The Weakly Nonlinear Theory

2009 ◽  
pp. 99-114
Author(s):  
Andreas Shalchi
Keyword(s):  
Nonlinear Theory ◽  
Weakly Nonlinear ◽  
Weakly Nonlinear Theory

scholarly journals Weakly nonlinear theory and sea state bias estimations

1999 ◽  
Vol 104 (C4) ◽  
pp. 7641-7647 ◽  
Author(s):  
Tanos Elfouhaily ◽  
Donald Thompson ◽  
Douglas Vandemark ◽  
Bertrand Chapron
Keyword(s):  
Nonlinear Theory ◽  
Sea State ◽  
Weakly Nonlinear ◽  
Weakly Nonlinear Theory ◽  
Sea State Bias

scholarly journals “Extraordinary” modulation instability in optics and hydrodynamics

2021 ◽  
Vol 118 (14) ◽  
pp. e2019348118
Author(s):  
Guillaume Vanderhaegen ◽  
Corentin Naveau ◽  
Pascal Szriftgiser ◽  
Alexandre Kudlinski ◽  
Matteo Conforti ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Stability Analysis ◽  
Linear Stability ◽  
Nonlinear Theory ◽  
Linear Stability Analysis ◽  
Water Waves ◽  
Modulation Instability ◽  
Nonlinear Effects ◽  
Weakly Nonlinear ◽  
Weakly Nonlinear Theory

The classical theory of modulation instability (MI) attributed to Bespalov–Talanov in optics and Benjamin–Feir for water waves is just a linear approximation of nonlinear effects and has limitations that have been corrected using the exact weakly nonlinear theory of wave propagation. We report results of experiments in both optics and hydrodynamics, which are in excellent agreement with nonlinear theory. These observations clearly demonstrate that MI has a wider band of unstable frequencies than predicted by the linear stability analysis. The range of areas where the nonlinear theory of MI can be applied is actually much larger than considered here.

Extended weakly nonlinear theory of planar nematic convection

1999 ◽  
Vol 59 (2) ◽  
pp. 1747-1769 ◽  
Author(s):  
Emmanuel Plaut ◽  
Werner Pesch
Keyword(s):  
Nonlinear Theory ◽  
Weakly Nonlinear ◽  
Weakly Nonlinear Theory

On the instability of a three-dimensional attachment-line boundary layer: weakly nonlinear theory and a numerical approach

1986 ◽  
Vol 163 ◽  
pp. 257-282 ◽  
Author(s):  
Philip Hall ◽  
Mujeeb R. Malik
Keyword(s):  
Boundary Layer ◽  
Nonlinear Theory ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Finite Amplitude ◽  
Lower Branch ◽  
Weakly Nonlinear ◽  
Weakly Nonlinear Theory ◽  
Attachment Line

The instability of a three-dimensional attachment-line boundary layer is considered in the nonlinear regime. Using weakly nonlinear theory, it is found that, apart from a small interval near the (linear) critical Reynolds number, finite-amplitude solutions bifurcate subcritically from the upper branch of the neutral curve. The time-dependent Navier–Stokes equations for the attachment-line flow have been solved using a Fourier–Chebyshev spectral method and the subcritical instability is found at wavenumbers that correspond to the upper branch. Both the theory and the numerical calculations show the existence of supercritical finite-amplitude (equilibrium) states near the lower branch which explains why the observed flow exhibits a preference for the lower branch modes. The effect of blowing and suction on nonlinear stability of the attachment-line boundary layer is also investigated.

scholarly journals On the strength of the weakly nonlinear theory for surface gravity waves

2016 ◽  
Vol 810 ◽  
pp. 1-4 ◽  
Author(s):  
Michael Stiassnie
Keyword(s):  
Gravity Waves ◽  
Nonlinear Theory ◽  
Mathematical Formulation ◽  
Wave Theory ◽  
Quantitative Agreement ◽  
Surface Gravity ◽  
Weakly Nonlinear ◽  
Surface Gravity Waves ◽  
Weakly Nonlinear Theory ◽  
Wave Basin

Recently, Bonnefoy et al. (J. Fluid Mech., vol. 805, 2016, R3) studied the resonant interaction of oblique surface gravity waves in a large $50~\text{m}\times 30~\text{m}\times 5~\text{m}$ wave basin. Their experimental results are in excellent quantitative agreement with predictions of the weakly nonlinear wave theory, and provide additional evidence to the strength of this widely used mathematical formulation. In this article, the reader is introduced to the many facets of the weakly nonlinear theory for surface gravity waves, and to its current and possible future applications, deterministic as well as stochastic.

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