A numerical simulation of hydrodynamic forces of ground-effect problem using Lagrange's equation of motion

Yang, S. A.; Luh, P.

doi:10.1002/(sici)1097-0363(19980330)26:6<725::aid-fld713>3.0.co;2-3

Cited by 7 publications

(5 citation statements)

References 31 publications

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“…It also has applications for high-speed trains moving in very close proximity (cf. Kikuchi, Maeda & Yanagizawa 1996;Yang & Luh 1998;Liu 2004). In fact, the attraction between two trains translating at speeds of 360 mph in very close proximity may be three orders of magnitude larger than the air buoyancies acting on them (cf.…”

Section: Introductionmentioning

confidence: 99%

“…Numerical modelling of two-body interaction has been performed, mainly based on the potential flow theory and boundary element method, by Landweber, Chwang & Guo (1991), Guo & Chwang (1992), Korsmeyer et al (1993), Kikuchi et al (1996), Yang & Luh (1998), and Fang & Chen (2002), among others. The numerical approach has the advantage of handling general geometry, but it is inaccurate or even singular when the two bodies are in very close proximity (Tuck 1980;Guo & Chwang 1992).…”

Section: Introductionmentioning

confidence: 99%

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An analytical solution for two slender bodies of revolution translating in very close proximity

Wang

2007

J. Fluid Mech.

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The irrotational flow past two slender bodies of revolution at angles of yaw, translating in parallel paths in very close proximity, is analysed by extending the classical slender body theory. The flow far away from the two bodies is shown to be a direct problem, which is represented in terms of two line sources along their longitudinal axes, at the strengths of the variation rates of their cross-section areas. The inner flow near the two bodies is reduced to the plane flow problem of the expanding (contracting) and lateral translations of two parallel circular cylinders with different radii, which is then solved analytically using conformal mapping. Consequently, an analytical flow solution has been obtained for two arbitrary slender bodies of revolution at angles of yaw translating in close proximity. The lateral forces and yaw moments acting on the two bodies are obtained in terms of integrals along the body lengths. A comparison is made among the present model for two slender bodies in close proximity, Tuck & Newman's (1974) model for two slender bodies far apart, and VSAERO (AMI)–commercial software based on potential flow theory and the boundary element method (BEM). The attraction force of the present model agrees well with the BEM result, when the clearance, h0, is within 20% of the body length, whereas the attraction force of Tuck & Newman is much smaller than the BEM result when h0 is within 30% of the body length, but approaches the latter when h0 is about half the body length. Numerical simulations are performed for the three typical manoeuvres of two bodies: (i) a body passing a stationary body, (ii) two bodies in a meeting manoeuvre (translating in opposite directions), and (iii) two bodies in a passing manoeuvre (translating in the same direction). The analysis reveals the orders of the lateral forces and yaw moments, as well as their variation trends in terms of the manoeuvre type, velocities, sizes, angles of yaw of the two bodies, and their proximity, etc. These irrotational dynamic features are expected to provide a basic understanding of this problem and will be beneficial to further numerical and experimental studies involving additional physical effects.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An analytical solution for two slender bodies of revolution translating in very close proximity

Wang

2007

J. Fluid Mech.

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“…The hydrodynamic interaction between a three-dimensional body and an infinitely long cylinder was investigated by Guo and Chwang (1993). The hydrodynamic interaction of two vessels moving at the same speed in nearfield was considered by Yeung and Hwang (1977) applying the slender-body theory in potential flows. Theoretical predictions on sway force and yaw moment were generally high in comparison with available experimental measurements.…”

Section: 2 / B Xmentioning

confidence: 99%

“…It was found by Sun and Chwang (2001a) that the presence of a sphere generates an effect on the planar motion of the slightly distorted sphere and the initial configuration of the slightly distorted sphere has a decisive influence on the development of its subsequent rotational motion. Yang and Luh (1998) used the Lagrange equations of motion to study the unsteady ground effect on the motion of a body. They conducted numerical simulations for a prolate spheroid moving in the fore-and-aft direction at constant speed past a flat ground with a protrusion.…”

Section: A Moving Elliptic Cylindermentioning

confidence: 99%

“…Reasons for the over-prediction of the theoretical model were attributed to the viscous effect. Wang and Wahab (1971) presented a solution of the two-dimensional potential problem associated with a semisubmerged twin-cylinder performing small vertical oscillations in a free surface. Results of the added-mass and damping coefficients were presented as functions of the oscillation frequency.…”

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confidence: 99%

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