Phase transitions at fluid interfaces and in fluids confined pores have been investigated by means of a density functional approach that treats attractive forces between molecules mean-field approximation models repulsive hard-spheres. Two types were employed for the hard-sphere free energy functional: (a) well-known local (LDA) omits short-ranged correlations (b) non-local smoothed (SDA) includes such therefore accounts oscillations profile near walls. Three different kinds phase transition...

By means of a density functional approach the phase equilibria simple fluid confined by two adsorbing walls have been investigated as function wall separation H and chemical potential μ for temperature T corresponding to both partial complete wetting situations. For large values small undersaturations Δμ ≡ μsat−μ, we recover macroscopic formulas undersaturation at which first- order transition (capillary condensation) from dilute ‘‘gas’’ dense ‘‘liquid’’ occurs in single, infinitely long...

The nature of adsorption simple fluids confined in model pores is investigated by means a density functional approach. For temperatures T corresponding to partial wetting situation first-order phase transition (capillary condensation) from dilute ‘gas’ dense ‘liquid’ occurs at relative pressures p/psat close those predicted the macroscopic Kelvin equation, even for radii Rc or wall separations H as small 10 molecular diameters. In complete situation, where thick films develop, equation is,...

Abstract We derive the stationary probability distribution for a non-equilibrium system composed by an arbitrary number of degrees freedom that are subject to Gaussian colored noise and conservative potential. This is based on multidimensional version Unified Colored Noise Approximation. By comparing theory with numerical simulations we demonstrate theoretical density quantitatively describes accumulation active particles around repulsive obstacles. In particular, two interactions, close...

We study a system of purely repulsive spherical self-propelled particles in the minimal setup inducing motility-induced phase separation (MIPS). show that, even if explicit alignment interactions are absent, growing order velocities clustered accompanies MIPS. Particles arrange into aligned or vortexlike domains whose size increases as persistence self-propulsion grows, an effect that is quantified studying spatial correlation function velocities. explain velocity by unveiling hidden...

We present a new time-dependent density functional approach to study the relaxational dynamics of an assembly interacting particles subject thermal noise. Starting from Langevin stochastic equations motion for velocities we are able by means approximated closure derive self-consistent deterministic equation temporal evolution average particle density. The is equivalent assuming that equal-time two-point correlation function out equilibrium has same properties as its version. changes in time...

The thermodynamics of fluids confined between two adsorbing solid substrates (walls) is revisited. Attention focused on the phase equilibria an open system characterized by variables μ (chemical potential), T (temperature), and H (wall separation). Clapeyron equations for shape lines coexistence are derived used to interpret results earlier calculations first-order transitions, namely capillary condensation undersaturated ‘‘gas’’ ‘‘liquid’’ prewetting (thick–thin film transition) at finite...

We present adsorption isotherms, phase diagrams, and density profiles for a Lennard-Jones fluid confined to cylindrical pore. In particular, we concentrate on the gas–liquid transition in pore (capillary condensation). compare simulations series of radii different temperatures with mean field functional theory (MFT). Two forms MFT are considered, simple local approximation (LDA) Tarazona’s nonlocal or smoothed (SDA). find that SDA provides quite accurate description structure it produces...

We present a new time-dependent density functional approach for studying the relaxational dynamics of an assembly interacting particles, subject to thermal noise. Starting from Langevin stochastic equations motion velocities we are able by means approximate closure derive self-consistent deterministic equation temporal evolution average particle density. The is equivalent assuming that equal-time two-point correlation function out equilibrium has same properties as its version. changes over...

We investigate the properties of a model granular matter consisting $N$ Brownian particles on line, subject to inelastic mutual collisions. This displays genuine thermodynamic limit for mean values energy, and energy dissipation. When typical relaxation time $\ensuremath{\tau}$ associated with process is small compared collision ${\ensuremath{\tau}}_{c}$ spatial density nearly homogeneous velocity probability distribution Gaussian. In opposite...

We present a stochastic description of model <italic>N</italic> mutually interacting active particles in the presence external fields and characterize its steady state behavior absence currents.

We consider the effect of geometric confinement on steady-state properties a one-dimensional active suspension subject to thermal noise. The random force is modeled by an Ornstein-Uhlenbeck process and system studied both numerically, integrating Langevin governing equations, analytically solving associated Fokker-Planck equation under suitable approximations. comparison between two approaches displays fairly good agreement in particular, we show that approach can predict structure wall...

The present paper studies the spontaneous velocity alignment and time-intermittency of kinetic-energy in dense phases active matter. dynamical properties are described by considering spatial correlations constructing a non-equilibrium phase diagram force density which explores homogeneous inhomogeneous

The velocity field of systems active Brownian particles at high density shows large spatial coherent structures, a genuine non-equilibrium behavior. effects Peclet number, inertia and thermal diffusion on the ordering phenomenon are studied.

In this work, we study the stationary behavior of an assembly independent chiral active particles under confinement by employing extension Ornstein–Uhlenbeck model.

Abstract We derive an analytic expression for the distribution of velocities multiple interacting active particles which we test by numerical simulations. In clear contrast with equilibrium find that are coupled to positions. Our model shows that, even two only, individual display a variance depending on interparticle separation and emergence correlations between particles. When considering systems composed many connecting overall velocity density, at mean-field level, pair function valid in...

Abstract Methods of stochastic thermodynamics and hydrodynamics are applied to a recently introduced model active particles. The consists an overdamped particle subject Gaussian coloured noise. Inspired by thermodynamics, we derive from the system’s Fokker-Planck equation average exchanges heat work with bath associated entropy production. We show that Clausius inequality holds, local (non-uniform) temperature replacing uniform usually encountered in equilibrium systems. Furthermore,...

We study a system of non-interacting active particles, propelled by colored noises, characterized an activity time τ, and confined double-well potential. A straightforward application this is the problem barrier crossing which has been studied only in limit small activity. When τ sufficiently large, equilibrium-like approximations break down region. In model under investigation, it emerges as sort "negative temperature" region, numerical simulations confirm presence non-convex local velocity...

The equations of motion active systems can be modeled in terms Ornstein-Uhlenbeck processes (OUPs) with appropriate correlators. For further theoretical studies, these should approximated to yield a Markovian picture for the dynamics and simplified steady-state condition. We perform comparative study Unified Colored Noise Approximation (UCNA) approximation scheme by Fox recently employed within this context. review approximations necessary define effective interaction potentials low-density...

We study the dynamical properties of an active particle subject to a swimming speed explicitly depending on position. The oscillating spatial profile swim velocity considered in this paper takes inspiration from experimental studies based Janus particles whose can be modulated by external source light. suggest and apply appropriate model Ornstein Uhlenbeck (AOUP) present case. This allows us predict stationary properties, finding exact solution steady-state probability distribution position...

The vibrational dynamics of solids is described by phonons constituting basic collective excitations in equilibrium crystals. Here, we consider a non-equilibrium active solid, formed self-propelled particles, which bring the system into steady-state. We identify novel (active) origin, coexist with and dominate over them when far from equilibrium. These are interpreted framework physics, particular, stochastic thermodynamics. call “entropons” because they modes spectral entropy production (at...

We address the problem of so-called "granular gases," i.e., gases massive particles in rapid movement undergoing inelastic collisions. introduce a class models driven granular for which stationary state is result balance between dissipation and random forces inject energies. These exhibit genuine thermodynamic limit, at fixed density mean values kinetic energy dissipated per particle are independent number N particles, large N. One has two regimes: when typical relaxation time tau driving...

We report a study of hard-sphere mixtures different sizes near hard wall using both the Monte Carlo method and density functional theory. The theory is based on semiempirical free-energy for an inhomogeneous mixture similar to that developed by Tarazona pure fluids. Comparison between theoretical results simulations profiles species mole fraction profile shows present capable describing structure against up size ratio, R≡σ2/σ1, about 3. For R values greater than 3 gives some discrepancies...