2016
Scattering of gravity waves in subcritical flows over an obstacle
Abstract: We numerically study the scattering coefficients of linear water waves on stationary flows above a localized obstacle. We compare the scattering on trans-and subcritical flows, and then focus on the latter which have been used in recent analog gravity experiments. The main difference concerns the magnitude of the mode amplification: whereas transcritical flows display a large amplification (which is generally in good agreement with the Hawking prediction), this effect is heavily suppressed in subcritical flows…
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Cited by 25 publications
(41 citation statements)
References 34 publications
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“…We see that the general behavior of | β| 2 is linear in ω. This contrasts with the case of a transcritical flow, and agrees with the results of [16,18,35]. Before analyzing this behavior in more details, we construct the mode φ in u , schematically represented in Fig.…”
Section: General Resultssupporting
confidence: 83%
“…We see that the general behavior of | β| 2 is linear in ω. This contrasts with the case of a transcritical flow, and agrees with the results of [16,18,35]. Before analyzing this behavior in more details, we construct the mode φ in u , schematically represented in Fig.…”
Section: General Resultssupporting
confidence: 83%
“…[29] The problem studied can be further generalized for waves of arbitrary length taking into account the effect of dispersion. Similar works in this direction were published recently for relatively smooth current variation in the canal with the finite-length bottom obstacles [17,18]. It is worthwhile to notice that in the dispersive case for purely gravity waves there is always one wave of negative energy for which the flow is supercritical.…”
Section: Discussionsupporting
confidence: 74%
“…Clearly, the scattering coefficients do not diverge as the frequency cancels. Hence, the expected thermal spectrum for trans-critical flow is not observed, since the scattering coefficients vanish when the angular frequency goes to zero (in accordance with the numerical and theoretical predictions for subcritical flows [37][38][39][40][41][42][43]).…”
supporting
confidence: 83%
