Transition control in a three-dimensional boundary layer by direct attenuation of nonlinear crossflow vortices using plasma actuators |
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| Affiliation: | 1. Department of Cardiology, New Tokyo Hospital, Chiba, Japan;2. Harrington Heart and Vascular Institute, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH, United States;3. Center of Biostatistics and Bioinformatics, University of Mississippi Medical Center, Jackson, MS, United States;1. Research Institute of Health Sciences, Ouagadougou, Burkina Faso;2. Kaya Health and Demographic Surveillance System, Kaya, Burkina Faso;3. African Institute of Public Health, Ouagadougou, Burkina Faso;4. Directorate of Family Health and Nutrition, Ministry of Health and Public Hygiene of Guinea, Conakry, Guinea;5. Averting Maternal Death and Disability, Mailman School of Public Health, Columbia University, New York, USA |
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| Abstract: | 
Direct numerical simulations are used to probe the potential of plasma actuators to attenuate nonlinear steady crossflow vortices (CFVs). The investigated base flow mimics the three-dimensional boundary-layer flow of a swept wing. The plasma actuators are positioned at selected spanwise positions to weaken oncoming CFVs and thus the associated (secondary) instability. It is shown that both volume forcing against or in the direction of the crossflow (CF) can be effective, and a significant transition delay can be achieved. The spanwise position of the actuators should be such that the actuation-induced downdraft inhibits the CFV. The forcing in the direction of the CF does not reduce the mean CF, and an unfavourable spanwise position of the actuator may directly increase the strength of the CFV and eventually promote turbulence onset. The forcing against the CF never turned out to promote turbulence onset for all investigated positions, because of the favourable reduction of the mean CF. Adding then a second or third actuator downstream at appropriate spanwise positions can yield enhanced transition delay. |
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