Strömungskontrolle unter konstantem Leistungseintrag
Zusammenfassung der Projektergebnisse
In the simulation of a flow problem, it is common to prescribe the volumetric flow rate, obtaining the pressure drop in the system considered as a result. Depending on the question at hand, one might also prescribe the pressure drop and obtain the flow rate as a result. Within this project, we have developed an alternative strategy, that consists in running simulations under a prescribed constant power input (CPI) and thus obtain flow rate and pressure drop as a result. The CPI concept becomes particularly important and appealing in the context of flow control, where a comparison between control-on and control-off conditions has to be made. The result of such a comparison can be strongly influenced by the choice we make of how to compare two flows. We can decide to compare two flows with the same flow rate (CFR), with the same pressure gradient (CPG) or with the same power input (CPI). If CPI is set up in such a way that the power expenditure of the control is included, it enables us to directly determine the possibility of net power savings. The corresponding data set for the controlled flow states, in which the respective maximum flow rate increase compared to the uncontrolled flow at the same total power input is realized for each control technique, has been made publicly available This data set allows investigating whether it is possible to extract generalized statements about drag reduced flows. In the project the generated data has been used to tackle two consecutive fundamental questions regarding the physics of drag reduction in turbulent flows from the energetic standpoint. The first question, which previously only found contradictory answers in literature, is the following: Does drag-reducing flow control modify the way energy is dissipated in a turbulent flow? The naturally following second question addressed with the generated data set is how drag reduction techniques achieve these favorable modifications.
Projektbezogene Publikationen (Auswahl)
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Numerical simulation of turbulent duct flows with constant power input. Journal of Fluid Mechanics, 750, 191-209.
Hasegawa, Yosuke; Quadrio, Maurizio & Frohnapfel, Bettina
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Skin Friction Drag Reduction in Turbulent Flows – The Art of Comparison. Invited Keynote Lecture, 15th European Turbulence Conference 2015, August 25-28, Delft, The Netherlands
Frohnapfel, B.
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Does the choice of the forcing term affect flow statistics in DNS of turbulent channel flow?. European Journal of Mechanics - B/Fluids, 55, 286-293.
Quadrio, Maurizio; Frohnapfel, Bettina & Hasegawa, Yosuke
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Energy transfer rates in turbulent channels with drag reduction at constant power input. European Drag Reduction and Flow Control Meeting EDRFCM 2017, April 2017, Rome, Italy
Gatti, D., Quadrio, M., Hasegawa, Y., Frohnapfel, B. & Cimarelli, A.
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Scale Energy Fluxes In Turbulent Channels With Drag Reduction At Constant Power Input. 16th European Turbulence Conference 2015, August 21-24, Stockholm, Sweden
Gatti, D., Remigi, A., Frohnapfel, B., Hasegawa, H., Cimarelli, A. & Quadrio, M.
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Small scale dynamics of a shearless turbulent/non-turbulent interface in dilute polymer solutions. Physics of Fluids, 29(7).
Cocconi, G.; De Angelis, E.; Frohnapfel, B.; Baevsky, M. & Liberzon, A.
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Study of Energetics in Drag-Reduced Turbulent Channel Flows. Springer Proceedings in Physics, 219-225. Springer International Publishing.
Gatti, Davide; Quadrio, Maurizio; Cimarelli, Andrea; Hasegawa, Yosuke & Frohnapfel, Bettina
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Global energy fluxes in turbulent channels with flow control. Journal of Fluid Mechanics, 857, 345-373.
Gatti, Davide; Cimarelli, Andrea; Hasegawa, Yosuke; Frohnapfel, Bettina & Quadrio, Maurizio
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Space and scale fluxes of Reynolds stresses in turbulent channel flows. Annual Meeting of the International Association of Applied Mathematics and Mechanics GAMM, Braunschweig, Germany
Chiarini, A., Frohnapfel, B., Quadrio, M., Cimarelli, A., Hasegawa, Y. & Gatti, D.
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Turbulent flow statistics at Constant Power Input (CPI) with and without drag reduction. Repository KITOpen
Gatti, D., Frohnapfel, B. & Quadrio, M.
