Metastability of solitary roll wave solutions of the St. Venant equations with viscosity

Abstract

We study by a combination of numerical and analytical Evans function techniques the stability of solitary wave solutions of the St. Venant equations for viscous shallow-water flow down an incline, and related models. Our main result is to exhibit examples of metastable solitary waves for the St. Venant equations, with stable point spectrum indicating coherence of the wave profile but unstable essential spectrum indicating oscillatory convective instabilities shed in its wake. We propose a mechanism based on ``dynamic spectrum'' of the wave profile, by which a wave train of solitary pulses can stabilize each other by de-amplification of convective instabilities as they pass through successive waves. We present numerical time evolution studies supporting these conclusions, which bear also on the possibility of stable periodic solutions close to the homoclinic. For the closely related viscous Jin-Xin model, by contrast, for which the essential spectrum is stable, we show using the stability index of Gardner--Zumbrun that solitary wave pulses are always exponentially unstable, possessing point spectra with positive real part.

42 pages, 9 figures

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Cited by in corpus (8)

• Nonlinear modulational stability of periodic traveling-wave solutions of the generalized Kuramoto-Sivashinsky equation
• Spectral Stability of Inviscid Roll Waves
• Stability of viscous St. Venant roll-waves: from onset to infinite-Froude number limit
• Whitham's equations for modulated roll-waves in shallow flows
• Convergence as period goes to infinity of spectra of periodic traveling waves toward essential spectra of a homoclinic limit
• Periodic-coefficient damping estimates, and stability of large-amplitude roll waves in inclined thin film flow
• Modulated wave trains in generalized Kuramoto-Sivashinksi equations
• Whitham Averaged Equations and Modulational Stability of Periodic Traveling Waves of a Hyperbolic-Parabolic Balance Law