| Budget Amount *help |
¥7,600,000 (Direct Cost: ¥7,600,000)
Fiscal Year 1998: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1997: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1996: ¥3,800,000 (Direct Cost: ¥3,800,000)
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| Research Abstract |
In hull form designs of advancing bodies floating on water, predictions of hydrodynamic forces acting on them are very importnat. Especially, in the case of high speed crafts with hydrofoils and sailing boats, those predictions become very difficult, because they have lifting parts on the hull. Predictions of wave making characteristics around multi hull vessels are also difficult because of the complicated interior flow among respective hulls. Since the interior flow is different from the exterior flow in respective hulls, they must be considered lifting bodies.
As well known, Morino' s panel method is very useful to predict the hydrodynamic forces acting on lifting bodies, but the original Morino's method have no function to solve the free surface boundary value problem. For the pupose of the analysis of free suface flow, Rankine source method is recognized as one of the most effective tools. However, this method have no function to evaluate lifting effects. In the present study, Morino's panel method is extended to the problem of free surface flow around advancing bodies with lifting parts under the free surface. In similar manner, the ordinary Rankine source method must be modified to express lifting effects. For this purpose, velocity components induced by vortex lattices on the center plane of the lifting hulls are introduced into the formulation.
Numerical calculations are carried out for several examples. According to the comparison of the numerical results of these examples, it is concluded that the present suggested methods have effective roles to predict their hydrodynamic characteristics, such as wave making characteristics arouund lifting bodies, and coefficients of hydrodynamic forces and/or moments.
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