# 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: apropos of shape transitions, midveins regulate the shape formation of drying leaves.

<< ️Dried leaves in nature often exhibit curled and crumpled morphologies, typically attributed to internal strain gradients that produce dome-like shapes. However, the origin of these strain gradients remains poorly understood. Although leaf veins--particularly the midvein--have been suggested to influence shape formation, their mechanical role has not been systematically investigated. >>

<< ️Here, (AA) demonstrate that mechanical constraints imposed by the midvein play a crucial role in generating the diverse morphologies that emerge during leaf drying. Combining numerical simulations and theoretical analysis, (They) show that a uniformly shrinking leaf lamina constrained by a non-shrinking midvein gives rise to two distinct types of configurations: curling-dominated and folding-dominated morphologies. In the curling-dominated regime, both S-curled and C-curled shapes emerge, with C-curled configurations more commonly observed due to their lower elastic energy. In contrast, the folding-dominated regime features folding accompanied by edge waviness. Theoretical modeling reveals a linear relationship between midvein curvature and mismatch strain, consistent with simulation results. >>

<< ️Moreover, (AA) find that the morphological outcome is governed by the ratio of bending stiffnesses between the lamina and the midvein. (They) construct a comprehensive phase diagram for the transitions between different configurations. These findings provide a mechanical framework for understanding shape formation in drying leaves, offering new insights into natural morphing processes and informing the design of bio-inspired morphable structures. >>

Kexin Guo, Yafei Zhang, et al. Midveins regulate the shape formation of drying leaves. arXiv: 2507.01813v1 [cond-mat.soft]. Jul 2, 2025.

https://arxiv.org/abs/2507.01813

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

Keywords: gst, waves, transition, leaf drying, curled and crumpled morphologies, internal strain gradients, dome-like shapes, curling-dominated and folding-dominated morphologies, edge waviness, midvein curvature and mismatch strain, life.

# 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: effective-medium theory for elastic systems with correlated disorder.

<< ️Correlated structures are intimately connected to intriguing phenomena exhibited by a variety of disordered systems such as soft colloidal gels, bio-polymer networks and colloidal suspensions near a shear jamming transition. The universal critical behavior of these systems near the onset of rigidity is often described by traditional approaches as the coherent potential approximation - a versatile version of effective-medium theory that nevertheless have hitherto lacked key ingredients to describe disorder spatial correlations. >>

<< ️Here (AA) propose a multi-purpose generalization of the coherent potential approximation to describe the mechanical behavior of elastic networks with spatially-correlated disorder. (They) apply (their) theory to a simple rigidity-percolation model for colloidal gels and study the effects of correlations in both the critical point and the overall scaling behavior. (AA) find that although the presence of spatial correlations (mimicking attractive interactions of gels) shifts the critical packing fraction to lower values, suggesting sub-isostatic behavior, the critical coordination number of the associated network remains isostatic. More importantly, (AA) discuss how their theory can be employed to describe a large variety of systems with spatially-correlated disorder. >>

Jorge M. Escobar-Agudelo, Rui Aquino, Danilo B. Liarte. Effective-medium theory for elastic systems with correlated disorder. arXiv: 2510.02090v1 [cond-mat.stat-mech]. Oct 2, 2025.

https://arxiv.org/abs/2510.02090

Also: elastic, network, disorder, disorder & fluctuations, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, elasticity, networks, elastic networks, disorder, disorder & fluctuations.

# gst: instability and self-propulsion of flexible autophoretic filaments; it was observed distinct swimming modes, steadily translating "U" and metastable rotating "S" shapes.

<< ️Over the past decade, autophoretic colloids have emerged as a prototypical system for studying self-propelled motion at microscopic scales, with promising applications in microfluidics, micro-machinery, and therapeutics. Their motion in a viscous fluid hinges on their ability to induce surface slip flows that are spatially asymmetric, from self-generated solute gradients. >>

<<️ Here, (AA) demonstrate theoretically that a straight elastic filament with homogeneous surface chemical properties -- which is otherwise immotile -- can spontaneously achieve self-propulsion by experiencing a buckling instability that serves as the symmetry-breaking mechanism. Using efficient numerical simulations, (They) characterize the nonlinear dynamics of the elastic filament and show that, over time, it attains distinct swimming modes such as a steadily translating "U" shape and a metastable rotating "S" shape when semi-flexible, and an oscillatory state when highly flexible. >>

Ursy Makanga, Akhil Varma, Panayiota Katsamba. Instability and self-propulsion of flexible autophoretic filaments. arXiv: 2509.10153v1 [cond-mat.soft]. Sep 12, 2025.

https://arxiv.org/abs/2509.10153

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

Keywords: gst, colloids, autophoretic colloids, elasticity, instability, buckling instability, symmetry-breaking mechanisms, self-propulsion, transitions.

# gst: dual role for heterogeneity in dynamic fracture.

<< ️(AA) approach the problem of heterogeneous dynamic fracture by considering spatiotemporal perturbations to planar crack fronts. Front propagation is governed by local energy balance between the elastic energy per unit area available to fracture 𝐺 and the dissipation in creating new surfaces. 𝐺 is known analytically as a perturbation series in the crack front fluctuation. >>

<< ️For dissipation that monotonically increases with the crack speed, (AA) derive an equation of motion for crack fronts that is second-order accurate. In the linear order, heterogeneity does not change the net speed of fracture. In the second order, nonlinear interactions of the front and the heterogeneous landscape populate an intermediate-scale fluctuation spectrum. >>

<< ️(AA) find that, when dissipation weakly grows with velocity, nonlinearities globally amplify dissipation and reduce the crack speed. Strong velocity dependence, however, mitigates toughening effects and may facilitate fracture. >>

Itamar Kolvin, Mokhtar Adda-Bedia, Dual Role for Heterogeneity in Dynamic Fracture. Phys. Rev. Lett. 135, 106201. Sep 3, 2025.

https://journals.aps.org/prl/abstract/10.1103/j4vb-y1ng 

arXiv: 2407.02347v1 [cond-mat.mtrl-sci]. Jul 2,  2024.

https://arxiv.org/abs/2407.02347 

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

Keywords: gst, fracture, crack, front propagation

# gst: apropos of instabilities, stability of co-annular active and passive confined fluids.

<< ️The translation and shape deformations of a passive viscous Newtonian droplet immersed in an active nematic liquid crystal under circular confinement are analyzed using a linear stability analysis. (AA) focus on the case of a sharply aligned active nematic in the limit of strong elastic relaxation in two dimensions. >>

<< ️Using an active liquid crystal model, (They) employ the Lorentz reciprocal theorem for Stokes flow to study the growth of interfacial perturbations as a result of both active and elastic stresses. >>

<< ️Instabilities are uncovered in both extensile and contractile systems, for which growth rates are calculated and presented in terms of the dimensionless ratios of active, elastic, and capillary stresses, as well as the viscosity ratio between the two fluids. >>

<< ️(AA) also extend (Their) theory to analyze the inverse scenario, namely, the stability of an active nematic droplet surrounded by a passive viscous layer. (Their) results highlight the subtle interplay of capillary, active, elastic, and viscous stresses in governing droplet stability. >>

<< ️The instabilities uncovered here may be relevant to a plethora of biological active systems, from the dynamics of passive droplets in bacterial suspensions to the organization of subcellular compartments inside the cell and the cell nucleus. >>

Tanumoy Dhar, Michael J. Shelley, David Saintillan. Stability of co-annular active and passive confined fluids. Phys. Rev. Fluids 10, 083103. Aug 21, 2025.

https://journals.aps.org/prfluids/abstract/10.1103/m5ck-v2q3

arXiv: 2501.04918v2 [cond-mat.soft]. Jul 25, 2025. 

https://arxiv.org/abs/2501.04918

Also: drop, droplet, droploid, elastic, instability, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, drop, droplet, droploid, elasticity, instability, elastic relaxation, interfacial perturbations, capillary, active, elastic, and viscous stresses.

# gst: wave-kinetic dynamics of forced-dissipated turbulent internal gravity waves

<< Internal gravity waves are an essential feature of stratified media, such as oceans and atmospheres. >>

<< To investigate their dynamics, (AA) perform simulations of the forced-dissipated kinetic equation describing the evolution of the energy spectrum of weakly nonlinear internal gravity waves. >>

<< During the early evolution, three well-known nonlocal interactions, the elastic scattering, the induced diffusion, and the parametric subharmonic instability, together with a superharmonic resonance play a prominent role. >>

<< In contrast, local interactions are responsible for anisotropic energy cascade on longer timescales. >>

AA << reveal emergence of a condensate at small horizontal wave vectors that can be interpreted as a pure wave-wave interaction-mediated layering process. >>

Vincent Labarre, Giorgio Krstulovic, Sergey Nazarenko. Wave-Kinetic Dynamics of Forced-Dissipated Turbulent Internal Gravity Waves. Phys. Rev. Lett. 135, 014101. Jul 1, 2025.

https://journals.aps.org/prl/abstract/10.1103/b82h-z21n

arXiv:2407.11469v3 [physics.flu-dyn]. Mar 28, 2025.

https://arxiv.org/abs/2407.11469

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

Keywords: gst, waves, weakness, turbulence, transitions, stratified turbulence, wave-turbulence interactions, weak turbulence.

# gst: allosteric lever: toward a principle of specific allosteric response.

<< ️Allostery, the phenomenon by which the perturbation of a molecule at one site alters its behavior at a remote functional site, enables control over biomolecular function. >>

<< ️However, a general principle of allostery, i.e., a set of quantitative and transferable “ground rules,” remains elusive. It is neither a set of structural motifs nor intrinsic motions. >>

<< ️Focusing on elastic network models, (AA) here show that an allosteric lever—a mode-coupling pattern induced by the perturbation—governs the directional, source-to-target, allosteric communication: A structural perturbation of an allosteric site couples the excitation of localized hard elastic modes with concerted long-range soft-mode relaxation. >>

<< ️Perturbations of nonallosteric sites instead couple hard and soft modes uniformly. The allosteric response is shown to be generally nonlinear and nonreciprocal, and allows for minimal structural distortions to be efficiently transmitted to specific changes at distant sites. Allosteric levers exist in proteins and “pseudoproteins”—networks designed to display an allosteric response. >>

<< ️Interestingly, protein sequences that constitute allosteric transmission channels are shown to be evolutionarily conserved. >>

Maximilian Vossel, Bert L. de Groot, Aljaž Godec. Allosteric Lever: Toward a Principle of Specific Allosteric Response. Phys. Rev. X 15, 021097. Jun 20, 2025

https://journals.aps.org/prx/abstract/10.1103/wv2k-676p

Also: allostery in FonT https://flashontrack.blogspot.com/search?q=allostery

Also: allosterico in Notes (quasi-stochastic poetry) https://inkpi.blogspot.com/search?q=allosterico

Keywords: gst, allostery, allosteric lever, elasticity, networks, elastic networks.

# gst: active drive towards elastic spinodals

<< Active matter, exemplified by adaptive living materials such as the actomyosin cytoskeleton, can navigate material parameter space, leading to unconventional mechanical responses. In particular, it can self-drive toward elastic spinodal regimes, where inhomogeneous floppy modes induce elastic degeneracy and enable a controlled interplay between rigidity loss and recovery. Proximity to such marginal states leads to stress localization and the formation of force chains that can be actively assembled and disassembled. >> 

Here AA << extend the classical notion of spinodal states to active solids and demonstrate how these extreme mechanical regimes can be actively accessed. Moreover, (They) show that in a nonlinear setting, crossing elastic spinodals generates new energy wells and makes force channeling an intrinsic feature of the emerging microstructure. >>

Ayan Roychowdhury, Madan Rao, Lev Truskinovsky. Active drive towards elastic spinodals. Phys. Rev. E 111, 065416. Jun 20, 2025.

https://journals.aps.org/pre/abstract/10.1103/h2yp-d2s2

arXiv: 2403.17517v3 [cond-mat.soft]. May 20, 2025.

https://arxiv.org/abs/2403.17517

Also: elastic, transition, instability, disorder & fluctuations, self-assembly, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, transitions, instability, disorder & fluctuations, active matter, elasticity, elastic forces, elastic deformation, elastic spinodals, self-assembly.

# gst: spreading and retraction dynamics of drop impact onto elastic surfaces.

In this study, AA << numerically investigate the impact of droplets on elastic plates using a two-phase lattice Boltzmann method, with a particular focus on how vertical surface movements influence the spreading and retraction dynamics of the droplet. >>

<< The results show that, during the spreading phase, the spreading diameter is smaller on elastic surfaces compared to rigid ones due to the vertical velocity of the surface. A universal linear evolution of the drop spreading is derived for the early stage across both rigid and elastic substrates, accounting for the surface motion by rescaling time, and this relationship is in good agreement with the numerical results. >>

<< In the retraction phase, unlike the nearly constant retraction speed observed on rigid surfaces, the retraction speed 𝑉ret oscillates with the vibrations of the elastic surface, with the oscillation period remaining relatively consistent. Further analysis reveals that the variation in 𝑉ret is not influenced by the surface's velocity but rather by its acceleration, as additional inertia is introduced during surface acceleration. >>

<< Based on this understanding, a predictive model for 𝑉ret during droplet impacts on moving surfaces is proposed, which demonstrates strong agreement with the numerical findings. >>

Yufei Ma, Haibo Huang. Spreading and retraction dynamics of drop impact onto elastic surfaces. Phys. Rev. Fluids 10, 053607. May 15, 2025.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.10.053607

Also: drop, droplet, droploid, elastic, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, drops, droplets, droploids, elasticity, elastic surfaces, surface acceleration, vertical surface movements, spreading phase, retraction phase.

# gst: defect-free and defective adaptations of crystalline sheets to stretching deformation.

<< The elastic response of the crystalline sheet to the stretching deformation in the form of wrinkles has been extensively investigated. In this work, (AA) extend this fundamental scientific question to the plastic regime by exploring the adaptations of crystalline sheets to the large uniaxial mechanical stretching. >>

AA << reveal the intermittent plastic shear deformations leading to the complete fracture of the sheets wrapping the cylinder. Specifically, systematic investigations of crystalline sheets of varying geometry show that the fracture processes can be classified into defect-free and defective categories depending on the emergence of topological defects. >>

AA << highlight the characteristic mechanical and geometric patterns in response to the large stretching deformation, including the shear-driven intermittent lattice tilting, the vortex structure in the displacement field, and the emergence of mobile and anchored dislocations as plastic excitations. >>

<< The effects of noise and initial lattice orientation on the plastic deformation of the stretched crystalline sheet are also discussed. These results advance our understanding of the atomic level on the irreversible plastic instabilities of two-dimensional crystals under large uniaxial stretching and may have potential practical implications in the precise engineering of structural instabilities in packings of covalently bonded particulate systems. >>

Ranzhi Sun, Zhenwei Yao. Defect-free and defective adaptations of crystalline sheets to stretching deformation. Phys. Rev. E 111, 055504. May 21, 2025.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.111.055504

Also: elastic, intermittency, noise, instability, vortex, defect, fracture, crack, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, elastic, noise, intermittency, instability, vortex, defect, fracture, crack, stretch, deformation, wrinkles, tilting, plastic instabilities,  plastic excitations.

# gst: elasticity of fibers prefers the chaos of turbulence.

<< The dynamics of fibers, modeled as a sequence of inertial beads linked via elastic springs, in turbulent flows is dictated by a nontrivial interplay of inertia and elasticity. Such elastic, inertial fibers preferentially sample a three-dimensional turbulent flow in a manner that is qualitatively similar to that in two dimensions [R. Singh et al., Phys. Rev. E 101, 053105 (2020)]. >>

<< Both these intrinsic features have competing effects on fiber dynamics: Inertia drives fibers away from vortices while elasticity tends to trap them inside. However, these effects swap roles at very large values. A large inertia makes the fibers sample the flow more uniformly while a very large elasticity facilitates the sampling of straining regions. >>

<< This complex sampling behavior is further corroborated by quantifying the chaotic nature of sampled flow regions. This is achieved by evaluating the maximal Lagrangian Lyapunov Exponents associated with the flow along fiber trajectories. >>

Rahul K. Singh. Elasticity of fibers prefers the chaos of turbulence. Phys. Rev. E 111, L053101. May 5, 2025.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.111.L053101

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

Keywords: gst, elasticity, turbulence, chaos, transitions

# gst: emergent oscillations and chaos in noncompliant microfluidic networks.

<< Incompressible fluids in microfluidic networks with nonrigid channels can exhibit flow rate oscillations analogous to electric current oscillations in RLC (resistor, inductor, capacitor) circuits. This is due to the elastic deformation of channel walls that can store and release fluid, as electric capacitors can store and release electric charges. This property is quantified through the compliance of the system, defined as the volume change relative to the pressure change. >>

<< In systems with rigid walls and incompressible fluid, compliance vanishes, and no oscillations can occur through this mechanism. >>

Here, AA << show that not only oscillations but also chaos can emerge in the flow-rate dynamics of noncompliant microfluidic networks with incompressible fluid. Notably, these dynamics emerge spontaneously, even under time-independent driving pressures. The underlying mechanism is governed by the effect of fluid inertia, which becomes relevant at moderate Reynolds numbers observed in microfluidic systems exhibiting complex flow patterns. >>

<< The results are established using a combination of direct numerical simulations and a reduced model derived from modal analysis. This approach enables (AA) to determine the onset of oscillations, the associated bifurcations, the oscillation frequencies and amplitudes, and their dependence on the driving pressures. >>

Yanxuan Shao, Jean-Regis Angilella, Adilson E. Motter. Emergent oscillations and chaos in noncompliant microfluidic networks. Phys. Rev. Fluids 10, 054401. May 1, 2025.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.10.054401

arXiv: 2505.00068v1 [physics.flu-dyn]. 

https://arxiv.org/abs/2505.00068

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

Keywords: gst, networks, microfluidic networks, noncompliant networks with incompressible fluid, fluid inertia, 

driving pressures, elasticity, chaos.

# gst: period-doubling route to chaos in viscoelastic flows

<< Polymer solutions can develop chaotic flows, even at low inertia. This purely elastic turbulence is well studied, but little is known about the transition to chaos. In two-dimensional (2D) channel flow and parallel shear flow, traveling wave solutions involving coherent structures are present for sufficiently large fluid elasticity. >>

AA << numerically study 2D periodic parallel shear flow in viscoelastic fluids, and (They) show that these traveling waves become oscillatory and undergo a series of period-doubling bifurcations en-route to chaos. >>

Jeffrey Nichols, Robert D. Guy, Becca Thomases. Period-doubling route to chaos in viscoelastic Kolmogorov flow. Phys. Rev. Fluids 10, L041301. Apr 17, 2025.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.10.L041301

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

Keywords: gst, chaos, waves, traveling waves, elasticity, viscoelastic fluids, turbulence, elastic turbulence, period-doubling bifurcations, transitions

# gst: elastic instability of wormlike micelle solution flow in serpentine channels

AA << investigated the flow behavior of a highly elastic, shear-thinning, semi-dilute (Wormlike micelle) WLM solution in serpentine channels at low Reynolds number and moderate Weissenberg numbers. >>

Their << flow visualization experiments revealed three key phenomena: >>

1. << At low Wi, the base flow is steady and laminar but exhibits spatial asymmetry with wall slip, reflecting the shear-thinning and shear banding properties of the WLM solution. Above a critical Wi (..) the flow undergoes an elastic instability and transitions to a 3D unsteady flow state characterized by pronounced spatiotemporal velocity fluctuations. (..). >>

2. << Alongside this unstable bulk flow, dead zones of stagnant fluid form in the downstream portion of halfloops—reflecting the ability of the WLM solution to support shear localization, complementing reports of dead zone formation for other types of complex fluids (..). Due to coupling to the velocity fluctuations in the bulk flow, these dead zones fluctuate in their size; however, they are bounded by a maximalsize that minimizes the fluid streamline curvature, and therefore the generation of elastic stresses. Dead zones also exhibit multistable behavior—forming and persisting in some half-loops, not forming in other half-loops, and randomly switching between these two states. (..). >>

3. << The unstable flow state also features intermittent, 3D “twisting” velocity inversion events amid the spatiotemporally-fluctuating bulk flow. These twisting events reduce the hydrodynamic tortuosity compared to the base flow state, and their geometric structure can also be rationalized as minimizing the fluid streamline curvature, and therefore the generation of elastic stresses. >>

Emily Y. Chen, Sujit S. Datta. Elastic instability of wormlike micelle solution flow in serpentine channels. arXiv: 2504.02951v1 [physics.flu-dyn]. 

https://arxiv.org/abs/2504.02951

Also: elastic, instability, disorder & fluctuations, transition, behav, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, elasticity, instability, disorder & fluctuations, transition, behavior, multistable behavior, randomly switch, twisting events, dead zone

# gst: asymptotic scaling in a one-dimensional billiard

<< The emergence of power laws that govern the large-time dynamics of a one-dimensional billiard of N point particles is analysed. In the initial state, the resting particles are placed in the positive half-line x≥0 at equal distances. Their masses alternate between two distinct values. The dynamics is initialized by giving the leftmost particle a positive velocity. >>

<< Due to elastic inter-particle collisions the whole system gradually comes into motion, filling both right and left half-lines. As shown by S. Chakraborti, et al. (2022), an inherent feature of such a billiard is the emergence of two different modes: the shock wave that propagates in x≥0 and the splash region in x<0. >>

<< Moreover, the behaviour of the relevant observables is characterized by universal asymptotic power-law dependencies. In view of the finite size of the system and of finite observation times, these dependencies only start to acquire a universal character. To analyse them, (AA) set up molecular dynamics simulations using the concept of effective scaling exponents, familiar in the theory of continuous phase transitions. (They) present results for the effective exponents that govern the large-time behaviour of the shock-wave front, the number of collisions, the energies and momentum of different modes and analyse their tendency to approach corresponding universal values. >>️

<< A characteristic feature of the billiard problem (AA) have considered (..) is the lack of a priori randomness, neither in the distribution of masses nor in the inter-particle distances. Therefore, the emergence of the hydrodynamic power-law asymptotics– pointing to the stochastic background of the underlying process– may be interpreted as a kind of self-averaging in the system.  >>️

Taras Holovatch, Yuri Kozitsky, et al. Effective and asymptotic scaling in a one-dimensional billiard problem. arXiv: 2503.20476v1 [cond-mat.stat-mech]. Mar 26, 2025.

https://arxiv.org/abs/2503.20476

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

Keywords: gst, billiard, randomness 

# gst: odd electrical circuits

<< Non-reciprocal interactions in elastic media give rise to rich non-equilibrium behaviors, but controllable experimental realizations of such odd elastic phenomena remain scarce. Building on recent breakthroughs in electrical analogs of non-Hermitian solid-state systems, (AA) design and analyze scalable odd electrical circuits (OECs) as exact analogs of an odd solid. >>

AA << show that electrical work can be extracted from OECs via cyclic excitations and trace the apparent energy gain back to active circuit elements. (They) show that OECs host oscillatory modes that resemble recent experimental observations in living chiral crystals and identify active resonances that reveal a perspective on odd elasticity as a mechanism for mechanical amplification. >>️

Harry Walden, Alexander Stegmaier, et al. Odd electrical circuits. arXiv: 2503.14383v1 [cond-mat.soft]. Mar 18, 2025.

https://arxiv.org/abs/2503.14383

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

Keywords: gst, chirality, chiral crystals, chiral oscillations, chiral waves, oddity, odd elastic materials

# gst: dynamics of fluid-driven fractures across material heterogeneities.

<< Fracture propagation is highly sensitive to the conditions at the crack tip. In heterogeneous materials, microscale obstacles can cause propagation instabilities. Macroscopic heterogeneities modify the stress field over scales larger than the tip region. >>

 Here AA << experimentally investigate the propagation of fluid-driven fractures through multilayered materials. (They) focus on analyzing fracture profiles formed upon injection of a low-viscosity fluid into a two-layer hydrogel block. >>

<< Experimental observations highlight the influence of the originating layer on fracture dynamics. Fractures that form in the softer layer are confined, with no penetration in the stiffer layer. Conversely, fractures initiated within the stiffer layer experience rapid fluid transfer into the softer layer when reaching the interface. >>

AA << report the propagation dynamics and show that it is controlled by the toughness contrast between neighboring layers, which drives fluid flow. (They) model the coupling between elastic deformation, material toughness, and volume conservation. After a short transient regime, scaling arguments capture the dependence of the fracture geometry on material properties, injection parameters, and time. These results show that stiffness contrast can modify fracture propagation over large length scales and demonstrate the importance of macroscopic scale heterogeneities on fracture dynamics. >>

Sri Savya Tanikella, Marie C. Sigallon, Emilie Dressaire. Dynamics of fluid-driven fractures across material heterogeneities. Phys. Rev. E 111, 025504. Feb 28, 2025.   https://journals.aps.org/pre/abstract/10.1103/PhysRevE.111.025504     arXiv: 2407.10298v1 [physics.flu-dyn]. Jul 14, 2024.  https://arxiv.org/abs/2407.10298

Also: fracture, crack, elastic, 

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

Keywords: gst, fracture, crack, elasticity, instability, disorder, transitions

# gst: 'jazzy' intermittency, its onset and multiscaling in active turbulence.

<< Recent results suggest that highly active, chaotic, nonequilibrium states of living fluids might share much in common with high Reynolds number, inertial turbulence. (AA) now show, by using a hydrodynamical model, the onset of intermittency and the consequent multiscaling of Eulerian and Lagrangian structure functions as a function of the bacterial activity. (Their) results bridge the worlds of low and high Reynolds number flows as well as open up intriguing possibilities of what makes flows intermittent. >>️

AA << believe that (Their) work significantly understands the dynamics of dense bacterial suspensions in ways which isolates the truly turbulent effects from those stemming from simpler chaotic motion. More intriguingly, and at a broader conceptual framework, this study yet again underlines that intermittency can be an emergent phenomena in flows where the nonlinearity does not, trivially, dominate the viscous damping. Indeed, there is increasing evidence of intermittency emerging in systems which are not turbulent in the classical sense. Examples include flows with modest Reynolds number of∼O(10e2) showing intermittent behaviour characteristic of high Reynolds turbulence, self-propelling active droplets with intermittent fluctuations, active matter systems of self-propelled particles, which undergo a glass transition, with an intermittent phase before dynamical arrest, and perhaps most pertinently, in elastic turbulence. Thus, (AA) believe, (Their) work will contribute further to understanding what causes flows to turn intermittent. Answers to such questions will also help in understanding fundamental questions in high Reynolds number turbulence. >>️

Kolluru Venkata Kiran, Kunal Kumar, et al. Onset of Intermittency and Multiscaling in Active Turbulence. Phys. Rev. Lett. 134, 088302. Feb 28, 2025. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.134.088302  arXiv: 2408.06950v2 [cond-mat.soft].  https://arxiv.org/abs/2408.06950

Also: intermittency, transition, fluctuations, drop, droplet, droploid, elastic, turbulence, chaos, jazz, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, intermittency, transitions, fluctuations, drops, droplets, droploids, elasticity, turbulence, chaos, jazz