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Minimal model for tidal bore revisited

Research output: Contribution to journalArticle

Original languageEnglish
Article number073021
Number of pages10
JournalNew Journal of Physics
Volume21
Early online date19 Jun 2019
DOIs
DateAccepted/In press - 19 Jun 2019
DateE-pub ahead of print - 19 Jun 2019
DatePublished (current) - 8 Jul 2019

Abstract

This develops a recent analysis of gentle undular tidal bores (2018 New J. Phys. 20 053066) and corrects an error. The simplest linear-wave superposition, of monochromatic waves propagating according to the shallow-water dispersion relation, leads to a family of profiles satisfying natural tidal bore boundary conditions, involving initial smoothed steps with different shapes. These profiles can be uniformly approximated to high accuracy in terms of the integral of an Airy function with deformed argument. For the long times corresponding to realistic bores, the profiles condense asymptotically onto the previously obtained integral-Airy function with linear argument: As the bore propagates, it forgets the shape of the initial step. The integral-Airy profile expands slowly, as the cube root of time, rather than advancing rigidly. This 'minimal model' leads to simple formulas for the main properties of the profile: Amplitude, maximum slope, 'wavelength', and steepness; and an assumption about energy loss suggests how the bore weakens as it propagates.

    Research areas

  • Airy function, Asymptotic, Caustic, Hamiltonian, Nonlinearity, Wave

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    Rights statement: This is the final published version of the article (version of record). It first appeared online via IOP Publishing at https://iopscience.iop.org/article/10.1088/1367-2630/ab2b19 . Please refer to any applicable terms of use of the publisher.

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