Lastly, an example of the pressure distribution in the diffraction problem is shown in Fig. 6, which is for L/λ = 10 and β = 30 degrees. (The y-axis is stretched, although the actual ratio is L/B = 5.) We can see that the pressure is almost zero inside and lee side of the plate, and that large variation occurs along the rim of weather side of the plate. This variation pattern is found to be the same as the incident wave.
6. CONCLUSIONS
This paper presents a new calculation scheme for the pressure distribution method, determining directly the pressure acting on the bottom of a very large and shallow-draft floating structure.
The scheme utilizes bi-cubic B-spline functions for representing the unknown pressures, and employs a Galerkin method for converting the integral equation into algebraic simultaneous equations. As a result, the scheme was confirmed to be effective particularly for short wavelengths, in the sense of good accuracy with fewer unknowns and relatively less computation time.
Accuracy of all numerical results were checked by the Haskind relation and the energy-conservation principle, and the relative error was found to be very small. Even in this case, however, a convergence test revealed that the results may not be fully converged to the values when the number of panels was increased.
Satisfactory results were obtained for short wavelengths up to L/λ = 50, with feasible computation time and numbers of unknowns for routine use.
REFERENCES
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2) Ikoma, T. et al.: Hydroelastic Responses of Very Large and Shallow Draft Floating Structures, Proc. of 13th Ocean Engineering Symposium, Soc. of Nay. Arch. of Japan, (1995), pp.185-192
3) Yago, K.: Forced Oscillation Test of Flexible Floating Structure and Hydrodynamic Pressure Distributions, Proc. of 13th Ocean Engineering Symposium, Soc. of Nay. Arch. of Japan, (1995), pp.313-320
4) Newman, J. N.: Wave Effects on Deformable Bodies, Appl. Ocean Res., Vol.16 (1994), pp.47-59
5) Wu, C. et al.: An Eigenfunction Expansion-Matching Method for Analyzing the Wave-Induced Responses of an Elastic Floating Plate, Appl. Ocean Res., Vol.17 (1995), pp.313-310
6) Sakurai, A. et al.: Spline Functions and Applications: Chapter 6, Tokyo Denki University Press, (1982), pp.88-145
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