Propagation Of Solitary Waves Research Articles

A hybrid method combining ISPH with graph neural network for simulating free-surface flows

The incompressible Smoothed Particle Hydrodynamics (ISPH) is a popular Lagrangian Particle method. In the conventional ISPH method for simulating free-surface flows, the pressure-projection phase, which solves the pressure Poisson's equation (PPE), is the most time-consuming. In this paper, we propose a novel hybrid method by combining the graph neural network (GNN) with the ISPH for modelling the free-surface flows. In the new hybrid method, the graph neural network (GNN) is employed to replace solving the PPE for pressure in the conventional ISPH. To the best of knowledge of the authors, this is the first attempt to combine the GNN with ISPH model in a Lagrangian formulation. The performance of the hybrid method will be evaluated by comparing its results with experimental data, analytical solution or numerical results from other methods for three benchmark test cases: dam breaking, sloshing wave and solitary wave propagation. In addition, the potential of generalization of the hybrid method will be studied by applying it with the GNN model trained on data for relatively simple cases to simulate more complex cases. It will be demonstrated that the hybrid method does not only give satisfactory results, but also shows good potential of generalization. In addition, the new method will be demonstrated to require the computation time which can be 80 times less than the conventional ISPH for estimating pressure for cases with a large number of particles that is usually needed in the practical free-surface flows simulation using ISPH.

Partial dam-break wave characteristics due to partial gate opening

Understanding how to predict the characteristic height of a dam-break wave is crucial for effective risk management in dam-break scenarios. This study introduces an experimental framework to simulate partial dam-break waves triggered by partial gate openings. We conducted numerous experiments to explore how different factors, including water-level differences (hi), reservoir widths (L), dam-break openings (e), and submerged depths (hw) influence the characteristic heights of the main-wave peak (h1c), subwave peak (h2c), and main-wave trough (h1t). Our analysis led to the development of an equation for predicting h1c. Furthermore, we compared the partial dam-break wave profile with the theoretical profile of a solitary wave, identifying optimal conditions for solitary wave generation and examining the velocity characteristics of partial dam-break waves. The results reveal that: (1) h1c, h2c, and h1t have positive correlations with hi and L, but negative correlations with e and hw; (2) notably, the main-wave pre-peak profile aligns more closely with the solitary wave theory; and (3) the solitary wave theory accurately predicts the main-wave peak velocity. This study enhances our understanding of wave characteristic evolution during partial dam-breaks and can be used for validation in numerical simulations.

Application of fluctuations in the sound field in inversion of internal solitary wave phase speed

Internal solitary waves propagation perturbing the sound velocity field, causes fluctuations in the sound field. This paper proposes to process the sound pressure data by the Product of the Slope and the even square of the Difference between two points of the acoustic parameter-time curve (PSD). The PSD processed data are processed to time-frequency analysis to extract the frequencies of the fluctuations in sound field. In this paper, numerical simulations and laboratory experiments are carried out on the process of internal solitary wave propagation in the sound field, and the characteristics of the sound field perturbation by internal solitary waves of different amplitudes are investigated. Results are both showing that the method can extract the dominant frequency of fluctuations in the sound field caused by internal solitary waves in real conditions. The method can be applied to the inversion of internal solitary wave phase speed which related to other parameters such as amplitude and characteristic width by theory. It is anticipated that this method can help realize the monitoring of internal solitary waves using acoustic paths.

Generation and Propagation of Flexoelectricity-Induced Solitons in Nematic Liquid Crystals.

Solitons in nematic liquid crystals facilitate the rapid transport and sensing in microfluidic systems. Little is known about the elementary conditions needed to create solitons in nematic materials. In this study, we apply a combination of theory, computational simulations, and experiments to examine the formation and propagation of solitary waves, or "solitons", in nematic liquid crystals under the influence of an alternating current (AC) electric field. We find that these solitary waves exhibit "butterfly"-like or "bullet"-like structures that travel in the direction perpendicular to the applied electric field. Such structures propagate over long distances without losing their initial shape. The theoretical framework adopted here helps identify several key factors leading to the formation of solitons in the absence of electrostatic interactions. These factors include surface irregularities, flexoelectric polarization, unequal elastic constants, and negative anisotropic dielectric permittivity. The results of simulations are shown to be in good agreement with our own experimental observations, serving to establish the validity of the theoretical concepts and ideas advanced in this work.

Propagation of compression solitary waves on tensegrity-like lattices made of truncated octahedrons

This work studies the properties of compression solitary waves propagating through one-dimensional mass–spring lattices, whose unit cells show an interaction law mimicking that of a truncated tensegrity octahedron. Analytic methods based on the Weierstrass criterion for compact solitary waves, and the long wave approximation theory are employed to demonstrate that the analyzed systems support compression solitary waves in a suitable range of wave speeds. These systems exhibit an initially soft response, which progressively turns into an elastically hardening behavior ending with a linear branch in the pre-buckling regime of the units cells. Explicit formulae are given for the lower and upper bounds of the wave speed interval that produce compact solitary waves, together with analytic laws of the shape of the traveling wave. Numerical simulations provide a validation of the presented theory.

Solitary wave solutions for the (1+1)-dimensional nonlinear Kakutani–Matsuuchi model of internal gravity waves

The Kakutani–Matsuuchi (KM) equation provides a mathematical framework for studying the dynamics of extended nonlinear internal gravity waves in a stratified fluid medium, including important phenomena such as solitary wave propagation. This study explores various analytical and semi-analytical methods to obtain accurate solutions for the (1＋1)-dimensional KM model.The primary objective of this research is to derive new solitary wave and periodic wave solutions, and subsequently validate these analytical techniques by comparing them with solutions obtained through the Adomian decomposition method. The KM model governs the dynamics of nonlinear waves and exhibits significant connections with other nonlinear equations, notably the (KdV) equation. The analytical methods, particularly the Khater II and auxiliary equation sub-equation methods, lead to closed-form solutions by reducing the partial differential equation to a system of ordinary differential equations. Conversely, the Adomian method provides a semi-analytical solution expressed as an infinite series.Solitary and periodic traveling wave solutions are systematically derived using the aforementioned analytical techniques. To verify their accuracy, solutions obtained through Adomian decomposition are computed recursively and compared. The results highlight the effectiveness of the analytical methods in discovering new exact solutions, thereby enhancing our understanding of the physical phenomena described by the KM equation. These solutions contribute to a more nuanced understanding of the properties and behaviors of internal waves, thereby enriching our overall knowledge in this field. Consequently, this research further develops analytical solution techniques tailored for nonlinear wave models prevalent in fluid dynamics.

Landau damping effects on dust ion-acoustic solitary waves in a nonthermal pair-ion plasma

The Landau damping effects on the nonlinear propagation of dust ion-acoustic solitary waves (DIASWs) are studied in an electron-free unmagnetized collisionless dusty pair-ion plasma. The two species of nonthermal ions (positive and negative) are described by the kinetic Vlasov equations, whereas the massive charged dust grains form only the background plasma. Using the multi-scale reductive perturbation technique generalized for the applications to the Vlasov equation, we derive a modified Korteweg–de Vries (KdV) equation that governs the evolution of DIASWs with the effects of linear resonance, in particular, linear Landau damping. The properties of the phase velocity and the Landau damping rate of DIASWs are studied with the effects of positive and negative-ion nonthermality parameters ( α p , α n ), the ratios of the positive to negative ion masses (m) and temperatures (T) as well as the dust to negative-ion number density ratio (δ). It is found that, depend on the degree of positive to negative ion mass ratios (m), both of damped and growing oscillations occur in a collisionless dusty pair-ion plasma due to the resonance phenomena between the wave and the nonthermal particles of the system. The properties of the decay rates of the amplitude of the KdV soliton with a small effect of Landau damping are also studied with the above system of parameters. The results may be useful for understanding the localization of solitary pulses and associated resonance damping and/or growing oscillations of the wave in laboratory and space plasmas, in which the number density of free electrons is much smaller than that of ions and highly charged heavy, micron seized dust grains.

Propagation of solitary waves in origami-inspired metamaterials

We propose a design strategy for creating origami-like mechanical metamaterials with diverse non-linear mechanical properties and capable of remote actuation. The proposed triangulated cylindrical origami (TCO)-inspired metamaterials enable the highly desirable strain-softening/hardening and snap-through behaviors via a multi-material and highly deformable hinge design. Moreover, we couple these novel non-linear mechanical properties of the TCO origami-inspired metamaterials with the transformative ability of hard-magnetic active materials, allowing for untethered shape- and property-actuation in the developed metamaterials. We develop a mathematical modeling framework for the proposed TCO origami-inspired metamaterials, building on approximating the highly deformable hinges as a combination of longitudinal and rotational springs. We validate the accuracy of the developed mathematical modeling approach by comparing the analytically predicted compressive response of a unit cell structure with the corresponding numerical and experimental results. Using the developed mathematical modeling framework, we investigate the magnetic field-induced large deformation and superimposed solitary wave propagation in the TCO origami-inspired metamaterial system. We show that the proposed metamaterial allows us to tune the key characteristics of the enabled non-linear solitary waves, including their characteristic width and amplitude. The proposed design strategy for readily manufacturable origami-inspired metamaterial systems paves a novel path for practical engineering applications. Our studies also underscore the potential of magneto-mechanical interaction in the design of reconfigurable metamaterial systems with superior non-linear mechanical and elastic wave properties.

Propagation of solitary wave in micro-crystalline materials

In this article, the propagation of waves in micro-crystalline materials is governed by the structure of the strain wave equation and takes into consideration various dimensions of micro-crystalline. Micro-crystalline materials that are deserving of special attention in material physics. The strain wave equation represents the dynamic behavior associated with multiple phenomena of a physical nature. The new extended direct algebraic methodology is applied to acquire the different types of exact solitonic solutions. This technique stands out as one of the most effective approaches for producing a diverse set of exact solutions to nonlinear partial differential equations. By applying a new extended direct algebraic approach, we get solutions in the form of smooth periodic, anti-dark, anti-bell-shape, periodic bright, Combined bright-dark soliton, mixed-periodic solution, anti-kink formations, Stumpons, mixed periodic solitons, and decaying cusped solitons. Furthermore, two-dimensional, three-dimensional, and contour plots are created for different solutions, helping us make sense of their physical significance more clearly. The importance of the obtained results lies in their ability to represent diverse and complex phenomena in mathematical and physical systems.

Excitation and stability of nonlinear waves by a pair of steady waves in incompressible boundary layers

The research explores the generation and stability of nonlinear waves in incompressible boundary layers, spotlighting the effects of dual steady waves. Using the Benjamin-Ono equation, modified for the incorporation of steady waves, we provide insights into the solitary wave generation process. A perturbed wave oscillator system is used for analyzing the stability of these nonlinear waves, uncovering that the loss of stability in low-order oscillators primarily governs wave transition and energy. Further, the study highlights the enlightening significance of complex terrain on the generation of nonlinear waves. Since the influence of terrain on the fluid passing over it usually appears as the external excitation of stationary waves, our study has important implications for terrain-fluid interactions.

Lie symmetries, solitary wave solutions, and conservation laws of coupled KdV‐mKdV equation for internal gravity waves

The propagation of nonlinear solitary and shallow water waves can be examined by nonlinear evolution equations. The dynamics of nonlinear behavior are described by exact solutions having parametric functions. The integrability of nonlinear equation discloses various characteristics of real phenomenon with continuous and fluctuating background. This work aims to generate symmetry reductions and exact solutions of KdV‐mKdV equation, which is a completely integrable system of nonlinear equations and describes combined solitary wave effects in inhomogeneous medium. The infinitesimal generators and their commutative relations are deduced under invariance property of Lie groups. The invariance property provides a symmetry reduction of governing system. Therefore, a continuous process of reductions transmutes the KdV‐mKdV equation to an equivalent system of ODEs. This system of ODEs leads to the exact solutions involving several arbitrary constants and functions. Such obtained results are generalized than earlier works and never reported in literature. Furthermore, adjoint equation and conserved quantities associated with Lagrangian formulation are constructed under Lie symmetries. To reveal the significance of governing phenomenon, the exact solutions are traced via numerical simulation and thus the graphical structures demonstrate line multisoliton, single soliton, lumps, parabolic and stationary wave profiles.

Nonlinear dust-ion acoustic solitary waves for collisional electronegative dusty plasma in the presence of trapped electron distribution

We have investigated the characteristics of nonlinear propagation of dust-ion acoustic solitary waves in collisional electronegative unmagnetized dusty plasma, which consists of trapped electrons, Boltzmann negative ions, mobile positive ions, mobile negative dust particulates, and a uniform background of neutral particles. In account of ion-neutral collisions, the modified Korteweg–de Vries relation has been derived by employing the standard reductive perturbation method. Analytical and numerical solutions of the damped Korteweg–de Vries equation has been presented in which finite difference method is used for numerical solution. On the other hand, the dust charging equation has been solved by using Newton’s Raphson method. It is found that the temperature ratio of free to trapped electrons, ion-neutral collision, concentration of negative ions, dust number density, and dust density perturbation modify the basic properties of the dust-ion acoustic solitary waves. The temporal evolution of dust-ion acoustic solitary waves is crucial as it affects the amplitude and width of wave structure. In addition, the analytical and numerical solutions are compared, and their deviation is graphically illustrated.

Generation and Evolution of Internal Solitary Waves in a Coastal Plain Estuary

Abstract Large-amplitude internal solitary waves were recently observed in a coastal plain estuary and were hypothesized to evolve from an internal lee wave generated at the channel–shoal interface. To test this mechanism, a 3D nonhydrostatic model with nested domains and adaptive grids was used to investigate the generation of the internal solitary waves and their subsequent nonlinear evolution. A complex sequence of wave propagation and transformation was documented and interpreted using the nonlinear wave theory based on the Korteweg–de Vries equation. During the ebb tide a mode-2 internal lee wave is generated by the interaction between lateral flows and channel–shoal topography. This mode-2 lee wave subsequently propagates onto the shallow shoal and transforms into a mode-1 wave of elevation as strong mixing on the flood tide erases stratification in the bottom boundary layer and the lower branch of the mode-2 wave. The mode-1 wave of elevation evolves into an internal solitary wave due to nonlinear steepening and spatial changes in the wave phase speed. As the solitary wave of elevation continues to propagate over the shoaling bottom, the leading edge moves ahead as a rarefaction wave while the trailing edge steepens and disintegrates into a train of rank-ordered internal solitary waves, due to the combined effects of shoaling and dispersion. Strong turbulence in the bottom boundary layer dissipates wave energy and causes the eventual destruction of the solitary waves. In the meantime, the internal solitary waves can generate elevated shear and dissipation rate in local regions. Significance Statement In the coastal ocean nonlinear internal solitary waves are widely recognized to play an important role in generating turbulent mixing, modulating short-term variability of nearshore ecosystem, and transporting sediment and biochemical materials. However, their effects on shallow and stratified estuaries are poorly known and have been rarely studied. The nonhydrostatic model simulations presented in this paper shed new light into the generation, propagation, and transformation of the internal solitary waves in a coastal plain estuary.

Observation of non-planar dust acoustic solitary wave in a strongly coupled dusty plasma

The nonlinear evolution and propagation of a stable dust acoustic solitary wave (DASW) in a non-planar geometry is investigated here. The experiment is performed in a strongly coupled dusty plasma consisting of monodisperse micrometer sized particles levitated in the sheath of a capacitively coupled radio frequency argon plasma. The non-planar waves are generated with the help of a cylindrical conducting exciter pin placed at the center of the homogeneous dust cloud. A negative excitation pulse is used to create a dust void and a dust density perturbation simultaneously around the exciter. From the edge of the void, the density perturbation propagates as a nonlinear (cylindrical) non-planar DASW. The characteristics of the solitary wave are measured using image analysis of the recorded video of wave propagation. The numerical solution of the modified Korteweg–de Vries equation with an additional term to take care of the non-planar geometry is compared with the experimental observation. The wave amplitude and width are measured as a function of time and compared with the theoretical predictions.

Oblique Propagation of Dissipative Ion-Acoustic Solitary Waves in a Magnetized Viscous Plasma With κ-Gurevich Distributed Electrons

Oblique Propagation of Dissipative Ion-Acoustic Solitary Waves in a Magnetized Viscous Plasma With κ-Gurevich Distributed Electrons

Solitons, dispersive shock waves and Noel Frederick Smyth

Noel Frederick Smyth (NFS), a Fellow of the Australian Mathematical Society and a Professor of Nonlinear Waves in the School of Mathematics at the University of Edinburgh, passed away on February 5, 2023. NFS was a prominent figure among applied mathematicians who worked on nonlinear wave theory in a broad range of areas. Throughout his academic career, which spanned nearly forty years, NFS developed mathematical models, ideas, and techniques that have had a large impact on the understanding of wave motion in diverse media. His major research emphasis primarily involved the propagation of solitary waves, or solitons, and dispersive shock waves, or undular bores, in various media, including optical fibers, liquid crystals, shallow waters and atmosphere. Several approaches he developed have proven effective in analyzing the dynamics and modulations of related wave phenomena. This tribute in the journal of Wave Motion aims to provide a brief biographical sketch of NFS, discuss his major research achievements, showcase his scientific competence, untiring mentorship and unwavering dedication, as well as share final thoughts from his former students, colleagues, friends, and family. The authors had a special connection with NFS on both on personal and professional levels and hold deep gratitude for him and his invaluable work. In recognition of his achievements in applied mathematics, Wave Motion hosts a Special Issue entitled “Modelling Nonlinear Wave Phenomena: From Theory to Applications,” which presents the recent advancements in this field.

Investigating exact solutions, sensitivity, and chaotic behavior of multi-fractional order stochastic Davey–Sewartson equations for hydrodynamics research applications

Our research aims to explore the fractional derivative of the Stochastic Davey–Stewartson equation (FDSDSEs) and make contributions in seven aspects: Firstly, we discovered previously unknown exact solutions for FDSDSEs, including Weierstrass elliptic function solutions. These findings provide new insights for our understanding and analysis of these equations. Secondly, we analyzed the effect of noise on stochastic solutions. We found that higher noise intensity can disrupt patterns and result in flatter surfaces. However, we observed that multiplicative noise can stabilize the solution to some extent. This reveal the role of noise in stochastic dynamics and has important implications for wave behavior in the ocean environment. Thirdly, we emphasized the impact of fractional derivatives on noise dynamics. Our research indicates the importance of considering the order of derivatives α in analysis and modeling. Different order derivatives have different effects on noise, which is significant for ocean researchers in selecting appropriate derivatives to study stochastic systems. Fourthly, we compared the effects of different fractional derivatives on noise in stochastic solutions. We found that choosing appropriate derivative orders can more accurately describe wave behavior in the ocean environment. This discovery has important implications for improving wave models and predicting ocean waves. Fifthly, we studied the influence of tilted wave variations in FDSDSE solutions. We observed spiral-like patterns, providing new insights into wave propagation in the ocean. This is significant for understanding wave behavior in the ocean and relevant ocean engineering applications. Sixthly, we explored the phase diagrams and chaotic behavior of FDSDSE through sensitivity analysis and perturbation factors. This enhances our understanding of practical applications and control strategies in ocean hydrodynamics research and is also important for delving into the dynamic behavior and phase diagrams of these equations. Finally, we compared our research results with well-known wave phenomena in the ocean through visualization, highlighting the practical relevance of our study. These comparisons involve random propagation of ocean solitary waves, twisting propagation of ocean waves, and rotating propagation of solitary waves, providing some inspiration for advancing the fields of ocean science and engineering.

Existence and uniqueness solution analysis of time-fractional unstable nonlinear Schrödinger equation

The time-fractional unstable nonlinear Schrödinger (NLS) equations capture the time evolution of disturbances within media, tailored for describing phenomena in unstable media to help model and understand the intricate dynamics of systems prone to instability, the behavior of disturbances in complex and unstable environments and many more. In this study, we investigate the exact and analytical solutions of time-fractional unstable nonlinear Schrödinger (NLS) equations with the time-fractional β-time derivative, a powerful technique known as the sine-Gordon expansion (SGE) method is used. Non-locality behaviors that cannot be modeled using classical calculus are included in this equation. It discusses the relationships between waves of different frequencies or the same frequency but with distinct polarizations having a diverse set of key applications in nonlinear optics. We begin by using a fixed-point argument to prove the existence and uniqueness of solutions to the time-fractional problem under consideration. The partial differential equation of fractional order is transformed into an ordinary differential equation using the complex transformation. Numerous exact solutions are achieved with all the arbitrary parameters. The specific values of the obtained solutions' associated parameters are analyzed graphically with 3D plots as multiple soliton types of different wave solutions with the help of symbolic software. Understanding that the features of the solutions are far from intuitive because it is based on the parameter selection from the figures is difficult. The main objective of this paper is to investigate some fresh and further general solitary wave solutions to the suggested equation that properly explain the above-stated phenomena.

On the arbitrary amplitude ion-acoustic structures in an anisotropic non-Maxwellian electron–positron–ion magnetoplasma

This paper comprehensively investigates the oblique propagation of ion-acoustic solitary waves (IASWs) with arbitrary amplitude in a magnetoplasma consisting of inertialess non-Maxwellian (nonthermal) electrons, inertialess Maxwellian positrons, and inertial adiabatically heated ions. It is postulated that the positive ions demonstrate adiabatic behavior that is distinguished by anisotropic thermal pressure. The study utilizes Sagdeev's pseudopotential theory to analyze the fluid equations of the plasma model and reduce them to the energy equation. Different plasma configuration factors, such as nonthermal parameters, positron concentration, and parallel and perpendicular ion pressure, are being studied to see how they affect the properties of solitary waves with large amplitudes. The findings demonstrate the simultaneous coexistence of compressive and rarefactive IASWs, significantly influenced by positrons and nonthermal electron parameters. The study provides valuable insights into wave phenomena in magnetized plasmas and presents possible applications in both Space and laboratory plasma environments.

Generation of internal solitary waves by the Mackenzie River plume in the coastal Arctic Ocean

High-resolution spaceborne synthetic aperture radar (SAR) images have verified the wide existence of internal solitary waves (ISWs) over the Chukchi and Beaufort Seas. A major ISW generation hotspot has been observed at the mouth of the Mackenzie River. Considering the weak tidal currents and relatively flat topography of the Mackenzie Shelf, such ISWs are unlikely to be generated by tide–topography interactions. However, this is more likely caused by the intrusion of river plumes. Therefore, the generation of ISWs by the Mackenzie River plume is investigated numerically. A series of numerical simulations are conducted to explore the influence of stratification, river plume strength, and Earth's rotation on the generation and evolution of ISWs. The results indicate that the Mackenzie River plume is an essential ISW source for the coastal Arctic Ocean. The amplitude of the ISWs is affected by the intrusion strength of the Mackenzie River plume. In addition to the direct observational evidence from summer, the numerical results show that the environmental conditions in winter are suitable for the generation of ISWs. Rotation affects the amplitude of the generated ISWs and the number of ISWs in an ISW packet by modulating the plume intrusion strength and dispersing the ISWs. This study highlights the crucial role of the river plume mechanism in exciting ISWs and emphasizes the importance of ISWs for vertical mixing in the Arctic Ocean.