TY - JOUR A1 - Kasten, Jens A1 - Reininghaus, Jan A1 - Hotz, Ingrid A1 - Hege, Hans-Christian A1 - Noack, Bernd A1 - Daviller, Guillaume A1 - Morzyński, Marek T1 - Acceleration feature points of unsteady shear flows JF - Archives of Mechanics N2 - A framework is proposed for extracting features in 2D transient flows, based on the acceleration field to ensure Galilean invariance. The minima of the acceleration magnitude, i.e. a superset of the acceleration zeros, are extracted and discriminated into vortices and saddle points --- based on the spectral properties of the velocity Jacobian. The extraction of topological features is performed with purely combinatorial algorithms from discrete computational topology. The feature points are prioritized with persistence, as a physically meaningful importance measure. These features are tracked in time with a robust algorithm for tracking features. Thus a space-time hierarchy of the minima is built and vortex merging events are detected. The acceleration feature extraction strategy is applied to three two-dimensional shear flows: (1) an incompressible periodic cylinder wake, (2) an incompressible planar mixing layer and (3) a weakly compressible planar jet. The vortex-like acceleration feature points are shown to be well aligned with acceleration zeros, maxima of the vorticity magnitude, minima of pressure field and minima of λ2. Y1 - 2016 VL - 68 IS - 1 SP - 55 EP - 80 ER - TY - GEN A1 - Kasten, Jens A1 - Reininghaus, Jan A1 - Hotz, Ingrid A1 - Hege, Hans-Christian A1 - Noack, Bernd A1 - Daviller, Guillaume A1 - Morzyński, Marek T1 - Acceleration feature points of unsteady shear flows N2 - A framework is proposed for extracting features in 2D transient flows, based on the acceleration field to ensure Galilean invariance. The minima of the acceleration magnitude, i.e. a superset of the acceleration zeros, are extracted and discriminated into vortices and saddle points --- based on the spectral properties of the velocity Jacobian. The extraction of topological features is performed with purely combinatorial algorithms from discrete computational topology. The feature points are prioritized with persistence, as a physically meaningful importance measure. These features are tracked in time with a robust algorithm for tracking features. Thus a space-time hierarchy of the minima is built and vortex merging events are detected. The acceleration feature extraction strategy is applied to three two-dimensional shear flows: (1) an incompressible periodic cylinder wake, (2) an incompressible planar mixing layer and (3) a weakly compressible planar jet. The vortex-like acceleration feature points are shown to be well aligned with acceleration zeros, maxima of the vorticity magnitude, minima of pressure field and minima of λ2. T3 - ZIB-Report - 15-65 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-58397 SN - 1438-0064 ER - TY - GEN A1 - Kasten, Jens A1 - Hotz, Ingrid A1 - Hege, Hans-Christian ED - Peikert, Ronald ED - Hauser, Helwig ED - Carr, Hamish ED - Fuchs, Raphael T1 - On the Elusive Concept of Lagrangian Coherent Structures T2 - Topological Methods in Data Analysis and Visualization II Y1 - 2012 U6 - https://doi.org/10.1007/978-3-642-23175-9_14 SP - 207 EP - 220 PB - Springer ER - TY - CHAP A1 - Kasten, Jens A1 - Zoufahl, Andre A1 - Hege, Hans-Christian A1 - Hotz, Ingrid T1 - Analysis of Vortex Merge Graphs T2 - VMV 2012: Vision, Modeling and Visualization Y1 - 2012 U6 - https://doi.org/10.2312/PE/VMV/VMV12/111-118 SP - 111 EP - 118 PB - Eurographics Association ER - TY - CHAP A1 - Kasten, Jens A1 - Hotz, Ingrid A1 - Noack, Bernd A1 - Hege, Hans-Christian T1 - Vortex Merge Graphs in Two-dimensional Unsteady Flow Fields T2 - EuroVis – Short Papers Y1 - 2012 UR - http://diglib.eg.org/EG/DL/PE/EuroVisShort/EuroVisShort2012/001-005.pdf U6 - https://doi.org/10.2312/PE/EuroVisShort/EuroVisShort2012/001-005 SP - 1 EP - 5 PB - Eurographics Association CY - Vienna, Austria ER - TY - JOUR A1 - Hege, Hans-Christian A1 - Kasten, Jens A1 - Hotz, Ingrid T1 - Distillation and Visualization of Spatiotemporal Structures in Turbulent Flow Fields JF - J. Phys. Y1 - 2011 U6 - https://doi.org/10.1088/1742-6596/318/6/062009 VL - 318 SP - 062009 ET - 6 ER - TY - JOUR A1 - Kasten, Jens A1 - Reininghaus, Jan A1 - Hotz, Ingrid A1 - Hege, Hans-Christian T1 - Two-Dimensional Time-Dependent Vortex Regions Based on the Acceleration Magnitude JF - IEEE Transactions on Visualization and Computer Graphics Y1 - 2011 VL - 17 IS - 12 SP - 2080 EP - 2087target ER - TY - GEN A1 - Kasten, Jens A1 - Hotz, Ingrid A1 - Noack, Bernd A1 - Hege, Hans-Christian ED - Pascucci, Valerio ED - Tricoche, Xavier ED - Hagen, Hans ED - Tierny, Julien T1 - On the Extraction of Long-living Features in Unsteady Fluid Flows T2 - Topological Methods in Data Analysis and Visualization Y1 - 2011 SN - 978-3-642-15013-5 U6 - https://doi.org/10.1007/978-3-642-15014-2_10 SP - 115 EP - 126 PB - Springer CY - Berlin ER - TY - JOUR A1 - Lacarelle, Arnaud A1 - P. Moeck, Jonas A1 - Paschereit, Christian A1 - Gelbert, Gregor A1 - King, Rudibert A1 - M. Luchtenburg, Dirk A1 - Noack, Bernd R. A1 - Kasten, Jens A1 - Hege, Hans-Christian T1 - Modeling a Fuel/Air Mixing to Control the Pressure Pulsations and NOx Emissions in a Lean Premixed Combustor JF - Active Flow Control II Y1 - 2010 U6 - https://doi.org/10.1007/978-3-642-11735-0_20 VL - 108 SP - 307 EP - 321 PB - Springer, Berlin ER - TY - CHAP A1 - Kasten, Jens A1 - Weinkauf, Tino A1 - Petz, Christoph A1 - Hotz, Ingrid A1 - Noack, Bernd R. A1 - Hege, Hans-Christian T1 - Extraction of Coherent Structures from Natural and Actuated Flows T2 - Active Flow Control II Y1 - 2010 SN - 978-3-642-11734-3 U6 - https://doi.org/10.1007/978-3-642-11735-0_24 VL - 108 SP - 373 EP - 387 PB - Springer, Berlin ER - TY - GEN A1 - Kasten, Jens A1 - Reininghaus, Jan A1 - Oberleithner, Kilian A1 - Hotz, Ingrid A1 - Noack, Bernd A1 - Hege, Hans-Christian T1 - Flow over a Cavity – Evolution of the Vortex Skeleton Y1 - 2010 PB - Visualization at 28th Annual Gallery of Fluid Motion exhibit, held at the 63th Annual Meeting of the American Physical Society, Division of Fluid Dynamics (Long Beach, CA, USA, November 21-23, 2010). ER - TY - JOUR A1 - Kasten, Jens A1 - Petz, Christoph A1 - Hotz, Ingrid A1 - Hege, Hans-Christian A1 - Noack, Bernd A1 - Tadmor, Gilead T1 - Lagrangian Feature Extraction of the Cylinder Wake JF - Physics of Fluids Y1 - 2010 U6 - https://doi.org/10.1063/1.3483220 VL - 22 IS - 9 SP - 091108 ER - TY - JOUR A1 - Petz, Christoph A1 - Kasten, Jens A1 - Prohaska, Steffen A1 - Hege, Hans-Christian T1 - Hierarchical Vortex Regions in Swirling Flow JF - Computer Graphics Forum Y1 - 2009 VL - 28 IS - 3 SP - 863 EP - 870 ER - TY - CHAP A1 - Kasten, Jens A1 - Petz, Christoph A1 - Hotz, Ingrid A1 - Noack, Bernd R. A1 - Hege, Hans-Christian ED - Magnor, Marcus ED - Rosenhahn, Bodo ED - Theisel, Holger T1 - Localized Finite-time Lyapunov Exponent for Unsteady Flow Analysis T2 - Vision Modeling and Visualization Y1 - 2009 SN - 978-3-9804874-8-1 VL - 1 SP - 265 EP - 274 PB - Universität Magdeburg, Inst. f. Simulation u. Graph. ER -