Fig.3 Convergence of heave added mass for the plate of L/B = 5
Fig.4 Convergence of heave damping coefficient for the plate of L/B = 5
Excellent agreement of this order was also found in the Haskind relation and for other numbers of panels.
This fact implies that the numerical check based on the energy-conservation principle may be not sufficient to ensure the accuracy of numerical results.
Figure 5 shows the amplitude of wave-exciting forces, which were computed with sufficient numbers of panels satisfying NX > 0.8 * L/λ for converged solutions, suggested from Figs.3 and 4. Not only the conventional heave force as a rigid-body motion(ζj = u0(x)v0(y) in Table 1), but also two other results as specified elastic mode shapes (ζj = u2(x)v0(y) and u2(x)v2(y) in Table 1) are shown.
In the region of short wavelengths, the amplitude is
obviously small. However, in this region, precise evaluation of the exciting force becomes crucial, since a number of resonant behaviors may exist due to elastic mode vibrations. The amplitude variation with respect to L/λ in Fig.5 is not small, and this suggests that we will have to perform computations of elastic responses for dense values of L/λ.
Table 3 Relative numerical error in the energy conservation principle, listed in percentage
(NX = 40, NY =8, L/λ = 45)
Fig.5 Wave-exciting force in heave mode of the plate of L/B = 5
Fig.6 Pressure distribution in the diffraction problem (L/λ = 10, β = 30°)
