scholarly journals Aggregation dynamics of active rotating particles in dense passive media

Soft Matter ◽  
2019 ◽  
Vol 15 (19) ◽  
pp. 3929-3937 ◽  
Author(s):  
Juan L. Aragones ◽  
Joshua P. Steimel ◽  
Alfredo Alexander-Katz
Keyword(s):  
Active Matter ◽  
Effective Interactions ◽  
Equilibrium Behavior ◽  
Active Particles ◽  
Non Equilibrium

Active matter systems are able to exhibit emergent non-equilibrium behavior due to activity-induced effective interactions between the active particles.

Shock discontinuity zone effect: the main factor in the explosive decomposition detonation process

1992 ◽  
Vol 339 (1654) ◽  
pp. 355-364 ◽  
Keyword(s):  
Degrees Of Freedom ◽  
Thermal Ionization ◽  
Relaxation Processes ◽  
Explosive Decomposition ◽  
Time Duration ◽  
Active Particles ◽  
Condensed Explosives ◽  
Discontinuity Zone ◽  
Electronically Excited ◽  
Non Equilibrium

A new qualitative conception of the detonation mechanism in condensed explosives has been developed on the basis of experimental and numerical modelling data. According to the conception the mechanism consists of two stages: non-equilibrium and equilibrium. The mechanism regularities are explosive characteristics and they do not depend on explosive charge structure (particle size, nature of filler in the pores, explosive state, liquid or solid, and so on). The tremendous rate of loading inside the detonation wave shock discontinuity zone ( ca. 10 -13 s) is responsible for the origin of the non-equilibrium stage. For this reason, the kinetic part of the shock compression energy is initially absorbed only by the translational degrees of freedom of the explosive molecules. It involves the appearance of extremely high translational temperatures for the polyatomic molecules. In the course of the translational-vibrational relaxation processes (that is, during the first non-equilibrium stage of ca. 10 -10 s time duration) the most rapidly excited vibrational degrees of freedom can accumulate surplus energy, and the corresponding bonds decompose faster than behind the front at the equilibrium stage. In addition to this process, the explosive molecules become electronically excited and thermal ionization becomes possible inside the translational temperature overheat zone. The molecules thermal decomposition as well as their electronic excitation and thermal ionization result in some active particles (radicals, ions) being created. The active particles and excited molecules govern the explosive detonation decomposition process behind the shock front during the second equilibrium stage. The activation energy is usually low, so that during this stage the decomposition proceeds extremely rapidly. Therefore the experimentally observed dependence of the detonation decomposition time for condensed explosives is rather weak.

Active Particle Diffusion in Convection Roll Arrays

2021 ◽  
Author(s):  
Pulak Kumar Ghosh ◽  
Fabio Marchesoni ◽  
Yunyun Li ◽  
Franco Nori
Keyword(s):  
Active Particle ◽  
Particle Diffusion ◽  
Active Matter ◽  
Active Particles ◽  
Convection Roll ◽  
Small Scales

Undesired advection effects are unavoidable in most nano-technological applications involving active matter. However, it is conceivable to govern the transport of active particles at the small scales by suitably tuning...

scholarly journals Oscillating collective motion of active rotors in confinement

2020 ◽  
Vol 117 (22) ◽  
pp. 11901-11907 ◽  
Author(s):  
Peng Liu ◽  
Hongwei Zhu ◽  
Ying Zeng ◽  
Guangle Du ◽  
Luhui Ning ◽  
...  
Keyword(s):  
Collective Behavior ◽  
Collective Motion ◽  
Dynamic Structure ◽  
Packing Fraction ◽  
Frictional Stress ◽  
Active Matter ◽  
Active Particles ◽  
Particle Level ◽  
Inhomogeneous Density ◽  
Oscillation Properties

Due to its inherent out-of-equilibrium nature, active matter in confinement may exhibit collective behavior absent in unconfined systems. Extensive studies have indicated that hydrodynamic or steric interactions between active particles and boundary play an important role in the emergence of collective behavior. However, besides introducing external couplings at the single-particle level, the confinement also induces an inhomogeneous density distribution due to particle-position correlations, whose effect on collective behavior remains unclear. Here, we investigate this effect in a minimal chiral active matter composed of self-spinning rotors through simulation, experiment, and theory. We find that the density inhomogeneity leads to a position-dependent frictional stress that results from interrotor friction and couples the spin to the translation of the particles, which can then drive a striking spatially oscillating collective motion of the chiral active matter along the confinement boundary. Moreover, depending on the oscillation properties, the collective behavior has three different modes as the packing fraction varies. The structural origins of the transitions between the different modes are well identified by the percolation of solid-like regions or the occurrence of defect-induced particle rearrangement. Our results thus show that the confinement-induced inhomogeneity, dynamic structure, and compressibility have significant influences on collective behavior of active matter and should be properly taken into account.

Dry Aligning Dilute Active Matter

2020 ◽  
Vol 11 (1) ◽  
pp. 189-212 ◽  
Author(s):  
Hugues Chaté
Keyword(s):  
Long Range ◽  
Collective Motion ◽  
Local Level ◽  
Orientational Order ◽  
Two Dimensions ◽  
Active Matter ◽  
Long Range Correlations ◽  
Active Particles ◽  
Growing Domain

Active matter physics is about systems in which energy is dissipated at some local level to produce work. This is a generic situation, particularly in the living world but not only. What is at stake is the understanding of the fascinating, sometimes counterintuitive, emerging phenomena observed, from collective motion in animal groups to in vitro dynamical self-organization of motor proteins and biofilaments. Dry aligning dilute active matter (DADAM) is a corner of the multidimensional, fast-growing domain of active matter that has both historical and theoretical importance for the entire field. This restrictive setting only involves self-propulsion/activity, alignment, and noise, yet unexpected collective properties can emerge from it. This review provides a personal but synthetic and coherent overview of DADAM, focusing on the collective-level phenomenology of simple active particle models representing basic classes of systems and on the solutions of the continuous hydrodynamic theories that can be derived from them. The obvious fact that orientational order is advected by the aligning active particles at play is shown to be at the root of the most striking properties of DADAM systems: ( a) direct transitions to orientational order are not observed; ( b) instead generic phase separation occurs with a coexistence phase involving inhomogeneous nonlinear structures; ( c) orientational order, which can be long range even in two dimensions, is accompanied by long-range correlations and anomalous fluctuations; ( d) defects are not point-like, topologically bound objects.

Non-equilibrium behavior of small carbohydrate-water systems

1988 ◽  
Vol 60 (12) ◽  
pp. 1841-1864 ◽  
Author(s):  
L. Slade ◽  
Harry Levine
Keyword(s):  
Water Systems ◽  
Equilibrium Behavior ◽  
Non Equilibrium
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