Flow control of weakly non-parallel flows: application to trailing vortices. (1st June 2017)

• Record Type: Journal Article
• Authors: Viola, F.; Pezzica, E.; Iungo, G. V.; Gallaire, F.; Camarri, S.
• Is Part Of: Journal of fluid mechanics. Volume 822(2017)
• Page Start: 342
• Page End: 363
• Publication Date: 2017-06-01
• Subjects: flow control, -- instability control, -- vortex instability; Fluid mechanics -- Periodicals; 532.005
• DOI: 10.1017/jfm.2017.281
• Languages: English
• ISSNs: 0022-1120

Abstract

Abstract : A general formulation is proposed to control the integral amplification factor of harmonic disturbances in weakly non-parallel amplifier flows. The sensitivity of the local spatial stability spectrum to a base-flow modification is first determined, generalizing the results of Bottaro et al. ( J. Fluid Mech., vol. 476, 2003, pp. 293–302). This result is then used to evaluate the sensitivity of the overall spatial growth to a modification of the inlet flow condition. This formalism is applied to a non-parallel Batchelor vortex, which is a well-known model for trailing vortices generated by a lifting wing. The resulting sensitivity map indicates the optimal modification of the inlet flow condition enabling the stabilization of the helical modes. It is shown that the control, formulated using a single linearization of the flow dynamics carried out on the uncontrolled configuration, successfully reduces the total spatial amplification of all convectively unstable disturbances.