The three-dimensional flows in the Weis-Fogh mechanism are studied by flow visualization and numerical simulation by a discrete vortex method. In this mechanism, two wings open, touching their trailing edges (fling), and rotate in opposite directions in the horizontal plane. At the “fling” stage, the flow separates at the leading edge and the tip of each wing. Then they rotate, and the flow separates also at the trailing edges. The structure of the vortex systems shed from the wings is very complicated and their effect on the forces on the wings have not yet been clarified. Discrete vortex method, especially the vortex stick method, is employed to investigate the vortex structure in the wake of the two wings. The wings are represented by lattice vortices, and the shed vortices are expressed by discrete three-dimensional vortex sticks. In this calculation, the GRAPE3A hardware is used to calculate at high speed the induced velocity of the vortex sticks and the viscous diffusion of fluid is represented by the random walk method. The vortex distributions and the velocity field are calculated. The pressure is estimated by the Bernoulli equation, and the lift and moment on the wing are also obtained. However, the simulations, especially those for various Reynolds numbers, should be treated with caution, because there is no measurement to compare them with and the discrete vortex method is approximate due to rudimentary modeling of viscosity.
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March 1997
Research Papers
Numerical Analysis of Unsteady Flow in the Weis-Fogh Mechanism by the 3D Discrete Vortex Method With GRAPE3A
Kideok Ro,
Kideok Ro
Department of Marine Engineering, Fisheries College, Gyeongsang National University, 445 Inpyung-dong, Tongyeong, Kyungnam 650-160, Korea
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Michihisa Tsutahara
Michihisa Tsutahara
Graduate School of Science and Technology, Kobe University, Rokkodai-cho 1-1, Nada-ku, Kobe 657, Japan
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Kideok Ro
Department of Marine Engineering, Fisheries College, Gyeongsang National University, 445 Inpyung-dong, Tongyeong, Kyungnam 650-160, Korea
Michihisa Tsutahara
Graduate School of Science and Technology, Kobe University, Rokkodai-cho 1-1, Nada-ku, Kobe 657, Japan
J. Fluids Eng. Mar 1997, 119(1): 96-102 (7 pages)
Published Online: March 1, 1997
Article history
Received:
February 14, 1996
Revised:
July 22, 1996
Online:
December 4, 2007
Citation
Ro, K., and Tsutahara, M. (March 1, 1997). "Numerical Analysis of Unsteady Flow in the Weis-Fogh Mechanism by the 3D Discrete Vortex Method With GRAPE3A." ASME. J. Fluids Eng. March 1997; 119(1): 96–102. https://doi.org/10.1115/1.2819125
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