Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session X17: Non-Linear Dynamics and Pattern FormationLive
|
Hide Abstracts |
Sponsoring Units: GSNP Chair: Thomas Witten, University of Chicago |
Friday, March 19, 2021 8:00AM - 8:12AM Live |
X17.00001: Structure of Fluctuating Thin Sheets Under Random Forcing Chanania Steinbock, Eytan Katzav, Arezki Boudaoud Research from both wave turbulence [1] and the physics of crumpled paper [2] has made it clear that understanding the spectra of deformations of thin sheets is crucial to understanding their structural and dynamic properties. The Föppl-von Kármán (FvK) equations which describe such deformations however have long been recognised as extremely challenging to solve. Here, we argue for a noisy over-damped FvK equation, in which a conserved random force keeps a fluctuating thin sheet out of equilibrium. By applying a novel method known as the Self-Consistent Expansion, a method which both borrows from and extends the renormalisation group, we have been able to obtain a concise integral equation for the two-point function of the deformations of such thin sheets. Surprisingly, this integral equation is amenable to analytic methods and provides precise analytic predictions. Of particular note is that unlike previous claims [3], we find that no exotic roughness exponents are needed to characterise the spectrum, rather, simple rational functions suffice. Simulations further confirm the validity of our solution. |
Friday, March 19, 2021 8:12AM - 8:24AM Live |
X17.00002: Post-buckling of hyperelastic thick tube under axial compression Yu Zhou, Yuzhen Chen, Lihua Jin In recent years, mechanical instabilities of soft materials have been substantially investigated and utilized. Though tube structures are widely used and instabilities of thin-walled tubes are well studied, postbuckling behavior of hyperelastic thick tubes is elusive. In this presentation, we conduct buckling and postbuckling analysis for hyperelastic thick tubes undergoing finite deformation. We will briefly introduce the asymptotic expansion method for buckling and weakly postbuckling of elastic bodies and apply this theory to thick tubes. Our analytical results are validated by finite element simulations. As a result, a long tube prefers the Euler buckling mode, while a short tube prefers the barreling mode. Depending on the geometry, three kinds of postbuckling paths, including increasing force, snap-through and snap-back, are discovered. We summarize our results in two phase diagrams of buckling and postbuckling with respect to geometric parameters, which provide guidelines for utilization of tube structures. |
Friday, March 19, 2021 8:24AM - 8:36AM Live |
X17.00003: Straight-to-curvilinear motion transition of a swimming droplet driven by the Marangoni effect Saori Suda, Tomoharu Suda, Takuya Ohmura, Masatoshi Ichikawa The swimming microdroplet is a simple experimental model of active matter. When water microdroplets are introduced into an oil-surfactant solution, the Marangoni effect causes convection on the droplets' surfaces and induces the self-propelled motions of the droplets [1]. The variety of observed motions makes the experimental system interesting as an example of nonequilibrium phenomena of fluid dynamics and simultaneously attractive as a real space model of actively swimming objects such as swimming microorganisms. In this study, we measured swimming microdroplets' motion to identify the straight-to-curvilinear motion transition, one of the fundamental transitions observed in the self-propelled motion. We found that the transition occurs as the droplet size increases. To elucidate the mechanism behind this phenomenon, we developed a three-dimensional theoretical model based on the advection-diffusion and Stokes equations combined by the surface tension distribution. The model explains the results of the experiments and reveals the characteristics of the transition. |
Friday, March 19, 2021 8:36AM - 8:48AM Live |
X17.00004: A direct Thermoelectric Energy Conversion of a Drinking Bird Motion Hiroshi Uechi A drinking bird (DB) also known as a dipping bird is an interesting and amusing toy, swinging back-and-forth like a simple pendulum. We discuss a technique to extract electric energy from the DB’s motion, which is termed as thermoelectric energy generation (TEG) technique by employing solutions of a thermomechanical model of a drinking bird (DB) [1]. |
Friday, March 19, 2021 8:48AM - 9:00AM Live |
X17.00005: Dendritic crystal growth: A comparison of ammonium nitrate and ammonium chloride Andrew Dougherty Dendritic crystal growth is an important example of nonequilibrium pattern formation that involves both nonlinear and noise-driven effects. It is commonly observed in the growth of metal alloys, but can also be observed in the solidification of some transparent organic and inorganic compounds. The resulting large-scale structures are sensitively dependent on relatively small effects, such as surface tension, and on small anisotropies in those quantities. In this work, we present results for ammonium chloride dendrites and compare them with new results for ammonium nitrate dendrites grown from supersaturated aqueous solution. This new system has been studied previously by van Driel et al.[1]. Specifically, we present new measurements of the tip radius ρ, growth speed v, and sidebranch spacing λ, along with initial estimates of the product Dd0, where D is the chemical diffusion constant and d0 is the capillary length. We also present new estimates of the stability constant σ*=2d0D/vρ2, and discuss similarities and differences between the two materials. |
Friday, March 19, 2021 9:00AM - 9:12AM Live |
X17.00006: Competing for Resources: on the Emergence of Property Rights Clelia De Mulatier, Cristina Pinneri, Vijay Balasubramanian, Matteo Marsili A game theory approach to the evolution of animal conflicts has shown that choosing an initial asymmetric feature, such as first come first served, to settle a contest is evolutionarily stable, as it avoids the costs of animal fights. In this context, we investigate the optimal strategies of a population of non-aggressive agents competing for multiple resources. Resources provide different payoffs and can only be exploited by one agent at a time. If an agent tries a resource that turns out to be occupied, it then looks for another resource, which has a cost. We show theoretically and numerically that this system admits two types of Nash equilibria. In an under-crowded system, resources are equally shared between agents; our reinforcement learning simulations find multiple optimal solutions, where agents each exploit different sets of resources but all earn the same average payoff. The average strategy of these agents matches with the theoretical mean-field solution. Over-crowded systems are instead conducive to the emergence of inequality; some agents can earn more than the others by establishing themselves as property owners of a medium-payoff resource. In the reinforcement learning simulations, such lucky agents emerge naturally from their random learning experience. |
Friday, March 19, 2021 9:12AM - 9:24AM Live |
X17.00007: Levitated nanoparticles as non-equilibrium memories: experimental verification of the generalised Landauer’s principle Mario Arnolfo Ciampini, Tobias Wenzl, Michael Konopik, Eric Lutz, Gregor Thalhammer, Monika Ritsch-Marte, Markus Aspelmeyer, Nikolai Kiesel Optical levitation of nanoscale particles promises to become an outstanding platform for experiments in force sensing and in the foundations of quantum physics and stochastic thermodynamics. Most of the experiments till now, however, have hardly made use of the extraordinary versatility of optical micromanipulation technology. Here, we present a novel optical holographic, SLM enabled, trapping platform that levitates a nanosphere in vacuum in a fully controllable double-well potential. |
Friday, March 19, 2021 9:24AM - 9:36AM Live |
X17.00008: A reduced Föppl–von Kármán model for magnetic plates Dong Yan, Arefeh Abbasi, Pedro M Reis Slender plate-like structural elements are widely employed in both traditional engineering structures and advanced functional devices. Their counterparts made of magnetically-active materials can provide fast and reversible shape-morphing through contactless remote actuation. Several promising applications involving magnetic plates have been recently proposed in the literature, albeit with designs that have been primarily driven by intuition. As such, there is a striking lack of formal theoretical tools to aid in the predictive and rational design of this class of magneto-elastic slender structures. Here, we develop a 2D theory for the mechanics of thin hard-magnetic plates. Following a dimensional reduction procedure akin to that of classic Föppl–von Kármán plates, we reduce the system's 3D energy functional, including the magneto-elastic coupling, into a 2D description based on the plate's mid-surface. The equilibrium equations obtained through variational methods are then employed to predict the plate deformation under a combination of mechanical and magnetic loading conditions. We also analyze a magnetically-actuated buckling problem. Our theoretical framework for the mechanics of magnetic plates is validated thoroughly using experiments and full 3D finite element modeling. |
Friday, March 19, 2021 9:36AM - 9:48AM Live |
X17.00009: Retarding Damages/Cracks via Auxetic effects and Snap-through Instability Yanzhang Xu, Yaning Li Damages/Cracks usually develop in materials under multi-axial loading. When initiated, damages/cracks often evolve rapidly, significantly reducing material load-bearing capability or leading to catastrophic failure. Retarding damages/cracks is the key to improve the mechanical performance of materials. In this investigation, a new concept of retarding damages/cracks via auxetic effects and snap-through instability is proposed. To prove the concept, new multi-phase composites with auxetic effects and snap-through-instability-induced negative stiffness are designed. Finite element models of the new designs are developed. Finite simulations of the new designed materials under both in-plane and out-of-plane loads are conducted. |
Friday, March 19, 2021 9:48AM - 10:00AM Live |
X17.00010: Translational and rotational dynamics of a self-propelled Janus probe in a crowded medium Ligesh Theeyancheri, Subhasish Chaki, Nairhita Samanta, Rohit Goswami, Raghunath Chelakkot, Rajarshi Chakrabarti Motivated by a series of experiments, we simulate the dynamics of a self-propelled (active) Janus probe in a crowded medium. The crowding is caused either by viscoelastic polymer chains or by non-viscoelastic spherical colloids. Our simulations show enhancement of the translational and rotational dynamics with the self-propulsion velocity but most importantly a three-step growth (diffusive-superdiffusive-diffusive) is also observed in the case of rotational motion of the self-propelled Janus, while crowders are present. This is observed irrespective of whether the crowders are viscoelastic or not, confirming viscoelasticity of the medium is not responsible for this enhanced dynamics, rather it is the presence of crowders. However, in the absence of crowders, rotational dynamics remain practically unaffected as the self-propulsion velocity is changed. At the intermediate area fraction of the crowders, translational and rotational motions of the self-propelled Janus get decoupled. Such decoupling is not observed if the Janus is passive. |
Friday, March 19, 2021 10:00AM - 10:12AM Live |
X17.00011: Single active particle engine utilizing a nonreciprocal coupling between particle position and self-propulsion Grzegorz Szamel A self-propelled particle is formally equivalent to a system consisting of two sub-systems interacting with their own heat reservoirs and coupled by a nonreciprocal (violating Newton's third law) interaction. We previously showed that this approach allows us to generalize stochastic thermodynamics to systems of active particles. Here we argue that the nonreciprocal coupling can be used to extract useful work from a single self-propelled particle maintained at constant temperature. We demonstrate one way to achieve this extraction, through manipulating correlations between the particle's position and self-propulsion using an externally controlled aligning interaction. We analyze quantitatively the work extracted and the power, and the efficiency of the resulting single active particle engine. |
Friday, March 19, 2021 10:12AM - 10:24AM Live |
X17.00012: Efficiency in competitive group foraging Farnaz Golnaraghi, Ajay Gopinathan Many animals such as albatrosses are known to exhibit foraging patterns where the distances they travel in a given direction are drawn from a heavy-tailed Levy distribution. Previous studies have shown under sparse resources, solitary foragers perform an optimally efficient search with Levy exponent equal to 2. However, in nature, there also exist situations where multiple foragers interact with each other either cooperatively or competitively. We develop a stochastic agent-based simulation that models competitive foraging. In our system, each forager has a territory with a certain size around itself which is not accessible by the others. Our results for various system sizes show that by increasing the size of the territory, and the number of agents, the efficiency of the search decreases, and the optimal Levy exponent shifts toward values larger than 2, indicating that more localized searches are more efficient in the presence of competition. In addition, we compare our analytical solution to the one for solitary foragers. Finally, we show that the variance among the efficiencies of the agents increases with increasing Levy exponent. Thus, by performing more localized searches, foragers might increase mean efficiency, but with the risk of increasing fluctuations in efficiency. |
Friday, March 19, 2021 10:24AM - 10:36AM On Demand |
X17.00013: Relationship between Schreiber's transfer entropy and Liang--Kleeman information flow from the perspective of stochastic thermodynamics Hirohito Kiwata The Schreiber's transfer entropy is an important index for investigating the causal relationship between random variables. The Liang--Kleeman information flow is another method to demonstrate the causality within dynamical systems. The Horowitz--Esposito information flow is introduced through stochastic thermodynamics. In this study, I elucidate the relationship between the Schreiber's transfer entropy and the Liang--Kleeman information flow through the Horowitz--Esposito information flow. I consider the case where the system changes according to the stochastic differential equation. It is found that the Liang--Kleeman and Horowitz--Esposito information flows differ by a term derived from the stochastic fluctuation. It is shown that the Schreiber's transfer entropy is not less than the Horowitz--Esposito information flow. This study helps to unify various indexes that determine the causal relationship between variables. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700