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a reduced model for internal waves interacting with submarine ...

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0.1<br />

0.09<br />

0.08<br />

0.07<br />

0.06<br />

0.05<br />

0.04<br />

0.03<br />

0.02<br />

0.01<br />

0<br />

0 10 20 30 40 50 60<br />

Figure 4.15: Numerical solution of the WNFM <strong>with</strong>β=0.0001,α=0.01 <strong>for</strong> the<br />

propagation of a single solitary wave.<br />

andλ = 0.3323 are selected in the solitary wave solution of Eq. (2.42); u 1 is<br />

taken to be the corresponding dispersive solution <strong>for</strong> one propagation direction,<br />

see Section 4.3.<br />

The expected behaviour of the wave is captured by the numerical method <strong>for</strong><br />

long times as shown in Fig. 4.16. The pulse propagates <strong>with</strong> an approximate<br />

velocity of 0.9884 in con<strong>for</strong>mity <strong>with</strong> its propagation velocity c=0.9961 in the<br />

Regularized ILW equation (2.42). The shape of the solitary wave is preserved <strong>for</strong><br />

long times as shown in Fig. 4.17. The error between the initial condition and the<br />

solution that returns to the original position at approximate time t=50.8545 is<br />

0.0047. Taking into account that the choice of u 1 is an approximation from the<br />

linear case (α=0), the result is satisfactory.<br />

Example 4.9. In Fig. 4.18 the fission of a single approximate solitary wave solution<br />

is simulated. As initial condition <strong>for</strong>η, the same parametersθ = π/8,<br />

a=−0.099536 andλ=0.3323 are used, while u 10 = 0. We observe two <strong>waves</strong><br />

82

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