Wave Motion最新文献

Rogue waves can appear in various physical scenarios, including those described by coupled equations. Volumes for rogue wave pairs of coupled equations can be defined using intensities of each individual rogue wave, or via a combined definition for the pair. We consider Manakov equations supporting bright-dark rogue wave pairs, and various other equations. This extends the rogue wave ‘volume’ concept in a useful way and allows for characterization of these pairs by using a single number. If the volume is found from experimental data, e.g. in a water tank, then the values of internal solution parameters can be deduced.

In this paper, we develop another approach to construct the multi-soliton solutions of a two-component Camassa–Holm equation in terms of Wronskians with help of a reciprocal transformation and a gauge transformation. Its kink solution, loop solution and smooth soliton solution are presented. Then with the non-trivial limiting procedure, the solution of Camassa–Holm equation is also derived from that of two-component Camassa–Holm equation.

In this paper, we employ a combination of analytical and numerical techniques to investigate the dynamics of lattice envelope vector soliton solutions propagating within a one-dimensional chain of flexible mechanical metamaterial. To model the system, we formulate discrete equations that describe the longitudinal and rotational displacements of each individual rigid unit mass using a lump element approach. By applying the multiple-scales method in the context of a semi-discrete approximation, we derive an effective nonlinear Schrödinger equation that characterizes the evolution of rotational and slowly varying envelope waves from the aforementioned discrete motion equations. We thus show that this flexible mechanical metamaterial chain supports envelope vector solitons where the rotational component has the form of either a bright or a dark soliton. In addition, due to nonlinear coupling, the longitudinal displacement displays kink-like profiles thus forming the 2-components vector soliton. These findings, which include specific vector envelope solutions, enrich our knowledge on the nonlinear wave solutions supported by flexible mechanical metamaterials and open new possibilities for the control of nonlinear waves and vibrations.

In the current work, we consider particle trajectories beneath traveling soliton solutions described by the Kadomtsev–Petiviashvili-II (KP-II) equation, which is a model for small-amplitude water waves in shallow water. The KP-II equation has a large number of exact solutions describing crossing line solitons. Here, we describe the particle drift induced by the single line soliton and various two- and three-soliton solutions on a two-dimensional horizontal domain.

First, the derivation of the KP-II equation is used to exhibit expressions for the three components of the fluid velocity vector induced by a surface wave profile given by the KP-II equation. These velocity components can be used to specify a coupled system of ordinary differential equations (ODEs) which describe the motion of a fluid particle. Given an initial position inside the fluid for a specific particle, as well as continuously providing time-dependent values for the surface deflection, the ODE system can be solved numerically to find the particle path induced by the passage of a wave. A special numerical integration grid tracking the particle is used to handle integral terms occurring in the fluid velocity expressions.

In this paper, we construct the high-order breather and interaction solutions of the $(3+1)$-dimensional Mel’nikov equation using the KP hierarchy reduction approach and express them in a concise determinant form. Our solutions show that the two breathers, two periodic waves, and the hybrid mode of the breather and periodic wave are all mutually parallel. Furthermore, by examining the long wave limit of the periodic wave solutions, a variety of rational solutions (lumps) and mixed solutions are obtained. Notably, the interaction between the lump and breather is found to be elastic. These novel results provide deeper insights into the interactions among different solution types.

Breathing discrete vortices are obtained as numerically exact and generally quasiperiodic, localized solutions to the discrete nonlinear Schrödinger equation with cubic (Kerr) on-site nonlinearity, on a two-dimensional square lattice with nearest-neighbor couplings. We identify and analyze three different types of solutions characterized by circulating currents and time-periodically oscillating intensity distributions, two of which have been discussed in earlier works while the third being, to our knowledge, presented here for the first time. (i) A vortex-breather, constructed from the anticontinuous limit as a superposition of a single-site breather and a discrete vortex surrounding it, where the breather and vortex are oscillating at different frequencies. (ii) A charge-flipping vortex, constructed from an anticontinuous solution with an even number of sites on a closed loop, with alternating sites oscillating at different frequencies. (iii) A breathing vortex, constructed by continuation of a non-resonating linear internal eigenmode of a stationary discrete vortex. We illustrate by examples, using numerical Floquet analysis for solutions obtained from a Newton scheme, that linearly stable solutions exist from all three categories, at sufficiently strong discreteness.

The paper deals with the propagation of a stochastic wave in an elastic medium using the example of a seismic wave in a ground medium. Identification of subsoil parameters is never exact or complete which justifies the use of random field models or random variable models for input data; thus, the response of the subsoil is also random. In this paper and in the context of random variables, the focus is on a sensitivity analysis addressing the question of how the uncertainty of the input data (subgrade parameters) influences the obtained results (displacements). Two different methods of stochastic analysis are presented—the intrusive polynomial chaos approach supported by the Galerkin projection and Monte Carlo simulation—and compared by using an example of wave propagation in the elastic half-plane. Consistency in the results of both approaches has been achieved; however, the calculation efficiencies differ. The advantages and disadvantages of both approaches are discussed. The upper subsoil layer influences the variances of the random solutions much more than does the lower layer.

Ray tracing is crucial for analyzing wave behaviors in diverse applications. This study presents an approach that extends beyond traditional methods, which typically involve solving second–order differential equations to determine ray trajectories. Leveraging classical momentum–impulse relations and the system’s Lagrangian, we establish a set of intuitive first integrals that circumvent the need for direct differential solutions, paving the way for optimization techniques. Our method employs the “shooting method” a technique for approximating solutions to differential equations by iteratively applying initial conditions. We introduce a novel momentum cost function that streamlines angle determination in anisotropic environments, a significant departure from conventional practices. Numerical validations demonstrate the robustness of our approach, confirming its efficacy in handling both sharp and gradual refractive index changes with high accuracy. The results also highlight the computational intensity required in anisotropic conditions, suggesting potential areas for efficiency improvements. This groundwork not only enhances current understanding but also opens avenues for future research into more complex media.

Numerical and experimental investigations were conducted using vegetation models with varying leaf thicknesses, meadow lengths, and friction coefficients, to evaluate the efficacy of vegetation in reducing wave transmission under different wave heights, periods, and submergence conditions. A modified shallow-water model considering the effect of friction coefficient as a function of several wave characteristics was developed. The model was solved numerically using a staggered finite volume model. The numerical model was validated using experimental data. Good agreement was observed between the experimental and numerical results, particularly in terms of the wave amplitude and phase. A genetic algorithm was used to derive empirical formulas using the friction coefficient as a function of different vegetation and wave parameters. The results showed that increasing the leaf thickness increased the friction coefficient and reduced the wave transmission. However, increasing the meadow length had a greater effect than increasing the leaf thickness. An emergent meadow covered the entire water column. Hence, it yielded the highest friction coefficient and wave transmission reduction among all tested submergence conditions. A sensitivity analysis was performed to assess the effects of the wave height, wave period, and leaf thickness. The results indicated that the maximum reduction in wave transmission was achieved under emergent conditions with high wave energies, short wavelengths, and thick leaves. This was attributed to enhanced wave–vegetation interaction, wave breaking, and energy dissipation. The observations of this study will aid coastal engineers in selecting the optimal leaf height, leaf thickness, and meadow length to achieve the desired reduction in wave transmission.

The note addresses a qualitative difference between shallow (vertically confined) and deep (vertically non-confined) fluid geometries for stationary internal solitary waves. It is shown that in a deep fluid, the propagation velocity of large amplitude wave (with a vortex inside) is greater than the velocity predicted by small but finite amplitude theory, known as the Benjamin-Ono model. This effect has been found both asymptotically and experimentally. For the case of a shallow fluid, the situation is qualitatively different. The speed of a wave with vortex inside is smaller than that predicted by the Korteweg-de Vries theory. The reported observation could distinguish wave motions in shallow (confined) and deep (non-confined) geometries and seems to be important in a variety of applications.