# gst: dispersive shock waves in periodic lattices.

<< ️(AA) introduce and systematically investigate the generation of dispersive shock waves, which arise naturally in physical settings such as optical waveguide arrays and superfluids confined within optical lattices. The underlying physically relevant model is a nonlinear Schrödinger (NLS) equation with a periodic potential. (They) consider the evolution of piecewise smooth initial data composed of two distinct nonlinear periodic eigenmodes. >>

<< ️️The resulting tight-binding approximation is shown to display higher-fidelity for deeper periodic potentials. This reduced (discrete) DNLS model effectively models the dynamics at the minima of the periodic potential of the original continuum NLS. >>

Su Yang, Sathyanarayanan Chandramouli, P. G. Kevrekidis. Dispersive shock waves in periodic lattices. arXiv: 2511.14549v3 [nlin.PS]. Apr 9,  2026.

https://arxiv.org/abs/2511.14549

Phys. Rev. E 113, 044204. Apr 10, 2026.

https://journals.aps.org/pre/abstract/10.1103/sppv-dr5c

Also: waves, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, dispersive shock waves.

# gst: unidirectional flow from continuous broken symmetries.

<< ️Locally broken symmetries are used across fields to transport matter, particles and information in preferential directions. Beyond local mechanisms, spatially distributed nonlinearities in crystalline media have enabled non-reciprocal transport, a rectification mechanism that operates continuously across scales and frequencies. Here, (AA) show that this concept applies beyond condensed matter, to fluid transport in living organisms and artificial systems. >>

<< ️(They) take the example of the lymphatic vascular system, which transports interstitial fluid in mammals, and demonstrate that distributed leaflets act as continuous broken symmetries. (They) build an artificial model of a collecting lymphatic and investigate the naturally richer dynamics of unidirectional transport that arises from spatiotemporal excitations. (They) observe robust and scalable transport for any waveshape and external pressure gradients. (They) show experimentally and theoretically that the contraction wavelength, directionality, and pulsatility control the flow rate. In particular, (They) counterintuitively find waveshapes that maximize transport when propagating against the direction of the flow. >>

<< ️Overall, (Their) findings advance the understanding of unidirectional fluid transport in living systems and beyond, and reveal how coupling nonlinearities with spatiotemporal excitations can tune such transport across fields. >>

Aaron Winn, Justine Parmentier, Eleni Katifori, et al. Unidirectional flow from continuous broken symmetries. arXiv: 2603.27474v1 [cond-mat.soft]. Mar 29, 2026.

https://arxiv.org/abs/2603.27474

Also: waves, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, particle, non-reciprocal transport, broken symmetries, spatiotemporal excitations, lymphatic vascular system.

# gst: extreme (rogue) waves; from theory to experiments.

<< ️In this Chapter, (AA) review key theoretical and experimental advances in the study of extreme nonlinear wave events, called rogue waves (RWs), in both single-component attractively interacting and two-component repulsive mixtures of ultracold quantum gases. Starting from the exact rational solutions of the integrable focusing nonlinear Schroedinger model, the hierarchy of RW solutions is exemplified. These range from the Peregrine soliton (PS) and, related to it, the destabilization into a multi-peak cascade of PSs dubbed "Christmas-tree", to the Akhmediev breather, and Kuznetsov-Ma soliton as well as higher-order RWs. Emphasis is placed on their controllable dynamical emergence and characteristics in non-integrable quantum many-body systems described by Gross-Pitaevskii models and extensions thereof through different protocols such as modulational instability, gradient catastrophe, and dam-break flows. >>

<< ️(They) further discuss how immiscible particle-imbalanced repulsive mixtures can be cast into effective attractive single-component environments capable of hosting RWs. Next, state-of-the-art experimental techniques are summarized within the ultracold realm that can be utilized to realize solitary waves, modulational instability, dispersive shock waves and RWs including the very recent first experimental observation of the PS, enabled through engineered effective focusing interactions and precise dynamical triggering. >>

<< ️Observations of these extreme events in water waves, nonlinear optics and beyond are also outlined, highlighting their broader relevance and potential of emergence in disparate physical settings. (Their) exposition aims at showcasing ultracold atomic gases as versatile platforms for controllably generating and probing extreme nonlinear events, among others, in the quantum realm across integrable and non-integrable settings. >>

A. Chabchoub, P. Engels, P. G. Kevrekidis, et al. Extreme (Rogue) Waves: From Theory to Experiments in Ultracold Gases and Beyond. arXiv: 2603.25908v1 [cond-mat.quant-gas]. Mar 26, 2026.

https://arxiv.org/abs/2603.25908

Also: soliton, waves, particle, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, extreme events, rogue waves, solitary waves, dispersive shock waves, modulational instability, gradient catastrophe, dam-break flows, Peregrine soliton, PS Christmas-tree, Akhmediev breather, Kuznetsov-Ma soliton.

# gst: comparative analysis of detonation and shock waves interacting with droplets.

<< ️The interaction mechanisms among detonation waves, shock waves, and liquid droplets play a critical role in advancing propulsion technologies such as rotating detonation engines. This (AA) study conducts a detailed comparison of wave dynamics, cavitation phenomena, and droplet deformation during the detonation wave and the shock-wave interactions with a water droplet, employing a high-resolution numerical model that integrates multicomponent compressible fluid dynamics, chemical reactions, and phase transition effects. >>

<< ️Numerical simulations reveal distinct characteristics between detonation and shock-induced phenomena. Unlike the shock wave, detonation-induced reflected shock waves exhibit significantly higher propagation velocities while maintaining nearly identical wave configurations, a phenomenon this (AA) study mechanistically explains by the unique postwave conditions. >> 

<< ️A fundamental distinction arises in cavitation dynamics between the detonation wave and the shock wave, with the detonation-wave triggering cavitation zone collapse at significantly higher rates compared with the shock wave. This difference is attributed to the shorter persistence of low-pressure regions behind the detonation front, where rapid attenuation of postwave pressure and flow velocity occurs. >>

<< ️Moreover, detonation-induced flow interactions create unique droplet fragmentation patterns. The rapid postwave velocity reduction prevents Rayleigh-Taylor instability-driven forward jet formation, instead causing leeward-side flattening of the droplet through the vortex in the recirculation zone. >>

Hanbing Zou, Xin Jin, Haotian Chen, et al. Comparative analysis of detonation  and shock waves interacting with droplets: Characteristics and mechanisms. Phys. Rev. Fluids 11, 034303. Mar 18, 2026.

https://journals.aps.org/prfluids/abstract/10.1103/mp9z-tlk3  

Also: waves, drop, droplet, droploid, bubble, collapse, vortex, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, shock-waves, drop, droplet, droploid, bubble, collapse, vortex, transitions, phase transition, cavitation, detonation wave, detonation front, droplet fragmentation patterns. 

# gst: geometry of contraction-induced flows.

<< ️Peristalsis is the driving mechanism behind a broad array of biological and engineered flows. In peristaltic pumping, a wavelike contraction of the tube wall produces local changes in volume which induce flow. Net flow arises due to geometric nonlinearities in the momentum equation, which must be properly captured to compute the flow accurately. >>

<< ️While most previous models focus on radius-imposed peristalsis, they often neglect longitudinal length changes—a natural consequence of radial contraction in elastic materials. In this paper, to capture a more accurate picture of peristaltic pumping, (AA) calculate the flow in an elastic vessel undergoing contractions in the transverse and longitudinal directions simultaneously, keeping the geometric nonlinearities arising in the strain. >>

<< ️(They) demonstrate that transverse and longitudinal contractions induce instantaneous flows at the same order in wall strain but in opposite directions. (They) investigate the influence of the wall's Poisson ratio on the flow profile. Incompressible walls suppress flow by minimizing local volume changes, whereas auxetic walls enhance flow. For radius-imposed peristaltic waves, wall incompressibility reduces both reflux and particle trapping. In contrast, length-imposed waves typically generate backflow, although trapping can still occur at large amplitudes for some Poisson ratios. >>

Aaron Winn, Eleni Katifori. Geometry of contraction-induced flows. Phys. Rev. Fluids 11, 033101. Mar 12, 2026.

https://journals.aps.org/prfluids/abstract/10.1103/pw9s-vvf4

arXiv: 2510.24016v1 [physics.flu-dyn]. Oct 28, 2025.

https://arxiv.org/abs/2510.24016

Also: waves, elastic, network, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, elasticity, networks, peristalsis, peristaltic pumping, peristaltic waves, wavelike contractions, transverse and longitudinal contractions, longitudinal length changes, instantaneous flows, auxetic walls, backflows.

# gst: defect states as a precursor of the chimera states in a ring of non-locally coupled oscillators.

<< ️(AA) investigate the transition from synchronized to chimera states in a ring of non-locally coupled phase oscillators. (Their) focus is on the intermediate defect states, where solitary waves in the phase gradient profile travel at a constant speed. These traveling defects serve as a dynamical precursor for the nucleation of chimera clusters. The fraction of samples exhibiting defect states increases with the phase delay α and peaks at α_c, where the system crosses over to asynchronous states filled with chimera clusters. While the traveling speed, number, and width of these defects increase with α, the total spatial extent of the defects remains robust against the system size N. >> 

Tianjing Zhou, Nariya Uchida. Defect states as a precursor of the chimera states in a ring of non-locally coupled oscillators. arXiv: 2602.10533v1 [nlin.AO]. Feb 11, 2026.

https://arxiv.org/abs/2602.10533

Also: transition, chimera, waves, soliton, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, transitions, chimera, chimera clusters, coupled phase oscillators, intermediate defect states, solitary waves, asynchronous states. 

# gst: time-delayed dynamics in regular Kuramoto networks with inertia: multistability, traveling waves, chimera states, and transitions to seizure-like activity.

<< ️This (AA) study examines the complex interplay between inertia and time delay in regular rotor networks within the framework of the second-order Kuramoto model. By combining analytical and numerical methods, (AA) demonstrate that intrinsic time delays -- arising from finite information transmission speeds - induce multistability among fully synchronized phase-locked states. >>

<< ️Unlike systems without inertia, the presence of inertia destabilizes these phase-locked states, reduces their basin of attraction, and gives rise to nonlinear phase-locked dynamics over specific inertia ranges. >>

<< ️In addition, (They) show that time delays promote the emergence of turbulent chimera states, while inertia enhances their spatial extent. Notably, the combined influence of inertia and time delay produces dynamic patterns reminiscent of partial epileptic seizures. >>

Esmaeil Mahdavi, Mina Zarei, Philipp Hövel, Farhad Shahbazi. Time-Delayed Dynamics in Regular Kuramoto Networks with Inertia: Multistability, Traveling Waves, Chimera States, and Transitions to Seizure-Like Activity.  arXiv: 2512.16640v1 [nlin.AO]. Dec 18, 2025.

https://arxiv.org/abs/2512.16640

Also: network, transition, waves, chimera, turbulence, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, networks, transitions, waves, chimera, turbulence, inertia, time delay, multistability, epileptic seizures.

# gst: triadic instabilities of internal wave standing modes.

<< ️This (AA) article presents (their) experimental study of the nonlinear destabilization of an internal wave standing mode in a uniformly stratified fluid within a rectangular domain. (They) measure the linear response of the system and target its resonances to generate a high-amplitude standing mode, prone to instabilities. Using modal decomposition tools, (They) determine the characteristics of the secondary waves and show that they have a standing-mode spatial structure. Box resonance conditions associated with nonlinear resonance conditions lead to a significant deviation from the internal wave dispersion relation and complex nonlinear interaction dynamics. >>

<< Following previous work, (AA) develop a weakly nonlinear analysis to understand the secondary wave characteristics. This approach, validated by experimental results, shows that the secondary wave characteristics as well as the general nonlinear dynamics are highly sensitive to the domain geometry and to the forcing mode. >>

Julie Deleuze, Ilias Sibgatullin, Philippe Odier, Sylvain Joubaud. Triadic instabilities of internal wave standing modes. Phys. Rev. Fluids 10, 124803. Dec 8, 2025.

https://journals.aps.org/prfluids/abstract/10.1103/2pvv-wkc4

Also: waves, instability, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, instability.

# gst: bursting bubbles in Herschel-Bulkley fluids, dynamics and jetting transitions.

<< ️When a bubble rises to a free surface, its bursting dynamics in Newtonian fluids are governed by the interplay between viscous, capillary, and gravitational forces. In this work, (AA) extend this classical problem to Herschel-Bulkley fluids, elucidating the role of viscoplasticity and non-Newtonian rheology in bubble bursting. Using direct numerical simulations validated against experiments, (They) systematically explore the influence of the key governing dimensionless parameters, such as the Bond number, the Ohnesorge number, the shear-dependent behavior and the plastocapillary number, each varied over several orders of magnitude. >>

<< ️(AA) results reveal that viscoplasticity strongly controls the evolution and interaction of capillary waves within the cavity formed upon bubble rupture. Shear-thinning and shear-thickening effects are significant only for moderate Ohnesorge numbers, while at large Ohnesorge values the free surface dynamics converge to a non-flat equilibrium shape once the internal stresses fall below the yield stress. >>

<< ️These (AA) findings provide new insights into the coupled effects of viscosity, gravity, yield stress, and shear-dependent rheology in multiphase flows, with broad implications for natural and industrial processes involving gas-liquid interfaces. >>

A. H. Ghaemi, Z. Yang, A. Huang, et al. Bursting bubbles in Herschel-Bulkley fluids: dynamics and jetting transitions. arXiv: 2511.23345v1 [physics.flu-dyn]. Nov 28, 2025.

https://arxiv.org/abs/2511.23345

Also: bubble, waves, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, bubble, waves, capillary waves, bubble bursting, bubble rupture, viscosity, capillary and gravitational forces, shear-thinning and shear-thickening effects, yield stress, free surface dynamics, non-flat equilibrium.

# gst: instability triggered by mixed convection in a thin fluid layer.

<< ️(AA) investigate the convective stability of a thin, infinite fluid layer with a rectangular cross-section, subject to imposed heat fluxes at the top and bottom and fixed temperature along the vertical sides. The instability threshold depends on the Prandtl number as well as the normalized flux difference (f) and decreases with the aspect ratio (ϵ), following a ϵf^−1 power law. >>

<< ️Using 3D initial value and 2D eigenvalue calculations, (They) identify a dominant 3D mode characterized by two transverse standing waves attached to the domain edges. (They) characterize the dominant mode’s frequency and transverse wave number as functions of the Rayleigh number and aspect ratio. An analytical asymptotic solution for the base state in the bulk is obtained, valid over most of the domain and increasingly accurate for lower aspect ratios. >>

<< A local stability analysis, based on the analytical base state, reveals oscillatory transverse instabilities consistent with the global instability characteristics. The source term for this most unstable mode appears to be interactions between vertical shear and horizontal temperature gradients. >>

Florian Rein, Keaton J. Burns, Stefan G. Llewellyn Smith, et al. Instability triggered by mixed convection in a thin fluid layer. arXiv: 2512.02331v1 [physics.flu-dyn]. Dec 2, 2025.

https://arxiv.org/abs/2512.02331

Also: waves, instability, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, instability, transitions, convection, vertical shear, horizontal temperature gradients.

# gst: two instabilities in one liquid sheet.

<< ️Two cylindrical liquid jets (dia = 1 mm) of a glycerol-water mixture (80/20) impinge at 90º to one another, creating a thin liquid sheet bordered by a thick rim. Classical fish-bone shapes (sheet-thread-droplet) are formed where the rim instability is driven by Rayleigh-Plateau type mechanisms. >>

<< ️Here (AA) also see fish-bone shapes occurring for similar reasons. However, the waves on the sheet are formed by small imbalances between the two jet velocities (natural pipe driven oscillation), rather than the traditional Kelvin-Helmholtz instability. (They) stroboscopic photograph of the sheet reveals that both of these instabilities can coexist within a narrow range of operating conditions. >>

<< ️The breakup of the liquid sheet (lower down) is caused by the combined instability of spatially growing waves. The liquid sheet breaks down mainly through the growth of bounded waves. These waves eventually break, forming long threads at the bottom of the sheet, which further disintegrate into droplets due to the Rayleigh-Plateau instability of threads. >>

Sandip Dighe, Hrishikesh Gadgil, Tadd Truscott. Two instabilities in one liquid sheet. Phys. Rev. Fluids 10, 110501. Nov 20, 2025

https://journals.aps.org/prfluids/abstract/10.1103/nvkn-hk4g

77th Annual Meeting of the APS Division of Fluid Dynamics (Nov 24 — 26, 2024). P2692828: Two instabilities in one liquid. 

https://gfm.aps.org/meetings/dfd-2024/673f8914d88f37002bbe76d8

Also: waves, instability, transitions, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, instability, transitions.

# gst: degrees of universality in wave turbulence

<< ️Turbulence of weakly interacting waves displays a great deal of universality: independence of the details of the interaction and of the pumping and dissipation scales. Here (AA) study how inverse turbulent cascades (from small to large scales) transition from weak to strong. (They) find that while one-loop corrections can be dependent on excitation and dissipation scales, new types of universality appear in strong turbulence. (They) contrast turbulence of spin waves in ferromagnets with turbulent cascades in the Nonlinear Schrödinger Equation (NSE) and in an MMT-like (Majda-McLaughlin-Tabak) model in higher dimensions having a multiplicative interaction vertex: vertex renormalization gives rise to dependence on the pumping (UV scale) in the former but not in the latter. >>

<< ️As a result of this spectral nonlocality, spin-wave turbulence stops being weak if one is sufficiently far from the pumping scale, even when the interaction of waves with comparable wavenumbers is weak. (AA) paraphrase this as: nonlocality enhances nonlinearity. >>

<< ️(AA) then describe strong turbulence in a multi-component version of these models with a large number of components. (They) argue that strong spin-wave turbulence is similar to turbulence of the focusing NSE, as it realizes a critical-balance state. However, UV nonlocality causes the level of spin-wave turbulence at large scales to decrease with increasing pumping level, culminating in a state that is independent of the level of pumping. >>

Jiasheng Liu, Vladimir Rosenhaus, Gregory Falkovich. Degrees of universality in wave turbulence. arXiv: 2512.04866v1 [cond-mat.stat-mech]. Dec 4, 2025.

https://arxiv.org/abs/2512.04866

Also: waves, turbulence, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, turbulence, transitions.

# gst: spontaneous emergence of solitary waves in active flow networks.

<< ️Flow networks are fundamental for understanding systems such as animal and plant vasculature or power distribution grids. These networks can encode, transmit, and transform information embodied in the spatial and temporal distribution of their flows. >>

<< ️In this work, (AA) focus on a minimal yet physically grounded system that allows (Them) to isolate the fundamental mechanisms by which active flow networks generate and regulate emergent dynamics capable of supporting information transmission. The system is composed of active units that pump fluid and elastic units that store volume. From first principles, (They) derive a discrete model-an active flow network-that enables the simulation of large systems with many interacting units. >>

<< ️Numerically, (AA) show that the pressure field can develop solitary waves, resulting in the spontaneous creation and transmission of localized packets of information stored in the physical properties of the flow. (They) characterize how these solitary waves emerge from disordered initial conditions in a one-dimensional network, and how their size and propagation speed depend on key system parameters. >>

<< ️Finally, when the elastic units are coupled to their neighbors, the solitary waves exhibit even richer dynamics, with diverse shapes and finite lifetimes that display power-law behaviors that (They) can predict analytically. >>

Rodrigo Fernández-Quevedo García, Gonçalo Cruz Antunes, Jens Harting, et al. Spontaneous emergence of solitary waves in active flow networks. arXiv: 2511.13448v1 [physics.flu-dyn]. Nov 17, 2025.

https://arxiv.org/abs/2511.13448

Also: soliton, waves, network, elastic, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, solitons, waves, solitary waves, networks, active flow networks, active matter, fluid-structure interactions, elasticity.

# gst: energy transport and chaos in a one-dimensional disordered nonlinear stub lattice

<< ️(AA) investigate energy propagation in a one-dimensional stub lattice in the presence of both disorder and nonlinearity. In the periodic case, the stub lattice hosts two dispersive bands separated by a flat band; however, (They) show that sufficiently strong disorder fills all intermediate band gaps. By mapping the two-dimensional parameter space of disorder and nonlinearity, (AA) identify three distinct dynamical regimes (weak chaos, strong chaos, and self-trapping) through numerical simulations of initially localized wave packets. >>

<< ️When disorder is strong enough to close the frequency gaps, the results closely resemble those obtained in the one-dimensional disordered discrete nonlinear Schrödinger equation and Klein-Gordon lattice model. In particular, subdiffusive spreading is observed in both the weak and strong chaos regimes, with the second moment m_2 of the norm distribution scaling as m_2 ∝ t^0.33 and m_2 ∝ t^0.5, respectively. The system’s chaotic behavior follows a similar trend, with the finite-time maximum Lyapunov exponent Λ decaying as Λ ∝ t^−0.25 and Λ ∝ t^−0.3. For moderate disorder strengths, i.e., near the point of gap closing, (They) find that the presence of small frequency gaps does not exert any noticeable influence on the spreading behavior. >>

<< ️(AA) findings extend the characterization of nonlinear disordered lattices in both weak and strong chaos regimes to other network geometries, such as the stub lattice, which serves as a representative flat-band system. >>

Su Ho Cheong, Arnold Ngapasare, et al. Energy transport and chaos in a one-dimensional disordered nonlinear stub lattice. arXiv: 2511.04159v1 [nlin.CD].  Nov 6, 2025.

https://arxiv.org/abs/2511.04159

Also: network, waves, disorder, chaos, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, networks, waves, disorder, chaos, stub lattice, subdiffusive spreading.

# gst: coupling an elastic string to an active bath: the emergence of inverse damping.

<< ️The interaction between continuous media and particles is a central topic in much of modern physics, and this (AA) paper specifically addresses the transfer of persistence and activity between particles and waves. Indeed, setting up a nonequilibrium dynamics of continuous (field) degrees of freedom requires understanding how that arises from coupling with active matter degrees of freedom. >>

<< ️Within that program, (AA) have studied a system of fast-moving, overdamped, run-and-tumble particles moving on and interacting with a slower string modeled as a scalar Klein-Gordon field. Using time scale separation and weak coupling, (They) have derived an effective fluctuation dynamics for the field after integrating out the active bath. Akin to Landau (inverse) damping, the particles induce friction on the scalar field given by an explicit time correlation for bath observables. >>

<< ️Depending on the level of activity and persistence of the active particles (and their velocity distribution), this friction can be negative, leading to instability. This emergence of negative (linear) friction for an elastic string extends previous results where the probe is a slow inertial particle in an active medium, (..), except that the acceleration (creating transverse waves) is orthogonal to the active motion. >>

Aaron Beyen, Christian Maes, Ji-Hui Pei. Coupling an elastic string to an active bath: The emergence of inverse damping. arXiv: 2505.18665v2 [cond-mat.stat-mech]. Sep 1, 2025.

https://arxiv.org/abs/2505.18665

Phys. Rev. E 112, L042103. Oct 17, 2025.

https://journals.aps.org/pre/abstract/10.1103/g1zm-23sq

Also: particle, waves, elastic, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, particles, run-and-tumble particles, waves, elasticity, elastic strings, wave-particle interactions.

# gst: apropos of waves that escape trapping; on internal wave whispering gallery modes in channels and critical-slope wave attractors.

<< ️Internal waves are an important feature of stratified fluids, both in oceanic and lake basins and in other settings. Many works have been published on the generic feature of internal wave trapping onto planar wave attractors and super-attractors in 2D & 3D and the exceptional class of standing global internal wave modes. >>

<< ️However, most of these works did not deal with waves that escape trapping. By using continuous symmetries (AA) analytically prove the existence of internal wave Whispering Gallery Modes (WGMs), internal waves that propagate continuously without getting trapped by attractors. WGMs neutral stability with respect to different perturbations enable whispering gallery beams, a continuum of rays propagating together coherently. The systems' continuous symmetries also enable projection onto 2D planes that yield effective 2D billiards preserving the original dynamics. >>

<< ️By examining rays deviating from these WGMs in parabolic channels (They) discover a new type of wave attractor which is located along the channel instead of across it as in previous works. This new wave attractor leads to a re-understanding of WGMs as sitting at the border between the two basins of attraction. >>

<< ️Finally, both critical-slope wave attractors and whispering gallery beams are used to propose explanations for along-channel energy fluxes in submarine canyons and tidal energy intensification near critical slopes. >>

Nimrod Bratspiess, Eyal Heifetz, Leo R. M. Maas. On internal wave whispering gallery modes in channels and critical-slope wave attractors. arXiv: 2510.07218v1 [physics.flu-dyn]. Oct 8, 2025.

https://arxiv.org/abs/2510.07218

Also: waves, billiard, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, internal waves, internal wave whispering gallery modes (WGMs), wave attractors, basins of attraction, billiards.

# gst: spiral defect chaos with intermittency increases mean termination time

<< ️Cardiac models are examples of excitable systems and can support stable spiral waves. For certain parameter values, however, these spiral waves can become unstable, resulting in spiral defect chaos (SDC), characterized by the continuous creation and annihilation of spiral waves and thought to underlie atrial fibrillation. During SDC, the number of spiral waves fluctuates and drops to zero at termination. >>

<< ️In this work, (AA) demonstrate that varying a single parameter allows the system to transition from SDC to a single spiral wave, passing through an intermediate regime of intermittency. In such intermittent dynamics, intervals of SDC are sandwiched between non-SDC intervals during which the number of spiral waves remains small and constant. (They) quantify this intermittency and show that the mean termination time increases significantly as the control parameter approaches values for which a single spiral wave is stable. >>

<<  In addition, (AA) observe that quasistable spiral waves may intermittently persist in part of the computational domain, while the rest of the domain exhibits SDC. >> 

Mahesh Kumar Mulimani, Wouter-Jan Rappel. Spiral defect chaos with intermittency increases mean termination time. Phys. Rev. E 112, 034203. Sep 3, 2025.

https://journals.aps.org/pre/abstract/10.1103/bwpl-qqyl

arXiv: 2505.06427v1 [nlin.CD]. May 9,  2025

https://arxiv.org/abs/2505.06427

Also: waves, intermittency, vortex, chaos, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, spiral & scroll waves, intermittency, vortex, chaos, spiral defect chaos.

# gst: shock waves in classical dust collapse.

<< ️During gravitational collapse of dust in spherical symmetry, matter particles may collide forming shell crossing singularities (SCSs) at which the Einstein equations become indeterminate. >>

<< ️(AA) show that in the case of marginally bound dust collapse, there is a unique evolution beyond SCSs such that a propagating shock wave forms, the metric remains continuous, and the stress-energy tensor dynamically becomes that of a thin shell. (They) give numerical simulations that exhibit this result. >>

Viqar Husain, Hassan Mehmood. Shock waves in classical dust collapse. Phys. Rev. Research 7, 033215. Sep 3, 2025.

https://journals.aps.org/prresearch/abstract/10.1103/b317-86qs

arXiv: 2504.14883v1 [gr-qc]. Apr 21, 2025.

https://arxiv.org/abs/2504.14883

Also: particle, singularity, collapse, waves, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, particles, singularity, shell crossing singularities, waves, shock waves, gravitational waves, collapse, dust collapse, gravitational collapse. 

# gst: falling viscoelastic liquid films on a slippery substrate.

<< This (AA) study develops a weighted-residual model for Oldroyd-B films on slippery substrates at moderate Reynolds number and large slippery length. >>

<< Linear stability analysis reveals that wall slip promotes perturbation growth rates, increases cut-off wave numbers, and accelerates long-wave propagation speed, demonstrating a destabilizing effect. Two distinct families of traveling waves are sought, which demonstrate that varying the slippery length can alter the bifurcation type of traveling wave families. >>

<< Particularly, large slippery length can cause the transition of drag-gravity regime into the drag-inertia regime. In the drag-gravity regime, slippery effect promotes the wave speed and height. However, in the drag-inertia regime, slippery effect can suppress the wave height even though the wave propagates faster. >>

<< Interestingly, plateau-type waves (They)  found in the Oldroyd-B film flow at large slippery length, which has not been reported previously. >>

Zhiwei Song, Zijing Ding. Falling viscoelastic liquid films on a slippery substrate. Phys. Rev. E 112, 025106. Aug 25, 2025. 

https://journals.aps.org/pre/abstract/10.1103/vv3p-cvk2

Also: slipping, waves, instability, transition,   in https://www.inkgmr.net/kwrds.html 

Keywords: gst, slipping, slippery substrates, waves, instability, instability of free-surface flows, transitions.

# gst: hidden qu-classical correspondence in chaotic billiards revealed by mutual information.

<< ️Avoided level crossings, commonly associated with quantum chaos, are typically interpreted as signatures of eigenstate hybridization and spatial delocalization, often viewed as ergodic spreading. >>

<< ️(AA) show that, contrary to this expectation, increasing chaos in quantum billiards enhances mutual information between conjugate phase space variables, revealing nontrivial correlations. Using an information-theoretic decomposition of eigenstate entropy, (They) demonstrate that spatial delocalization may coincide with increased mutual information between position and momentum. >>

<< These correlations track classical invariant structures in phase space and persist beyond the semiclassical regime, suggesting a robust information-theoretic manifestation of quantum-classical correspondence. >>

Kyu-Won Park, Soojoon Lee, Kabgyun Jeong. Hidden quantum-classical correspondence in chaotic billiards revealed by mutual information. Phys. Rev. E 112, 024209. Aug 13, 2025.

https://journals.aps.org/pre/abstract/10.1103/qpxx-csdj

arXiv:2505.08205v1 [nlin.CD]. May 13, 2025.

https://arxiv.org/abs/2505.08205

Also: billiard, chaos, waves, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, billiard, chaos, qu-chaos, waves, quantum-to-classical transition