A Study of the Fluid Force due to Side Wind on a Railroad Car by Three-Dimensional Discrete Vortex Method.

2000 ◽  
Vol 66 (644) ◽  
pp. 1021-1028
Author(s):  
Michihisa TSUTAHARA ◽  
Yujiro TATSUMI ◽  
Tatsuo MAEDA ◽  
Minoru SUZUKI
Keyword(s):  
Three Dimensional ◽  
Vortex Method ◽  
Discrete Vortex ◽  
Fluid Force ◽  
Discrete Vortex Method

Prediction of Roll Damping in the Frequency Domain Using the Discrete Vortex Method

2010 ◽  
Author(s):  
Mohammad Hajiarab ◽  
J. Michael R. Graham ◽  
Martin Downie
Keyword(s):  
Frequency Domain ◽  
Model Test ◽  
Theoretical Approach ◽  
Three Dimensional ◽  
Separated Flow ◽  
Vortex Method ◽  
Roll Damping ◽  
Discrete Vortex ◽  
Discrete Vortex Method ◽  
Good Agreement

This paper describes a theoretical approach to predict roll damping for a three-dimensional barge shaped vessel in the frequency domain by matching a simple discrete vortex method (DVM), describing local separated flow, to an inviscid 3-D seakeeping code. The results are compared with model test experiments to demonstrate validity of the method. A good agreement between the model test RAO and the damped RAO is achieved.

Numerical Analysis of Unsteady Flow in the Weis-Fogh Mechanism by the 3D Discrete Vortex Method With GRAPE3A

1997 ◽  
Vol 119 (1) ◽  
pp. 96-102 ◽  
Author(s):  
Kideok Ro ◽  
Michihisa Tsutahara
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Leading Edge ◽  
Vortex Method ◽  
Reynolds Numbers ◽  
Discrete Vortex ◽  
Discrete Vortex Method ◽  
Trailing Edges ◽  
Induced Velocity ◽  
Vortex Systems

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.

Flows past a rotating circular cylinder by the discrete vortex method.

1989 ◽  
Vol 9 (34) ◽  
pp. 273-276
Author(s):  
Takeyoshi Kimura ◽  
Michihisa Tsutahara ◽  
Zhong-yi Wang ◽  
Hiroshi Ishii
Keyword(s):  
Circular Cylinder ◽  
Vortex Method ◽  
Discrete Vortex ◽  
Discrete Vortex Method ◽  
Rotating Circular Cylinder
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