Particle acceleration in localized nonlinear wave fields

1998 ◽  
Vol 21 (4) ◽  
pp. 619-628 ◽  
Author(s):  
Rudolf A Treumann
2004 ◽  
Vol 11 (3) ◽  
pp. 281-293
Author(s):  
V. Goncharov ◽  
V. Pavlov

Abstract. The problem of the null-modes existence and some particularities of their interaction with nonlinear vortex-wave-like structures is discussed. We show that the null-modes are fundamental elements of nonlinear wave fields. The conditions under which null-modes can manifest themselves are elucidated. The Rossby-Hasegawa-Mima (RHM) model is used for the illustration of features of null-modes-waves interactions.


2005 ◽  
Vol 12 (5) ◽  
pp. 671-689 ◽  
Author(s):  
D. Chalikov

Abstract. A numerical model for long-term simulation of gravity surface waves is described. The model is designed as a component of a coupled Wave Boundary Layer/Sea Waves model, for investigation of small-scale dynamic and thermodynamic interactions between the ocean and atmosphere. Statistical properties of nonlinear wave fields are investigated on a basis of direct hydrodynamical modeling of 1-D potential periodic surface waves. The method is based on a nonstationary conformal surface-following coordinate transformation; this approach reduces the principal equations of potential waves to two simple evolutionary equations for the elevation and the velocity potential on the surface. The numerical scheme is based on a Fourier transform method. High accuracy was confirmed by validation of the nonstationary model against known solutions, and by comparison between the results obtained with different resolutions in the horizontal. The scheme allows reproduction of the propagation of steep Stokes waves for thousands of periods with very high accuracy. The method here developed is applied to simulation of the evolution of wave fields with large number of modes for many periods of dominant waves. The statistical characteristics of nonlinear wave fields for waves of different steepness were investigated: spectra, curtosis and skewness, dispersion relation, life time. The prime result is that wave field may be presented as a superposition of linear waves is valid only for small amplitudes. It is shown as well, that nonlinear wave fields are rather a superposition of Stokes waves not linear waves. Potential flow, free surface, conformal mapping, numerical modeling of waves, gravity waves, Stokes waves, breaking waves, freak waves, wind-wave interaction.


1978 ◽  
Vol 21 (8) ◽  
pp. 1448
Author(s):  
Bruce J. West
Keyword(s):  

Author(s):  
Weiguang Bao ◽  
Takeshi Kinoshita ◽  
Motoki Yoshida

The problem of a circular cylinder array slowly oscillating in both diffraction and radiation wave fields is considered in the present work. As a result of the interaction between the wave fields and the low-frequency motion, nonlinear wave loads may be separated into the so-called wave-drift added mass and damping. They are force components proportional to the square of the wave amplitude but in phase of the acceleration and velocity of the low-frequency motion respectively. The frequency of the slow oscillation is assumed to be much smaller than the wave frequency. Perturbation expansion based on two time scales and two small parameters is performed to the order to include the effects of the acceleration of the low-frequency motion. Solutions to these higher order potentials are suggested in the present work. Wave loads including the wave drift added mass and damping are evaluated by the integration of the hydrodynamic pressure over the instantaneous wetted body surface.


1992 ◽  
Vol 128 ◽  
pp. 109-111
Author(s):  
K. O. Thielheim

A magnet rotating in vacuo with its vector of angular velocity ω perpendicular to its vector of magnetic dipole moment μ is able to act as a particle accelerator. The dynamic features involved may be relevant for the understanding of rotating magnetized neutron stars as cosmic accelerators (Thielheim 1989) and may be useful for the designing of new mechanisms for accelerating devices.


1975 ◽  
Vol 18 (10) ◽  
pp. 1084-1097 ◽  
Author(s):  
V. E. Zakharov ◽  
V. S. L'vov
Keyword(s):  

2018 ◽  
Vol 838 ◽  
pp. 544-572 ◽  
Author(s):  
Yusheng Qi ◽  
Guangyu Wu ◽  
Yuming Liu ◽  
Moo-Hyun Kim ◽  
Dick K. P. Yue

We develop and validate a high-order reconstruction (HOR) method for the phase-resolved reconstruction of a nonlinear wave field given a set of wave measurements. HOR optimizes the amplitude and phase of $L$ free wave components of the wave field, accounting for nonlinear wave interactions up to order $M$ in the evolution, to obtain a wave field that minimizes the reconstruction error between the reconstructed wave field and the given measurements. For a given reconstruction tolerance, $L$ and $M$ are provided in the HOR scheme itself. To demonstrate the validity and efficacy of HOR, we perform extensive tests of general two- and three-dimensional wave fields specified by theoretical Stokes waves, nonlinear simulations and physical wave fields in tank experiments which we conduct. The necessary $L$, for general broad-banded wave fields, is shown to be substantially less than the free and locked modes needed for the nonlinear evolution. We find that, even for relatively small wave steepness, the inclusion of high-order effects in HOR is important for prediction of wave kinematics not in the measurements. For all the cases we consider, HOR converges to the underlying wave field within a nonlinear spatial-temporal predictable zone ${\mathcal{P}}_{NL}$ which depends on the measurements and wave nonlinearity. For infinitesimal waves, ${\mathcal{P}}_{NL}$ matches the linear predictable zone ${\mathcal{P}}_{L}$, verifying the analytic solution presented in Qi et al. (Wave Motion, vol. 77, 2018, pp. 195–213). With increasing wave nonlinearity, we find that ${\mathcal{P}}_{NL}$ contains and is generally greater than ${\mathcal{P}}_{L}$. Thus ${\mathcal{P}}_{L}$ provides a (conservative) estimate of ${\mathcal{P}}_{NL}$ when the underlying wave field is not known.


Author(s):  
Fabrice Poirion ◽  
Michel Benoit

The aim of this work is to present a method for constructing simulations of correlated trajectories of sea surface vertical displacement at different locations. It can also be used in order to construct a stochastic model for a single wave with given physical characteristics.


1992 ◽  
Vol 82 (2) ◽  
pp. 1134-1143
Author(s):  
How-Wei Chen ◽  
George A. McMechan

Abstract By using the elastodynamic equations rather than wave equations for seismogram synthesis, multi-attribute wave fields can be computed in a single execution of one program. In the present implementation, for 2-D models, the wave fields and seismograms produced include any or all of the following: two components of each of particle acceleration, particle velocity, and particle displacement; two components of normal strain; shear strain; two components of normal stress; shear stress; and the dilatation and curl of the particle displacement. If flexible source and receiver configurations are also included, a single piece of software can be used for most seismic modeling applications. This significantly reduces the need for development and maintenance of separate programs. The algorithm is illustrated using waves synthesized for an explosive source in a layered medium. Snapshots and seismograms at both surface and borehole arrays are presented.


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