the whole flow domain and especially indicating regions of strong strain-rate or shearing. This is due to a certain duality property of criterial measures applied (Q-criterion, MZ-criterion) or due to a rational velocity-gradient analysis of a wider applicability (triple decomposition method, corotation/contrarotation scheme). The latter provide complex information at each point of the flow field while the former distinguish two or more qualitatively different non-overlapping flow regions. Some illustrative vortical-flow examples are included.
Permanent Link: http://hdl.handle.net/11104/0289207