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Research Article

The instability of stratified flows at large Richardson numbers

Andrew J. Madja and Michael Shefter
PNAS July 7, 1998 95 (14) 7850-7853; https://doi.org/10.1073/pnas.95.14.7850
Andrew J. Madja
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Michael Shefter
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  1. Contributed by Andrew J. Madja

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Abstract

In contrast to conventional expectations based on the stability of steady shear flows, elementary time-periodic stratified flows that are unstable at arbitrarily large Richardson numbers are presented here. The fundamental instability is a parametric one with twice the period of the basic state. This instability spontaneously generates local shears on buoyancy time scales near a specific angle of inclination that saturates into a localized regime of strong mixing with density overturning. We speculate that such instabilities may contribute significantly to the step-like microstructure often observed in buoyancy measurements in the ocean.

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      • Accepted May 4, 1998.
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      The instability of stratified flows at large Richardson numbers
      Andrew J. Madja, Michael Shefter
      Proceedings of the National Academy of Sciences Jul 1998, 95 (14) 7850-7853; DOI: 10.1073/pnas.95.14.7850

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      The instability of stratified flows at large Richardson numbers
      Andrew J. Madja, Michael Shefter
      Proceedings of the National Academy of Sciences Jul 1998, 95 (14) 7850-7853; DOI: 10.1073/pnas.95.14.7850
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