Twenty-First Symposium on Naval Hydrodynamics (1997) / Chapter Skim
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Numerical Simulation of Three-Dimensional Breaking Waves About Ships
Numerical Simulation of Three-Dimensional Breaking Waves About Ships
Pages 506-519
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From page 506... ...
Hence the clarification of the breaking wave phenomenon is of essential importance for the progress in both marine structural dynamics and ship hydrodynamics represented by hull form design. Some numerical simulations for the strongly nonlinear waves have been carried out by many researchers.
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From page 507... ...
NUMERICAL METHOD Finite-difference Method For the time derivative of velocity forward differencing is used and second-order centered differencing is for the space derivatives excluding the convective terms for which third-order upwind differencing is used. Finite-volume method The WISDAM-VI method employs the coordinate system that is fitted to the body boundary but not to the free surface, so that the boundary layer around the body of arbitrary form and large freesurface deformation is simultaneously simulated.
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From page 508... ...
However, it is demonstrated in the subsequent section that the degree of accuracy can be raised to a sufficient level in case a higher-order differencing scheme such as third-order upwind scheme used here is employed in a fine grid system. After determining the interface location the dynamic free surface condition is implemented by the so-called "irregular star" techniquet16]
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From page 509... ...
A typical plane vertical and parallel to the diFREE SURFACE SHOCK WAVE ABOUT A WEDGE MODEL The nonlinear features of ship waves in the near field had been noticed in the 1970s and the detailed structure and mechanism of nonlinear bow waves are experimentally investigated by Miyata et 509
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From page 510... ...
However, since the TUMMACVIII method employs the rectangular grid system, it can not accurately simulate the viscous phenomena such as growth and separation of the boundary layer, which contributes to the most significant part of resistance of a ship of practical hull forms. In a practical sence, the simultaneous simulation of nonlinear wave system and viscous flow around ships would give very useful information to hull form designers.
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From page 511... ...
and Miyata, H., "Elucidation of the structure of free surface shock waves about a wedge model by finite-difference method," Journal of The Society of Naval Architects of Japan, Vol.
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From page 512... ...
Figure 2: Difference of the vertical distributions of density function due to the time increment in case of 3rd order upwind scheme.
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From page 513... ...
. Figure 3: Wave profiles by calculations in the wave-proceeding direction for three wave periods, T=O.9, 1.2 and 1.5sec.
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From page 514... ...
<' ~ 18.0 19.0 ...... Figure 4: Time variations of the wave elevation by calculations and experiments for three wave periods T=0.9, 1.2 and 1.5sec.
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From page 515... ...
T= 1.472(soc)
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From page 516... ...
1 1.932 1 2.392 2 ? ~92 l 1.564 1 2.024 l 2.484 1.656 1 2.116 1 2.576 1.748 1 2.208 1 1.840 =: ~ 2.3 Figure 6: Time-sequential contour of the magnitude of Lamb Vector on the plane vertical and parallel to the direction of uniform stream.
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Bulk carrier model: M55FOAO (Fn = 0.18) Figure 9: Perspective view of computed waves 517
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~ ~ /~ /.,'" / -- -- ~_ -) In Computed Figure 11: Comparison of the bow awe contour map far the VLCC model SR196C (Contour interval is x 10-~, an = 0.16)
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From page 519... ...
S.S.5 S.S. 2 1J2 Figure 12: Comparison of the bow wave contour Figure 13: Distribution of total head loss (contour map for the bulk carrier model M55FOAO (Wave interval is 5% of total head of the uniform flow, height is nondimensionalized by the head of uniform SR196C En = 0.16)
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