@conference_item {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/97268, title ="Unsteadiness in Flow over a Flat Plate at Angle-of-Attack at Low Reynolds Numbers", author = "Taira, Kunihiko and Dickson, William B.", month = "January", year = "2007", url = "https://resolver.caltech.edu/CaltechAUTHORS:20190718-165127033", note = "© 2007 by the authors. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. \n\nPublished Online: 18 Jun 2012. \n\nWork supported by a Multidisciplinary Research Initiative from the United States Air Force Office of Scientific Research (FA9550-05-1-0369, Program Manager: Dr. Fariba Fahroo).", revision_no = "9", abstract = "Flow over an impulsively started low-aspect-ratio flat plate at angle-of-attack is investigated for a Reynolds number of 300. Numerical simulations, validated by a companion experiment, are performed to study the influence of aspect ratio, angle of attack, and planform geometry on the interaction of the leading-edge and tip vortices and resulting lift and drag coefficients. Aspect ratio is found to significantly influence the wake pattern and the force experienced by the plate. For large aspect ratio plates, leading-edge vortices evolved into hairpin vortices that eventually detached from the plate, interacting with the tip vortices in a complex manner. Separation of the leading-edge vortex is delayed to some extent by having convective transport of the spanwise vorticity as observed in flow over elliptic, semicircular, and delta-shaped planforms. The time at which lift achieves its maximum is observed to be fairly constant over different aspect ratios, angles of attack, and planform geometries during the initial transient. Preliminary results are also presented for flow over plates with steady actuation near the leading edge.", }