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

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The AM4 scheme used is:<br />

η n+1<br />

j<br />

V n+1<br />

j<br />

=η n j + ∆t ( 251E<br />

n+1<br />

j + 646E n j<br />

720<br />

− 264En−1 j + 106E n−2<br />

j<br />

= V n j+ ∆t ( 251F<br />

n+1<br />

j + 646F n j<br />

720<br />

− 264Fn−1 j + 106F n−2<br />

j<br />

− 19E n−3 )<br />

j ,<br />

− 19F n−3 )<br />

j .<br />

To initialize both predictor-corrector schemes, the RK4 described above is<br />

employed.<br />

4.3 Flat bottom experiments<br />

Example 4.1. We first consider the LFM <strong>for</strong> the non dispersive caseβ=0,<br />

⎧<br />

⎪⎨ η t = u 1ξ ,<br />

⎪⎩ u 1t =η ξ .<br />

(4.8)<br />

This is just the bidirectional wave equation <strong>for</strong>η<br />

η tt −η ξξ = 0<br />

<strong>with</strong> initial contidions<br />

η(ξ, 0)=η 0 (ξ),<br />

⎧⎪⎨⎪⎩<br />

η t (ξ, 0)=u 10ξ (ξ).<br />

This <strong>model</strong> (whose exact solution is well known) is useful <strong>for</strong> validating and comparing<br />

the numerical schemes, since it is more demanding than the dispersive<br />

<strong>model</strong>s regarding numerical stability, as we commented in the previous Section.<br />

66

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