Journal ArticleDOI
The formation and evolution of synthetic jets
Barton L. Smith,Ari Glezer +1 more
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In this article, a nominally plane turbulent jet is synthesized by the interactions of a train of counter-rotating vortex pairs that are formed at the edge of an orifice by the time-periodic motion of a flexible diaphragm in a sealed cavity.Abstract:
A nominally plane turbulent jet is synthesized by the interactions of a train of counter-rotating vortex pairs that are formed at the edge of an orifice by the time-periodic motion of a flexible diaphragm in a sealed cavity. Even though the jet is formed without net mass injection, the hydrodynamic impulse of the ejected fluid and thus the momentum of the ensuing jet are nonzero. Successive vortex pairs are not subjected to pairing or other subharmonic interactions. Each vortex of the pair develops a spanwise instability and ultimately undergoes transition to turbulence, slows down, loses its coherence and becomes indistinguishable from the mean jet flow. The trajectories of vortex pairs at a given formation frequency scale with the length of the ejected fluid slug regardless of the magnitude of the formation impulse and, near the jet exit plane, their celerity decreases monotonically with streamwise distance while the local mean velocity of the ensuing jet increases. In the far field, the synthetic jet i...read more
Citations
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Journal ArticleDOI
Two-Dimensional Synthetic Jet Simulation
Conrad Y. Lee,David Goldstein +1 more
TL;DR: In this paper, direct numerical simulation was used to model an array of two-dimensional synthetic slot jets pulsing into initially quiescent e ow. The results near the slots were compared with experimental data and found to be in good agreement.
Journal ArticleDOI
A piezoelectrically actuated micro synthetic jet for active flow control
TL;DR: In this paper, a piezoelectric synthetic jet actuator was used for boundary layer flow control and the results obtained showed a significant enhancement of the jet effectiveness by forcing the boundary layer flows at the natural instability frequency.
Journal ArticleDOI
Frequency response of a synthetic jet cavity
TL;DR: In this paper, the effect of excitation frequency on the synthetic jet flow is studied for cavities of different depths and for orifices of different diameters, and the results are expected to be useful for designing synthetic jet cavity.
Book
Summary of the 2004 Cfd Validation Workshop on Synthetic Jets and Turbulent Separation Control
TL;DR: A computational fluid dynamics validation workshop for synthetic jets and turbulent separation control (CFDVAL2004) was held in Williamsburg, Virginia in March 2004 as mentioned in this paper, where three cases were investigated: synthetic jets into quiescent air, synthetic jet into a turbulent boundary layer crossflow, and flow over a hump model with no-flow control, steady suction, and oscillatory control.
Journal ArticleDOI
Bluff body drag manipulation using pulsed jets and Coanda effect
TL;DR: In this article, the impact of fluidic actuation on the wake and drag of a three-dimensional blunt body is investigated experimentally, and the results encourage further development of fluid control to improve the aerodynamics of road vehicles and provide a complementary insight into the relation between wake dynamics and drag.
References
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Journal ArticleDOI
An Album of Fluid Motion
Milton van Dyke,Frank M. White +1 more
TL;DR: In this paper, the authors present a visualisation de l'ecoulement for tourbillon and dynamique des: fluides, aubes, cylindre, instabilite.
Journal ArticleDOI
Streamwise vortex structure in plane mixing layers
Luis P. Bernal,Anatol Roshko +1 more
TL;DR: In this paper, it is shown that superimposed on the primary, spanwise vortex structure there is a secondary, steam wise vortex structure, and the spatial organization of the secondary structure produces a well-defined spanwise entrainment pattern in which fluid from each stream is preferentially entrained at different spanwise locations.
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The planar turbulent jet
Ephraim Gutmark,Israel Wygnanski +1 more
TL;DR: In this article, hot-wire measurements in a plane incompressible jet are reported, where the flow was found to be self-preserving beyond x/d > 40 and measurements were made up to x/D = 120.
Journal ArticleDOI
The structure of a self-preserving turbulent plane jet
TL;DR: The structure of a self-preserving turbulent plane jet exhausting into a slow-moving parallel airstream is studied in this paper, where results of turbulence measurements and the structure is compared with that of the plane wake.
Journal ArticleDOI
Preferred modes and the spreading rates of jets
Ephraim Gutmark,Chih-Ming Ho +1 more
TL;DR: In this article, it is suggested that extremely low-level spatially coherent disturbances in individual facilities change the initial conditions of a laminar shear layer and result in the discrepancies reported in the literature.