scholarly journals Unsteady Force Generation and Vortex Dynamics of Pitching and Plunging Flat Plates at Low Reynolds Number

Author(s):  
Yeon Sik Baik ◽  
Luis Bernal ◽  
Wei Shyy ◽  
Michael Ol
2021 ◽  
Author(s):  
Bastav Borah ◽  
Anand Verma ◽  
Vinayak Kulkarni ◽  
Ujjwal K. Saha

Abstract Vortex shedding phenomenon leads to a number of different features such as flow induced vibrations, fluid mixing, heat transfer and noise generation. With respect to aerodynamic application, the intensity of vortex shedding and the size of vortices play an essential role in the generation of lift and drag forces on an airfoil. The flat plates are known to have a better lift-to-drag ratio than conventional airfoils at low Reynolds number (Re). A better understanding of the shedding behavior will help aerodynamicists to implement flat plates at low Re specific applications such as fixed-wing micro air vehicle (MAV). In the present study, the shedding of vortices in the wake of a flat plate at low incidence has been studied experimentally in a low-speed subsonic wind tunnel at a Re of 5 × 104. The velocity field in the wake of the plate is measured using a hot wire anemometer. These measurements are taken at specific points in the wake across the flow direction and above the suction side of the flat plate. The velocity field is found to oscillate with one dominant frequency of fluctuation. The Strouhal number (St), calculated from this frequency, is computed for different angles of attack (AoA). The shedding frequency of vortices from the trailing edge of the flat plate has a general tendency to increase with AoA. In this paper, the generation and subsequent shedding of leading edge and trailing edge vortices in the wake of a flat plate are discussed.


1983 ◽  
Vol 105 (1) ◽  
pp. 166-171 ◽  
Author(s):  
R. E. Roadman ◽  
R. I. Loehrke

The flow between pairs of flat plates was studied experimentally to gain insight into the operation of compact heat exchangers with interrupted surfaces. The plates were tested at low Reynolds number in both water and air streams. The investigation focused on the region of transition from steady to unsteady laminar flow between plates. A critical velocity was determined at which periodic oscillations were first observed. This velocity depends strongly on the thickness of the plates, t, plate length, L, and plate separation distance and weakly on flow disturbance level. Data for a range of geometries, 4 ≤ L/t ≤ 159, are correlated using plate wake width as a single plate length scale. The downstream plate was found to have a pronounced upstream influence on the critical velocity. In a low-disturbance-level stream the critical velocity may be lower than that required to produce detectable oscillations at the same point in the upstream plate wake in absence of the second plate. This feedback effect may be responsible for the relative insensitivity of the results to the turbulence level in the free stream.


2017 ◽  
Vol 58 (11) ◽  
Author(s):  
Étienne Mangeol ◽  
Daichi Ishiwaki ◽  
Nicolas Wallisky ◽  
Keisuke Asai ◽  
Taku Nonomura

Author(s):  
Eliot Schuhler ◽  
Bertrand Lecordier ◽  
Jérôme Yon ◽  
Gilles Godard ◽  
Alexis Coppalle

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