Methods for Vortex Identification
(2012) In Master’s Theses in Mathematical Sciences FMA820 20121Mathematics (Faculty of Engineering)
- Abstract
- Initially, this paper presents an overview of the existing methods used for the identification of vortices in fluids, attempting to point out their different strengths and weaknesses. In addition, a new method is proposed to identify vortices directly from velocity field information. It defines a point inside a vortex as a point around which there is rotation. By looking at the velocity directions in the neighbourhood of a point we decide if there is rotation. A measure of the strength of rotation at the point is also introduced based on the magnitude of the velocity components in the neighbourhood. The method is tested on simulated data and performs well. Finally a Lagrangian identification method (Direct Lyapunov Exponents, DLE) is used... (More)
- Initially, this paper presents an overview of the existing methods used for the identification of vortices in fluids, attempting to point out their different strengths and weaknesses. In addition, a new method is proposed to identify vortices directly from velocity field information. It defines a point inside a vortex as a point around which there is rotation. By looking at the velocity directions in the neighbourhood of a point we decide if there is rotation. A measure of the strength of rotation at the point is also introduced based on the magnitude of the velocity components in the neighbourhood. The method is tested on simulated data and performs well. Finally a Lagrangian identification method (Direct Lyapunov Exponents, DLE) is used to attempt to calibrate the most widely used Eulerian method in order to match an objectively defined edge. The results here indicate that it might not be possible to find a threshold for this method to match the edges found using the DLE method. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/3241710
- author
- Holmén, Vivianne LU
- supervisor
- organization
- course
- FMA820 20121
- year
- 2012
- type
- H2 - Master's Degree (Two Years)
- subject
- publication/series
- Master’s Theses in Mathematical Sciences
- report number
- LUTFMA-3239-2012
- ISSN
- 1404-6342
- other publication id
- 2012:E47
- language
- English
- id
- 3241710
- date added to LUP
- 2014-06-27 17:33:40
- date last changed
- 2014-06-27 17:33:40
@misc{3241710, abstract = {{Initially, this paper presents an overview of the existing methods used for the identification of vortices in fluids, attempting to point out their different strengths and weaknesses. In addition, a new method is proposed to identify vortices directly from velocity field information. It defines a point inside a vortex as a point around which there is rotation. By looking at the velocity directions in the neighbourhood of a point we decide if there is rotation. A measure of the strength of rotation at the point is also introduced based on the magnitude of the velocity components in the neighbourhood. The method is tested on simulated data and performs well. Finally a Lagrangian identification method (Direct Lyapunov Exponents, DLE) is used to attempt to calibrate the most widely used Eulerian method in order to match an objectively defined edge. The results here indicate that it might not be possible to find a threshold for this method to match the edges found using the DLE method.}}, author = {{Holmén, Vivianne}}, issn = {{1404-6342}}, language = {{eng}}, note = {{Student Paper}}, series = {{Master’s Theses in Mathematical Sciences}}, title = {{Methods for Vortex Identification}}, year = {{2012}}, }