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

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0.6<br />

0.5<br />

0.4<br />

0.3<br />

η<br />

0.2<br />

0.1<br />

0<br />

−0.1<br />

0 10 20 30 40 50 60<br />

ξ<br />

Figure 4.6: Fission of the wave. Dotted line: numerical solution <strong>for</strong> the nondispersive<br />

LFM using RK4 <strong>for</strong> t=50.2655 and N= 512,∆ξ=2l/N= 0.098175,<br />

∆t=∆ξ=0.098175, dashed line: initial condition, solid line: exact solution.<br />

ξ ∈ Π[0, 2l],<br />

⎧<br />

η t − u 1ξ = 0,<br />

⎪⎨<br />

u 1t −η ξ = √ β ρ 2<br />

ρ 1<br />

T [0,2l]<br />

[<br />

u1<br />

]<br />

ξt ,<br />

η(ξ, 0)=η 0 (ξ),<br />

⎪⎩ u 1 (ξ, 0)=u 10 (ξ).<br />

(4.9)<br />

First, let us per<strong>for</strong>m the change of variablesξ=πξ/l, t=πt/l to the standard<br />

periodic domainξ ∈ Π[0, 2π]. The time variable is modified in order to maintain<br />

the wave velocity as one <strong>for</strong> the hyperbolic regime (β=0). In these coordinates<br />

70

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