# gst: stochastic surfing turbulent vorticity.

<< The chaotic dynamics of small-scale vorticity plays a key role in understanding and controlling turbulence, with direct implications for energy transfer, mixing, and coherent structure evolution. >>

Here AA << use a combination of experiments, theory and simulations to show that small magnetic particles of different densities, exploring flow regions of distinct vorticity statistics, can act as effective probes for measuring and forcing turbulence at its smallest scale. The interplay between the magnetic torque, from an externally controllable magnetic field, and hydrodynamic stresses, from small-scale turbulent vorticity, reveals an extremely rich phenomenology. >>

Notably, AA << present the first observation of stochastic resonance for particles in turbulence: turbulent fluctuations, effectively acting as noise, counterintuitively enhance the particle rotational response to external forcing. (They) identify a pronounced resonant peak in particle rotational phase-lag when the applied magnetic field matches the characteristic intensity of small-scale vortices. >>

<< Furthermore, (They) uncover a novel symmetry-breaking mechanism: an oscillating magnetic field with zero-mean angular velocity remarkably induces net particle rotation in turbulence with zero-mean vorticity, as turbulent fluctuations aid the particle in "surfing" the magnetic field. >>

Ziqi Wang, Xander M. de Wit, et al. Stochastic surfing turbulent vorticity. arXiv: 2504.08346v1 [physics.flu-dyn]. Apr 11, 2025. 

https://arxiv.org/abs/2504.08346

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

Keywords: gst, vortices, turbulence, turbulent fluctuations, small-scale turbulent vorticity, stochastic resonance, noise, transitions 

# gst: statistical mechanics of frustrated assemblies and incompatible graphs

<< Geometrically frustrated assemblies where building blocks misfit have been shown to generate intriguing phenomena from self-limited growth, fiber formation, to structural complexity. >>  

AA << introduce a graph theory formulation of geometrically frustrated assemblies, capturing frustrated interactions through the concept of incompatible flows, providing a direct link between structural connectivity and frustration. This theory offers a minimal yet comprehensive framework for the fundamental statistical mechanics of frustrated assemblies, and connects it to tensor gauge theory formulations of amorphous solids. >>

<< Through numerical simulations, the theory reveals new characteristics of frustrated assemblies, including two distinct percolation transitions for structure and incompatible flows, a crossover between cumulative and noncumulative frustration controlled by disorder, and a divergent length scale in their response. >>

José M. Ortiz-Tavárez, Zhen Yang, et al. Statistical Mechanics of Frustrated Assemblies and Incompatible Graphs. Phys. Rev. Lett. 134, 147401. Apr 7, 2025. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.134.147401

arXiv: 2407.18210v1 [cond-mat.soft]. Thu, 25 Jul 2024.

https://arxiv.org/abs/2407.18210 

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

Keywords: gst, disorder, transitions, percolation transitions, frustration, frustrated assemblies 

# gst: strange attractors in complex networks

<< Disorder and noise in physical systems often disrupt spatial and temporal regularity, yet chaotic systems reveal how order can emerge from unpredictable behavior. Complex networks, spatial analogs of chaos, exhibit disordered, non-Euclidean architectures with hidden symmetries, hinting at spontaneous order. Finding low-dimensional embeddings that reveal network patterns and link them to dimensionality that governs universal behavior remains a fundamental open challenge, as it needs to bridge the gap between microscopic disorder and macroscopic regularities. >>

<< Here, the minimal space revealing key network properties is introduced, showing that non-integer dimensions produce chaotic-like attractors. >>

Pablo Villegas. Strange attractors in complex networks. Phys. Rev. E 111, L042301. Apr 15, 2025. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.111.L042301.  

arXiv: 2504.08629v1 [cond-mat.stat-mech] . Apr 11, 2025.

https://arxiv.org/abs/2504.08629

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

Keywords: gst, disorder, disorder & fluctuations, noise, networks, attractors, self-similarity, chaos 

# gst: weird quasiperiodic attractors

AA << consider a class of n-dimensional, n≥2, piecewise linear discontinuous maps that can exhibit a new type of attractor, called a weird quasiperiodic attractor. While the dynamics associated with these attractors may appear chaotic, (They)  prove that chaos cannot occur. The considered class of n-dimensional maps allows for any finite number of partitions, separated by various types of discontinuity sets. The key characteristic, beyond discontinuity, is that all functions defining the map have the same real fixed point. These maps cannot have hyperbolic cycles other than the fixed point itself. >>

Laura Gardini, Davide Radi, et al. Abundance of weird quasiperiodic attractors in piecewise linear discontinuous maps. arXiv: 2504.04778v1 [math.DS]. Apr 7, 2025.

https://arxiv.org/abs/2504.04778

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

Keywords: gst, attractors, weird attractors, chaos

# 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: apropos of drift-waves, their coherent puff and slugs in transitional turbulence.

<< The long-term development of the transitional regime of drift-wave turbulence is studied in a magnetized plasma column by means of the conditional-average technique. >>

<< In the transitional regime, small changes in the magnetic-field strength as control parameter lead to large changes in the correlation times, indicating the existence of a critical point of an underlying nonequilibrium continuous phase transition. >>

<< This and the spatiotemporal dynamics shows similarities to puff splitting, slug-gap splitting, and puff jamming. >>️

P. Manz, S. Knauer, et al. Coherent puff and slugs in transitional drift-wave turbulence. Phys. Rev. E 111, 045203. April 8, 2025.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.111.045203

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

Keywords: gst, waves, drift-waves, turbulence, jamming, transition, puff splitting, slug-gap splitting, puff jamming 

# gst: experimental investigation of turbulence modulation by deformable bubbles

<< In this work (AA) experimentally investigate the turbulence modulation in the wake of deforming bubbles in homogeneous and isotropic turbulence, in the regime where the turbulence fluctuation is stronger than or comparable to the bubble rising velocity. >>

<< In a quiescent or weak turbulence, the wake has a persistent direction due to the buoyancy. In turbulence, however, (Their) results suggest that the decorrelation time for the slip velocity roughly equals the bubble-sized eddy turn over time. It suggests that, when turbulence becomes intense enough, the slip velocity changes its direction and magnitude so frequently that a wake barely has time to develop. >>

<< As a result, both the intensity and length of the wake are significantly modified. Nevertheless, with sufficient bubble Reynolds number, the wake, albeit limited, can still modulate surrounding turbulence. >>

<< The results suggest that the local turbulence is augmented by the bubble wake, and the amount of augmentation depends heavily on the bubble Reynolds number, the orientation of the bubble semimajor axis relative to the slip velocity, and the bubble deformation. >>️

Xu Xu, Shiyong Tan, et al. Experimental investigation of turbulence modulation by deformable bubbles. Phys. Rev. Fluids 10, 033605. March 31, 2025.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.10.033605

Also: bubble, disorder & fluctuations, turbulence, vortex, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, bubble, deformable bubbles, bubble wake, bubble-bubble interaction, disorder & fluctuations, turbulence, turbulence modulation, surrounding turbulence, vortex, slip velocity, buoyancy