The Proceedings Fifth International Conference on Numerical Ship Hydrodynamics (1990) / Chapter Skim
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Computations of 3D Transom Stern Flows
Computations of 3D Transom Stern Flows
Pages 581-592
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From page 581... ...
The theory and numerics of computing transom stern flows are described in detail. The special treatment of the linearized free surface boundary condition is included.
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From page 582... ...
The usual treatment of cruiser sterns is presented since the special treatment for transom sterns is similar and is an extension of the cruiser stern method. In the Rankine source panel method, a hull surface is m athem atically subdivided into hundreds of small source panels.
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From page 583... ...
3.2 Theory of the transom boundary condition As for a cruiser stern ease, a transom stern solution begins with a double model computation. The geometric model for a transom stern hull is shown in Fig.
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From page 584... ...
To simplify the analysis of transom flows in practical applications, several assumptions are made in the theory for transom stern flows. It is assumed that the transom is left open as in the double model flow computations and that the potential flow detaches from the transom at well defined locations.
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From page 585... ...
Equations 18, 19, and 20 are applied as the transom boundary conditions for the free surface calculations in the case of a dry transom. In so doing, the static pressure is forced to be atmospheric and the free surface flow is forced to leave the transom tangentially in a direction specified by the double model flow.
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From page 586... ...
The numerical model of the transom stern is shown on the right. The dashed line represents the mean water level and the solid wavy line represents the free surface computed on pane is closest to the ce nte rplane.
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From page 587... ...
measured wave pattern resistance was then compared to the wave resistance predicted by integrating the pressure on the hull using the XYZFS program version 2.0.
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From page 588... ...
The nurrnerical implementation of the free surface boundary condition involves the use of an upstream finite difference operator to eliminate upstream waves. The transom boundary condition has been used to specify the starting values for the free surface calculations in a special section behind the transom.
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From page 589... ...
12. Jenkins, D.S., "Resistance Characteristics of the High Speed Transom Stern Ship R/V ATHENA in the Bare Hull Condition, Represented by O TNSRD C Model 5365," D TNSRD C report 84/024, D TNSRD C, Bethesda, MD ~ June 1984~.
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From page 590... ...
The computed results could be further improved by using the experimentally measured sinkage and trim to reposition the hull. at, 0.6 dl Fig.A1 Comparison between calculated wave resistance and measured wave pattern resistance versus Froude number for Model 5416 (sunk and trimmed case)
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From page 591... ...
It is true that the XYZ Free Surface problem uses upstream finite difference operators to eliminate upstream propagating waves, thus satisfying the radiation condition numerically. However, we have not experienced the point-to-point oscillations of the source strength near the down stream boundary as referred to by Mr.
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