Results for "M. E. Cates"

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Diffusive transport without detailed balance in motile bacteria: Does microbiology need statistical physics?Aug 20 2012Microbiology is the science of microbes, particularly bacteria. Many bacteria are motile: they are capable of self-propulsion. Among these, a significant class execute so-called run-and-tumble motion: they follow a fairly straight path for a certain distance, ... More
Dynamics of Polydisperse Polymer MixturesApr 25 2002Oct 25 2002We develop a general analysis of the diffusive dynamics of polydisperse polymers in the presence of chemical potential gradients, within the context of the tube model (with all species entangled). We obtain a set of coupled dynamical equations for the ... More
Hydrodynamically interrupted droplet growth in scalar active matterJul 10 2019Suspensions of spherical active particles often show microphase separation. At a continuum level, coupling their scalar density to fluid flow, there are two distinct explanations. Each involves an effective interfacial tension: the first mechanical (causing ... More
Flow instabilities in complex fluids: Nonlinear rheology and slow relaxationsOct 28 2003We here present two simplified models aimed at describing the long-term, irregular behaviours observed in the rheological response of certain complex fluids, such as periodic oscillations or chaotic-like variations. Both models exploit the idea of having ... More
Swelling kinetics of the onion phaseSep 01 2000A theory is presented for the behavior of an array of multi-lamellar vesicles (the onion phase) upon addition of solvent. A unique feature of this system is the possibility to sustain pressure gradients by tension in the lamellae. Tension enables the ... More
Statistical Mechanics of Interacting Run-and-Tumble BacteriaMar 07 2008Aug 14 2008We consider self-propelled particles undergoing run-and-tumble dynamics (as exhibited by E. coli) in one dimension. Building on previous analyses at drift-diffusion level for the one-particle density, we add both interactions and noise, enabling discussion ... More
A practical density functional for polydisperse polymersApr 24 2001The Flory Huggins equation of state for monodisperse polymers can be turned into a density functional by adding a square gradient term, with a coefficient fixed by appeal to RPA (random phase approximation). We present instead a model nonlocal functional ... More
Tensorial Constitutive Models for Disordered Foams, Dense Emulsions, and other Soft Nonergodic MaterialsJul 04 2003In recent years, the paradigm of `soft glassy matter' has been used to describe diverse nonergodic materials exhibiting strong local disorder and slow mesoscopic rearrangement. As so far formulated, however, the resulting `soft glassy rheology' (SGR) ... More
Do current-density nonlinearities cut off the glass transition?Nov 10 2005Extended mode coupling theories for dense fluids predict that nonlinear current-density couplings cut off the singular `ideal glass transition', present in the standard mode coupling theory where such couplings are ignored. We suggest here that, rather ... More
Spontaneous symmetry breaking in active droplets provides a generic route to motilityNov 20 2012We explore a generic mechanism whereby a droplet of active matter acquires motility by the spontaneous breakdown of a discrete symmetry. The model we study offers a simple representation of a "cell extract" comprising, e.g., a droplet of actomyosin solution. ... More
Bijels Containing Magnetic Particles: A Simulation StudyJan 17 2011Bicontinuous, interfacially jammed emulsion gels (bijels) represent a class of soft solid materials in which interpenetrating domains of two immiscible fluids are stabilized by an interfacial colloidal monolayer. Such structures can be formed by arrested ... More
Osmotic Stabilisation of Concentrated Emulsions and FoamsJan 19 2001In the absence of coalescence, coarsening of emulsions (and foams) is controlled by molecular diffusion of dispersed phase between droplets/bubbles. Studies of dilute emulsions have shown how the osmotic pressure of a trapped species within droplets can ... More
Phase ordering of two-dimensional symmetric binary fluids: a droplet scaling stateJan 10 2001The late-stage phase ordering, in $d=2$ dimensions, of symmetric fluid mixtures violates dynamical scaling. We show however that, even at 50/50 volume fractions, if an asymmetric droplet morphology is initially present then this sustains itself, throughout ... More
Cytoplasmic streaming in plant cells: the role of wall slipFeb 29 2012We present a computer simulation study, via lattice Boltzmann simulations, of a microscopic model for cytoplasmic streaming in algal cells such as those of Chara corallina. We modelled myosin motors tracking along actin lanes as spheres undergoing directed ... More
Diffusive Evolution of Stable and Metastable Phases I: Local Dynamics of InterfacesJan 20 1997We find analytical solutions to the Cahn-Hilliard equation for the dynamics of an interface in a system with a conserved order parameter (Model B). We show that, although steady-state solutions of Model B are unphysical in the far-field, they shed light ... More
Stabilisation of Emulsions by Trapped SpeciesJan 13 1998Apr 28 1998We consider an emulsion whose droplets contain a trapped species (insoluble in the continuous phase), and study the emulsion's stability against coarsening via Lifshitz-Slyozov dynamics (Ostwald Ripening). Extending an earlier treatment by Kabalnov et ... More
Rheology of giant micellesFeb 02 2007Giant micelles are elongated, polymer-like objects created by the self-assembly of amphiphilic molecules (such as detergents) in solution. Giant micelles are typically flexible, and can become highly entangled even at modest concentrations. The resulting ... More
First-Principles Constitutive Equation for Suspension RheologyMay 09 2012We provide a detailed derivation of a recently developed first-principles approach to calculating averages in systems of interacting, spherical Brownian particles under time-dependent flow. Although we restrict ourselves to flows which are both homogeneous ... More
A First-Principles Constitutive Equation for Suspension RheologyAug 11 2008Using mode-coupling theory, we derive a constitutive equation for the nonlinear rheology of dense colloidal suspensions under arbitrary time-dependent homogeneous flow. Generalizing previous results for simple shear, this allows the full tensorial structure ... More
Steady-state hydrodynamic instabilities of active liquid crystals: Hybrid lattice Boltzmann simulationsAug 15 2007We report hybrid lattice Boltzmann (HLB) simulations of the hydrodynamics of an active nematic liquid crystal sandwiched between confining walls with various anchoring conditions. We confirm the existence of a transition between a passive phase and an ... More
Viscoelastic and elastomeric active matter: Linear instability and nonlinear dynamicsDec 14 2015Mar 29 2016We consider a continuum model of active viscoelastic matter, whereby an active nematic liquid-crystal is coupled to a minimal model of polymer dynamics with a viscoelastic relaxation time $\tau_C$. To explore the resulting interplay between active and ... More
Lattice Boltzmann simulations of spontaneous flow in active liquid crystals: the role of boundary conditionsJun 28 2007Active liquid crystals or active gels are soft materials which can be physically realised e.g. by preparing a solution of cytoskeletal filaments interacting with molecular motors. We study the hydrodynamics of an active liquid crystal in a slab-like geometry ... More
Dense colloidal suspensions under time-dependent shearSep 01 2006We consider the nonlinear rheology of dense colloidal suspensions under a time-dependent simple shear flow. Starting from the Smoluchowski equation for interacting Brownian particles advected by shearing (ignoring fluctuations in fluid velocity) we develop ... More
Nonlinear dynamics and rheology of active fluids: simulations in two dimensionsDec 15 2010We report simulations of a continuum model for (apolar, flow aligning) active fluids in two dimensions. Both free and anchored boundary conditions are considered, at parallel confining walls that are either static or moving at fixed relative velocity. ... More
Thermal fluctuations in the lattice Boltzmann method for non-ideal fluidsSep 01 2010Nov 29 2010We introduce thermal fluctuations in the lattice Boltzmann method for non-ideal fluids. A fluctuation-dissipation theorem is derived within the Langevin framework and applied to a specific lattice Boltzmann model that approximates the linearized fluctuating ... More
Arrest of Fluid Demixing by Nanoparticles: A Computer Simulation StudyApr 02 2008We use lattice Boltzmann simulations to investigate the formation of arrested structures upon demixing of a binary solvent containing neutrally wetting colloidal particles. Previous simulations for symmetric fluid quenches pointed to the formation of ... More
Competition between glass transition and liquid-gas separation in attracting colloidsOct 19 2006We present simulation results addressing the phenomena of colloidal gelation induced by attractive interactions. The liquid-gas transition is prevented by the glass arrest at high enough attraction strength, resulting in a colloidal gel. The dynamics ... More
A First-Principles Constitutive Equation for Suspension Rheology: Supplementary MaterialAug 11 2008Additional supplementary material for the paper `A First-Principles Constitutive Equation for Suspension Rheology'.
Schematic Mode Coupling Theory of Glass Rheology: Single and Double Step StrainsMar 28 2012Mode coupling theory (MCT) has had notable successes in addressing the rheology of hard-sphere colloidal glasses, and also soft colloidal glasses such as star-polymers. Here, we explore the properties of a recently developed MCT-based schematic constitutive ... More
Persistence exponents in a 3D symmetric binary fluid mixtureOct 21 1999The persistence exponent, theta, is defined by N_F sim t^theta, where t is the time since the start of the coarsening process and the "no-flip fraction", N_F, is the number of points that have not seen a change of "color" since t=0. Here we investigate ... More
A Simple Model for the Deformation-Induced Relaxation of Glassy PolymersOct 18 2011Glassy polymers show strain hardening: at constant extensional load, their flow first accelerates, then arrests. Recent experiments have found this to be accompanied by a striking and unexplained dip in the segmental relaxation time. Here we explain such ... More
Schematic mode coupling theories for shear thinning, shear thickening, and jammingOct 24 2003Mode coupling theory (MCT) appears to explain several, though not all, aspects of the glass transition in colloids (particularly when short-range attractions are present). Developments of MCT, from rational foundations in statistical mechanics, account ... More
Glass transitions and shear thickening suspension rheologyJun 18 2004We introduce a class of simple models for shear thickening and/ or `jamming' in colloidal suspensions. These are based on schematic mode coupling theory (MCT) of the glass transition, having a memory term that depends on a density variable, and on both ... More
A minimal physical model captures the shapes of crawling cellsFeb 25 2015Cell motility in higher organisms (eukaryotes) is crucial to biological functions ranging from wound healing to immune response, and also implicated in diseases such as cancer. For cells crawling on hard surfaces, significant insights into motility have ... More
Role of inertia in two-dimensional deformation and breakup of a dropletDec 20 2002We investigate by Lattice Boltzmann methods the effect of inertia on the deformation and break-up of a two-dimensional fluid droplet surrounded by fluid of equal viscosity (in a confined geometry) whose shear rate is increased very slowly. We give evidence ... More
Hard discs under steady shear: comparison of Brownian dynamics simulations and mode coupling theoryJan 19 2010Brownian dynamics simulations of bidisperse hard discs moving in two dimensions in a given steady and homogeneous shear flow are presented close to and above the glasstransition density. The stationary structure functions and stresses of shear-melted ... More
Topological effects in ring polymers (II): Influence of persistence lengthOct 27 1999The interplay of topological constraints and persistence length of ring polymers in their own melt is investigated by means of dynamical Monte Carlo simulations of a three dimensional lattice model. We ask if the results are consistent with an asymptotically ... More
Diffusion and rheology in a model of glassy materialsJan 25 1999We study self-diffusion within a simple hopping model for glassy materials. (The model is Bouchaud's model of glasses [J.-P. Bouchaud, J. Physique I 2, 1705 (1992)], as extended to describe rheological properties [P. Sollich, F. Lequeux, P. Hebraud and ... More
Topological effects in ring polymers: A computer simulation studyMay 20 1998Unconcatenated, unknotted polymer rings in the melt are subject to strong interactions with neighboring chains due to the presence of topological constraints. We study this by computer simulation using the bond-fluctuation algorithm for chains with up ... More
Stress Propagation and Arching in Static SandpilesJul 13 1996Sep 24 1996We present a new approach to the modelling of stress propagation in static granular media, focussing on the conical sandpile constructed from a point source. We view the medium as consisting of cohesionless hard particles held up by static frictional ... More
Binary fluid demixing: The crossover regionMar 13 2001By performing lattice Boltzmann simulations of a binary mixture, we scrutinize the dynamical scaling hypothesis for the spinodal decomposition of binary mixtures for the crossover region, i.e. the region of parameters in the growth curve where neither ... More
Age-dependent transient shear banding in soft glassesNov 18 2010We study numerically the formation of long-lived transient shear bands during shear startup within two models of soft glasses (a simple fluidity model and an adapted `soft glassy rheology' model). The degree and duration of banding depends strongly on ... More
Sensitivity of arrest in mode-coupling glasses to low-q structureDec 01 2005May 25 2006We quantify, within mode coupling theory, how changes in the liquid structure affect that of the glass. Apart from the known sensitivity to the structure factor $S(q)$ at wavevectors around the first sharp diffraction peak $q_0$, we find a strong (and ... More
Ageing and Rheology in Soft MaterialsJul 07 1999We study theoretically the role of ageing in the rheology of soft materials. We define several generalized rheological response functions suited to ageing samples (in which time translation invariance is lost). These are then used to study ageing effects ... More
Shear banding, aging and noise dynamics in soft glassy materialsDec 17 2008The `soft glassy rheology' (SGR) model gives an appealing account of the flow of nonergodic soft materials in terms of the local yield dynamics of mesoscopic elements. Newtonian, power-law, and yield-stress fluid regimes arise on varying a `noise temperature', ... More
Swelling and Dissolution of onion phases: The effect of temperatureSep 20 2000Contact experiments have been performed between an onion lamellar phase and brine, in the SDS/octanol/brine system. Using video microscopy we have studied the nonequilibrium behaviour of the swelling and dissolution process of onions. Experiments at T=20degC ... More
Kinetic pathways of multi-phase surfactant systemsSep 20 2000The relaxation following a temperature quench of two-phase (lamellar and sponge phase) and three-phase (lamellar, sponge and micellar phase) samples, has been studied in an SDS/octanol/brine system. In the three-phase case we have observed samples that ... More
Jamming transitions in a schematic model of suspension rheologyOct 15 2002Jun 09 2003We study the steady-state response to applied stress in a simple scalar model of sheared colloids. Our model is based on a schematic (F2) model of the glass transition, with a memory term that depends on both stress and shear rate. For suitable parameters, ... More
Dilatancy, Jamming, and the Physics of GranulationNov 23 2004Granulation is a process whereby a dense colloidal suspension is converted into pasty granules (surrounded by air) by application of shear. Central to the stability of the granules is the capillary force arising from the interfacial tension between solvent ... More
Langevin theory of fluctuations in the discrete Boltzmann equationDec 16 2010Mar 31 2011The discrete Boltzmann equation for both the ideal and a non-ideal fluid is extended by adding Langevin noise terms in order to incorporate the effects of thermal fluctuations. After casting the fluctuating discrete Boltzmann equation in a form appropriate ... More
Computational confirmation of scaling predictions for equilibrium polymersMay 20 1998We report the results of extensive Dynamic Monte Carlo simulations of systems of self-assembled Equilibrium Polymers without rings in good solvent. Confirming recent theoretical predictions, the mean-chain length is found to scale as $\Lav = \Lstar (\phi/\phistar)^\alpha ... More
Run-and-tumble particles with hydrodynamics: sedimentation, trapping and upstream swimmingMar 09 2010Jun 30 2010We simulate by lattice Boltzmann the nonequilibrium steady states of run-and-tumble particles (inspired by a minimal model of bacteria), interacting by far-field hydrodynamics, subject to confinement. Under gravity, hydrodynamic interactions barely perturb ... More
Facilitated diffusion on mobile DNA: configurational traps and sequence heterogeneityDec 07 2012We present Brownian dynamics simulations of the facilitated diffusion of a protein, modelled as a sphere with a binding site on its surface, along DNA, modelled as a semi-flexible polymer. We consider both the effect of DNA organisation in 3D, and of ... More
Colloids in liquid crystals: a lattice Boltzmann studyFeb 10 2011We propose a hybrid lattice Boltzmann algorithm to simulate the hydrodynamics of colloidal particles inside a liquid crystalline host. To validate our algorithm, we study the static and the microrheology of a colloid in a nematic, with tangential anchoring ... More
Thermodynamics of Blue Phases In Electric FieldsMar 04 2010We present extensive numerical studies to determine the phase diagrams of cubic and hexagonal blue phases in an electric field. We confirm the earlier prediction that hexagonal phases, both 2 and 3 dimensional, are stabilized by a field, but we significantly ... More
A cluster mode-coupling approach to weak gelation in attractive colloidsOct 23 2003Apr 05 2004Mode-coupling theory (MCT) predicts arrest of colloids in terms of their volume fraction, and the range and depth of the interparticle attraction. We discuss how effective values of these parameters evolve under cluster aggregation. We argue that weak ... More
Colloids in Cholesterics: Size-Dependent Defects and Non-Stokesian MicrorheologyJan 07 2011We simulate a colloidal particle (radius R) in a cholesteric liquid crystal (pitch p) with tangential order parameter alignment at the particle surface. The local defect structure evolves from a dipolar pair of surface defects (boojums) at small R/p to ... More
Lattice Boltzmann simulations of liquid crystalline fluids: active gels and blue phasesSep 06 2010Lattice Boltzmann simulations have become a method of choice to solve the hydrodynamic equations of motion of a number of complex fluids. Here we review some recent applications of lattice Boltzmann to study the hydrodynamics of liquid crystalline materials. ... More
Development of Stresses in Cohesionless Poured SandMar 21 1998The pressure distribution beneath a conical sandpile, created by pouring sand from a point source onto a rough rigid support, shows a pronounced minimum below the apex (`the dip'). Recent work of the authors has attempted to explain this phenomenon by ... More
Rheological Chaos in a Scalar Shear-Thickening ModelApr 07 2002Jul 08 2002We study a simple scalar constitutive equation for a shear-thickening material at zero Reynolds number, in which the shear stress \sigma is driven at a constant shear rate \dot\gamma and relaxes by two parallel decay processes: a nonlinear decay at a ... More
Dynamical Monte Carlo Study of Equilibrium Polymers : Static PropertiesMay 20 1998We report results of extensive Dynamical Monte Carlo investigations on self-assembled Equilibrium Polymers (EP) without loops in good solvent. (This is thought to provide a good model of giant surfactant micelles.) Using a novel algorithm we are able ... More
Simulation study of Non-ergodicity Transitions: Gelation in Colloidal Systems with Short Range AttractionsNov 05 2002Computer simulations were used to study the gel transition occurring in colloidal systems with short range attractions. A colloid-polymer mixture was modelled and the results were compared with mode coupling theory expectations and with the results for ... More
Comparative simulation study of colloidal gels and glassesSep 20 2001Using computer simulations, we identify the mechanisms causing aggregation and structural arrest of colloidal suspensions interacting with a short-ranged attraction at moderate and high densities. Two different non-ergodicity transitions are observed. ... More
Active Field TheoriesApr 02 2019Lecture Notes for Les Houches 2018 Summer School on Active Matter and Nonequilibrium Statistical Physics. These notes give an introduction to statistical field theories of active matter. After showing an example of how such theories can be created bottom-up ... More
Light-induced self-assembly of active rectification devicesJul 07 2015Apr 05 2016Self-propelled colloidal objects, such as motile bacteria or synthetic microswimmers, have microscopically irreversible individual dynamics - a feature they share with all living systems. The incoherent behaviour of individual swimmers can then be harnessed ... More
Intracellular facilitated diffusion: searchers, crowders and blockersSep 04 2013In bacteria, regulatory proteins search for a specific DNA binding target via "facilitated diffusion": a series of rounds of 3D diffusion in the cytoplasm, and 1D linear diffusion along the DNA contour. Using large scale Brownian dynamics simulations ... More
Ordering dynamics of blue phases entails kinetic stabilization of amorphous networksJun 22 2010Aug 23 2010The cubic blue phases of liquid crystals are fascinating and technologically promising examples of hierarchically structured soft materials, comprising ordered networks of defect lines (disclinations) within a liquid crystalline matrix. We present the ... More
Domain growth in cholesteric blue phases: hybrid lattice Boltzmann simulationsJan 21 2009Here we review a hybrid lattice Boltzmann algorithm to solve the equations of motion of cholesteric liquid crystals. The method consists in coupling a lattice Boltzmann solver for the Navier-Stokes equation to a finite difference method to solve the dynamical ... More
Self-Assembly and Nonlinear Dynamics of Dimeric Colloidal Rotors in CholestericsJan 04 2012We study by simulation the physics of two colloidal particles in a cholesteric liquid crystal with tangential order parameter alignment at the particle surface. The effective force between the pair is attractive at short range and favors assembly of colloid ... More
On the structure of blue phase IIIOct 31 2011We report large scale simulations of the blue phases of cholesteric liquid crystals. Our results suggest a structure for blue phase III, the blue fog, which has been the subject of a long debate in liquid crystal physics. We propose that blue phase III ... More
Jamming, Force Chains and Fragile MatterMar 16 1998We consider materials whose mechanical integrity is the result of a jamming process. We argue that such media are generically "fragile": unable to support certain types of incremental loading without plastic rearrangement. Fragility is linked to the marginal ... More
Jamming, hysteresis and oscillation in scalar models for shear thickeningSep 02 2001Oct 10 2001We investigate shear thickening and jamming within the framework of a family of spatially homogeneous, scalar rheological models. These are based on the `soft glassy rheology' model of Sollich et al. [Phys. Rev. Lett. 78, 2020 (1997)], but with an effective ... More
Equilibrium Onions?Jul 01 2004We demonstrate the possibility of a stable equilibrium multi-lamellar (``onion'') phase in pure lamellar systems (no excess solvent) due to a sufficiently negative Gaussian curvature modulus. The onion phase is stabilized by non-linear elastic moduli ... More
Aging in attraction-driven colloidal glassesMar 24 2006Oct 19 2006Aging in an attraction-driven colloidal glass is studied by computer simulations. The system is equilibrated without attraction and instantaneously ``quenched'', at constant colloid volume fraction, to one of two states beyond the glass transition; one ... More
Dynamical heterogeneities in an attraction driven colloidal glassOct 17 2005Jan 16 2006The dynamical heterogeneities (DH) in non-ergodic states of an attractive colloidal glass are studied, as a function of the waiting time. Whereas the fluid states close to vitrify showed strong DH, the distribution of squared displacements of the glassy ... More
Tests of Dynamical Scaling in 3-D Spinodal DecompositionOct 22 1998We simulate late-stage coarsening of a 3-D symmetric binary fluid. With reduced units l,t (with scales set by viscosity, density and surface tension) our data extends two decades in t beyond earlier work. Across at least four decades, our own and others' ... More
Delayed solidification of soft glasses: New experiments, and a theoretical challengeApr 27 2012When subjected to large amplitude oscillatory shear stress, aqueous Laponite suspensions show an abrupt solidification transition after a long delay time tc. We measure the dependence of tc on stress amplitude, frequency, and on the age-dependent initial ... More
Rheological instability in a simple shear thickening modelAug 14 2001Oct 10 2001We study the strain response to steady imposed stress in a spatially homogeneous, scalar model for shear thickening, in which the local rate of yielding \Gamma(l) of mesoscopic `elastic elements' is not monotonic in the local strain l. Despite this, the ... More
Phase Separation in Binary Fluid Mixtures with Continuously Ramped TemperatureApr 03 2003We consider the demixing of a binary fluid mixture, under gravity, which is steadily driven into a two phase region by slowly ramping the temperature. We assume, as a first approximation, that the system remains spatially isothermal, and examine the interplay ... More
Fluctuating lattice BoltzmannFeb 24 2004May 31 2005The lattice Boltzmann algorithm efficiently simulates the Navier Stokes equation of isothermal fluid flow, but ignores thermal fluctuations of the fluid, important in mesoscopic flows. We show how to adapt the algorithm to include noise, satisfying a ... More
Arrested phase separation in reproducing bacteria: a generic route to pattern formation?Jan 04 2010We present a generic mechanism by which reproducing microorganisms, with a diffusivity that depends on the local population density, can form stable patterns. It is known that a decrease of swimming speed with density can promote separation into bulk ... More
Local size segregation in polydisperse hard sphere fluidsSep 23 1999The structure of polydisperse hard sphere fluids, in the presence of a wall, is studied by the Rosenfeld density functional theory. Within this approach, the local excess free energy depends on only four combinations of the full set of density fields. ... More
Mode Coupling and Dynamical Heterogeneity in Colloidal Gelation: A Simulation StudySep 29 2004We present simulation results addressing the dynamics of a colloidal system with attractive interactions close to gelation. Our interaction also has a soft, long range repulsive barrier which suppresses liquid-gas type phase separation at long wavelengths. ... More
Dynamical heterogeneities close to a colloidal gelDec 14 2004Dynamical heterogeneities in a colloidal fluid close to gelation are studied by means of computer simulations. A clear distinction between some fast particles and the rest, slow ones, is observed, yielding a picture of the gel composed by two populations ... More
Hard Spheres: Crystallization and Glass FormationAug 12 2009Motivated by old experiments on colloidal suspensions, we report molecular dynamics simulations of assemblies of hard spheres, addressing crystallization and glass formation. The simulations cover wide ranges of polydispersity s (standard deviation of ... More
Thermodynamic Interpretation of Soft Glassy Rheology ModelsJan 16 2012Mesoscopic models play an important role in our understanding of the deformation and flow of amorphous materials. One such description, based on the Shear Transformation Zone (STZ) theory, has recently been re-formulated within a non-equilibrium thermodynamics ... More
Non--Newtonian viscosity of interacting Brownian particles: comparison of theory and dataOct 09 2002A recent first-principles approach to the non-linear rheology of dense colloidal suspensions is evaluated and compared to simulation results of sheared systems close to their glass transitions. The predicted scenario of a universal transition of the structural ... More
Does a growing static length scale control the glass transition?May 18 2017Sep 28 2017Several theories of the glass transition propose that the structural relaxation time {\tau}{\alpha} is controlled by a growing static length scale {\xi} that is determined by the free energy landscape but not by the local dynamical rules governing its ... More
Shearing active gels close to the isotropic-nematic transitionMay 13 2008We study numerically the rheological properties of a slab of active gel close o the isotropic-nematic transition. The flow behavior shows strong dependence on sample size, boundary conditions, and on the bulk constitutive curve, which, on entering the ... More
Projected free energies for polydisperse phase equilibriaNov 28 1997A `polydisperse' system has an infinite number of conserved densities. We give a rational procedure for projecting its infinite-dimensional free energy surface onto a subspace comprising a finite number of linear combinations of densities (`moments'), ... More
A mode coupling theory for Brownian particles in homogeneous steady shear flowMar 25 2009A microscopic approach is presented for calculating general properties of interacting Brownian particles under steady shearing. We start from exact expressions for shear-dependent steady-state averages, such as correlation and structure functions, in ... More
Crystallization of hard-sphere glassesOct 20 2009We study by molecular dynamics the interplay between arrest and crystallization in hard spheres. For state points in the plane of volume fraction ($0.54 \leq phi \leq 0.63$) and polydispersity ($0 \leq s \leq 0.085$), we delineate states that spontaneously ... More
Theory and simulation of gelation, arrest and yielding in attracting colloidsMar 29 2004We present some recent theory and simulation results addressing the phenomena of colloidal gelation at both high and low volume fractions, in the presence of short-range attractive interactions. We discuss the ability of mode-coupling theory and its adaptations ... More
Hawkes process as a model of social interactions: a view on video dynamicsJul 22 2009Jan 05 2010We study by computer simulation the "Hawkes process" that was proposed in a recent paper by Crane and Sornette (Proc. Nat. Acad. Sci. USA 105, 15649 (2008)) as a plausible model for the dynamics of YouTube video viewing numbers. We test the claims made ... More
Integration through transients for Brownian particles under steady shearJan 24 2005Mar 15 2005Starting from the microscopic Smoluchowski equation for interacting Brownian particles under stationary shearing, exact expressions for shear-dependent steady-state averages, correlation and structure functions, and susceptibilities are obtained, which ... More
Schematic models for dynamic yielding of sheared colloidal glassesJul 22 2002Sep 04 2002The nonlinear rheological properties of dense suspensions are discussed within simplified models, suggested by a recent first principles approach to the model of Brownian particles in a constant-velocity-gradient solvent flow. Shear thinning of colloidal ... More
Theory of nonlinear rheology and yielding of dense colloidal suspensionsApr 30 2002Oct 22 2002A first principles approach to the nonlinear flow of dense suspensions is presented which captures shear thinning of colloidal fluids and dynamical yielding of colloidal glasses. The advection of density fluctuations plays a central role, suppressing ... More
Motility-Induced Phase SeparationJun 13 2014Self-propelled particles include both self-phoretic synthetic colloids and various micro-organisms. By continually consuming energy, they bypass the laws of equilibrium thermodynamics. These laws enforce the Boltzmann distribution in thermal equilibrium: ... More
Inertia, coarsening and fluid motion in binary mixturesJul 31 1999Symmetric binary fluids, quenched into a regime of immiscibility, undergo phase separation by spinodal decomposition. In the late stages, the fluids are separated by sharply defined, but curved, interfaces: the resulting Laplace pressure drives fluid ... More
Modeling the Relaxation of Polymer Glasses under Shear and Elongational LoadsSep 05 2012Glassy polymers show strain hardening: at constant extensional load, their flow first accelerates, then arrests. Recent experiments under such loading have found this to be accompanied by a striking dip in the segmental relaxation time. This can be explained ... More