Search arXivSearch

arXiv · 1704.08948

Interaction of Tollmien-Schlichting Waves in the Air with the Sea Surface

Abstract

Linear stability of fully developed flows of air over water is carried out in order to study non-linear effects in the generation of solitons by wind. A linear stability analysis of the basic flow is made and the conditions at which solitons first begin to grow is determined. Then, following [10], the non-linear stability of the flow is examined and the quintic non-linear Schrödinger equation is derived for the amplitude of disturbances. The coefficients of the non-linear Schrödinger equation are calculated from the eigenvalue problem which determines the stability of air-water interface. An asymptotic and a numerical stability analysis is carried out to determine the neutrally stable flow conditions for air-sea interface. Four different profiles are considered for the airflow blowing over the surface of the sea, namely, plane Couette flow (pCf), plane Poiseuille flow (pPf), laminar and turbulent boundary layer (L,TBL) profiles. For each of the above cases the shear flow counterpart in the water is assumed to be a pPf. It is shown that the above amplitude equation produces `snake' solitons [9] for pCf, pPf and LBL profiles, with striking similarities. On the other hand, for TBL we observe a very violent surface motion. For cases of pCf and LBL remarkable similarity is observed with observations made at sea. We conclude that the effect of nonlinearity in the airflow over the sea surface is much larger than nonlinear interactions in the water, and hence it is not possible to decouple the motion in the air and the water for finite amplitude wind-wave interactions, particularly in the case of wind-generated solitons in shallow waters.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Shahrdad G. Sajjadi, Harihar Khanal. 2017-04-26. Interaction of Tollmien-Schlichting Waves in the Air with the Sea Surface. https://arxiv.org/abs/1704.08948

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

Self-similar vector solitons for the coupled higher-order nonlinear Schrodinger equations in inhomogeneous optical fibers

We prove the existence of two kinds of self-similar vector solitons in an inhomogeneous optical fiber medium, where light propagation is governed by a pair of coupled higher-order nonlinear Schrodinger equations with varying second- and third-order dispersions, self- and cross-phase modulation non linearities, self-steepening, and linear gain/loss effects. The newly found self-similar waves comprise bright-W-shaped and kink-antikink waveforms with nonvanishing amplitudes. As a practical exam ple, we discuss the propagation dynamics of these soliton structures in a periodically distributed fiber system as well as an exponential dispersion-decreasing fiber. The results demonstrate that the parameter functions of gain/loss and third-order dispersion serve as a key factor in determining the nonlinear dynamics of self-similar vector solitons. In particular, we find that precise control over the shape and dynamic evolution of self-similar pulses can be achieved through a proper choice of the distributed third-order dispersion parameter, while the gain/loss coefficient controls their intensity.

nlin.PS

Fast Synergetic Simulation to Study Slow Evolution of Soliton Patterns in Optical Resonators

Complex patterns in physical and biological systems often emerge through slow collective dynamics governed by a small number of key variables. In nonlinear optical resonators, dissipative Kerr solitons provide an important example, where interactions between well-separated solitons can evolve over timescales far longer than the characteristic loss and gain timescales. Direct numerical simulation of these dynamics is challenging because stiffness forces conventional methods to resolve many rapidly damped degrees-of-freedom with very small time steps. We present a numerical scheme, the synergetic method, that eliminates these rapidly damped degrees-of-freedom and retains the slowly evolving modes, enabling time steps many orders of magnitude larger than those used in conventional approaches. Applied to soliton molecules in driven Kerr cavities, the method achieves speedups of $10^3$ to $10^5$ while capturing dynamics on laboratory timescales. We use it to model the full interaction dynamics of a three-soliton molecule and the evolution of an eight-soliton molecule. The approach provides an efficient framework for studying slow pattern formation in nonlinear systems with widely separated timescales.

nlin.PS

Breathers in solitonic room-temperature superlattice-induced superfluorescence in quasi-2D perovskites

Recently, a soliton mechanism for room-temperature superfluorescence in thin perovskite films has been proposed, with a fundamental soliton predicted to remain stable under LO phonon--exciton interactions. At the same time, superlattice architectures offer a route to enhancing superfluorescence in perovskites. Motivated by recent observations of room-temperature superfluorescence in periodic superlattices of quasi-2D metal-halide perovskites, we extend the 2D nonlocal nonlinear Schr\"odinger equation describing Wannier exciton--LO phonon interactions to superlattice structures, obtaining a 3D nonlocal nonlinear Schr\"odinger equation. We show that interlayer tunnelling gives rise to breather dynamics corresponding to a stable fundamental soliton in mixed coordinate--momentum space, with the coordinate parallel to the layers and the momentum perpendicular to them. The breather dynamics originate from miniband formation, which induces a momentum-dependent phase modulation of the soliton. In the absence of interlayer tunnelling, the breather dynamics disappear and the soliton becomes stationary. These results establish a direct connection between interlayer tunnelling, miniband formation and soliton dynamics, suggesting that breather behavior can provide a signature of interlayer tunnelling in quasi-2D perovskite superlattices.

nlin.PS