caa a22 4500 606198466 CHVBK 20210128100934.0 cr unu---uuuuu 210128e20150801xx s 000 0 eng 10.1007/s00348-015-2014-7 doi (NATIONALLICENCE)springer-10.1007/s00348-015-2014-7 Vorticity transport and the leading-edge vortex of a plunging airfoil [Elektronische Daten] [Azar Eslam Panah, James Akkala, James Buchholz] The three-dimensional flow field was experimentally characterized for a nominally two-dimensional flat-plate airfoil plunging at large amplitude and reduced frequencies, using three-dimensional reconstructions of planar PIV data at a chord-based Reynolds number of 10,000. Time-resolved, instantaneous PIV measurements reveal that secondary vorticity, of opposite sign to the primary vortex, is intermittently entrained into the leading-edge vortex (LEV) throughout the downstroke, with the rate of entrainment increasing toward the end of the stroke when the leading-edge shear layer weakens. A planar vorticity transport analysis around the LEV indicated that, during the downstroke, the surface vorticity flux due to the pressure gradient is consistently about half that due to the leading-edge shear layer for all parameter values investigated, demonstrating that production and entrainment of secondary vorticity is an important mechanism regulating LEV strength. A small but non-negligible vorticity source was also attributed to spanwise flow toward the end of the downstroke. Aggregate vortex tilting is notably more significant for higher plunge frequencies, suggesting that the vortex core is more three-dimensional. Springer-Verlag Berlin Heidelberg, 2015 Eslam Panah Azar Department of Mechanical and Industrial Engineering IIHR - Hydroscience and Engineering, University of Iowa, 52242, Iowa City, IA, USA aut Akkala James Department of Mechanical and Industrial Engineering IIHR - Hydroscience and Engineering, University of Iowa, 52242, Iowa City, IA, USA aut Buchholz James Department of Mechanical and Industrial Engineering IIHR - Hydroscience and Engineering, University of Iowa, 52242, Iowa City, IA, USA aut Experiments in Fluids Springer Berlin Heidelberg 56/8(2015-08-01), 1-15 0723-4864 56:8<1 2015 56 348 https://doi.org/10.1007/s00348-015-2014-7 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00348-015-2014-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Eslam Panah Azar Department of Mechanical and Industrial Engineering IIHR - Hydroscience and Engineering, University of Iowa, 52242, Iowa City, IA, USA aut NATIONALLICENCE 700 1- Akkala James Department of Mechanical and Industrial Engineering IIHR - Hydroscience and Engineering, University of Iowa, 52242, Iowa City, IA, USA aut NATIONALLICENCE 700 1- Buchholz James Department of Mechanical and Industrial Engineering IIHR - Hydroscience and Engineering, University of Iowa, 52242, Iowa City, IA, USA aut NATIONALLICENCE 773 0- Experiments in Fluids Springer Berlin Heidelberg 56/8(2015-08-01), 1-15 0723-4864 56:8<1 2015 56 348