The Experts below are selected from a list of 41856 Experts worldwide ranked by ideXlab platform
Per Arne Rikvold - One of the best experts on this subject based on the ideXlab platform.
-
complete catalog of ground state diagrams for the general three state Lattice Gas model with nearest neighbor interactions on a square Lattice
arXiv: Statistical Mechanics, 2019Co-Authors: Daniel Silva, Per Arne RikvoldAbstract:The ground states of the general three-state Lattice-Gas (equivalently, $S=1$ Ising) model with nearest-neighbor interactions on a square Lattice are explored in the full, five-dimensional parameter space of three interaction constants and two generalized chemical potentials or fields. The resulting, complete catalog of fifteen topologically different ground-state diagrams (zero-temperature phase diagrams) is discussed in both Lattice-Gas and Ising-spin language. The results extend those of a recent study in a reduced parameter space [V. F. Fefelov, et al., Phys. Chem. Chem. Phys., 2018, 20, 10359--10368], which identified six different ground-state diagrams.
-
complete catalog of ground state diagrams for the general three state Lattice Gas model with nearest neighbor interactions on a square Lattice
Physical Chemistry Chemical Physics, 2019Co-Authors: Daniel Silva, Per Arne RikvoldAbstract:The ground states of the general three-state Lattice-Gas (equivalently, S = 1 Ising) model with nearest-neighbor interactions on a square Lattice are explored in the full, five-dimensional parameter space of three interaction constants and two generalized chemical potentials or fields. The complete catalog of fifteen topologically different ground-state diagrams (zero-temperature phase diagrams), which show the regions of stability of the different ground states in the full parameter space of the model, is obtained and discussed in both Lattice-Gas and Ising-spin language. The results extend those of a recent study in a reduced parameter space [V. F. Fefelov, et al., Phys. Chem. Chem. Phys., 2018, 20, 10359–10368], which identified six topologically different ground-state diagrams.
-
effects of lateral diffusion on morphology and dynamics of a microscopic Lattice Gas model of pulsed electrodeposition
Journal of Chemical Physics, 2005Co-Authors: Stefan Frank, Daniel E Roberts, Per Arne RikvoldAbstract:The influence of nearest-neighbor diffusion on the decay of a metastable low-coverage phase (monolayer adsorption) in a square Lattice-Gas model of electrochemical metal deposition is investigated by kinetic Monte Carlo simulations. The phase-transformation dynamics are compared to the well-established Kolmogorov–Johnson–Mehl–Avrami theory. The phase transformation is accelerated by diffusion, but remains in accord with the theory for continuous nucleation up to moderate diffusion rates. At very high diffusion rates the phase-transformation kinetic shows a crossover to instantaneous nucleation. Then, the probability of medium-sized clusters is reduced in favor of large clusters. Upon reversal of the supersaturation, the adsorbate desorbs, but large clusters still tend to grow during the initial stages of desorption. Calculation of the free energy of subcritical clusters by enumeration of Lattice animals yields a quasiequilibrium distribution which is in reasonable agreement with the simulation results. Th...
-
effects of lateral diffusion on morphology and dynamics of a microscopic Lattice Gas model of pulsed electrodeposition
arXiv: Materials Science, 2004Co-Authors: Stefan Frank, Daniel E Roberts, Per Arne RikvoldAbstract:The influence of nearest-neighbor diffusion on the decay of a metastable low-coverage phase (monolayer adsorption) in a square Lattice-Gas model of electrochemical metal deposition is investigated by kinetic Monte Carlo simulations. The phase-transformation dynamics are compared to the well-established Kolmogorov-Johnson-Mehl-Avrami theory. The phase transformation is accelerated by diffusion, but remains in accord with the theory for continuous nucleation up to moderate diffusion rates. At very high diffusion rates the phase-transformation kinetic shows a crossover to instantaneous nucleation. Then, the probability of medium-sized clusters is reduced in favor of large clusters. Upon reversal of the supersaturation, the adsorbate desorbs, but large clusters still tend to grow during the initial stages of desorption. Calculation of the free energy of subcritical clusters by enumeration of Lattice animals yields a quasi-equilibrium distribution which is in reasonable agreement with the simulation results. This is an improvement relative to classical droplet theory, which fails to describe the distributions, since the macroscopic surface tension is a bad approximation for small clusters.
Alexander J Wagner - One of the best experts on this subject based on the ideXlab platform.
-
integer Lattice Gas with monte carlo collision operator recovers the Lattice boltzmann method with poisson distributed fluctuations
Physical Review E, 2018Co-Authors: Thomas Blommel, Alexander J WagnerAbstract:We examine a new kind of Lattice Gas that closely resembles modern Lattice Boltzmann methods. This new kind of Lattice Gas, which we call a Monte Carlo Lattice Gas, has interesting properties that shed light on the origin of the multirelaxation time collision operator, and it derives the equilibrium distribution for an entropic Lattice Boltzmann. Furthermore these Lattice Gas methods have Galilean invariant fluctuations given by a Poisson statistics, giving further insight into the properties that we should expect for fluctuating Lattice Boltzmann methods.
-
Lattice Gas with molecular dynamics collision operator
Physical Review E, 2017Co-Authors: Reza M Parsa, Alexander J WagnerAbstract:We introduce a Lattice Gas implementation that is based on coarse-graining a molecular dynamics (MD) simulation. Such a Lattice Gas is similar to standard Lattice Gases, but its collision operator is informed by an underlying MD simulation. This can be considered an optimal Lattice Gas implementation because it allows for the representation of any system that can be simulated with MD. We show here that equilibrium behavior of the popular Lattice Boltzmann algorithm is consistent with this optimal Lattice Gas. This comparison allows us to make a more accurate identification of the expressions for temperature and pressure in Lattice Boltzmann simulations, which turn out to be related not only to the physical temperature and pressure but also to the Lattice discretization. We show that for any spatial discretization, we need to choose a particular temporal discretization to recover the Lattice Boltzmann equilibrium.
Stephane Zaleski - One of the best experts on this subject based on the ideXlab platform.
-
Lattice Gas cellular automata simple models of complex hydrodynamics
1997Co-Authors: Daniel H Rothman, Stephane ZaleskiAbstract:Preface Acknowledgements 1. A simple model of fluid mechanics 2. Two routes to hydrodynamics 3. Inviscid two-dimensional Lattice-Gas hydrodynamics 4. Viscous two-dimensional hydrodynamics 5. Some simple 3D models 6. The Lattice-Boltzmann method 7. Using the Boltzmann method 8. Miscible fluids 9. Immiscible Lattice Gases 10. Lattice-Boltzmann method for immiscible fluids 11. Immiscible Lattice Gases in three dimensions 12. Liquid-Gas models 13. Flow through porous media 14. Equilibrium statistical mechanics 15. Hydrodynamics in the Boltzmann approximation 16. Phase separation 17. Interfaces 18. Complex fluids and patterns Appendices Author Index Subject Index.
-
Lattice Gas models of phase separation interfaces phase transitions and multiphase flow
Reviews of Modern Physics, 1994Co-Authors: Daniel H Rothman, Stephane ZaleskiAbstract:Momentum-conserving Lattice Gases are simple, discrete, microscopic models of fluids. This review describes their hydrodynamics, with particular attention given to the derivation of macroscopic constitutive equations from microscopic dynamics. Lattice-Gas models of phase separation receive special emphasis. The current understanding of phase transitions in these momentum-conserving models is reviewed; included in this discussion is a summary of the dynamical properties of interfaces. Because the phase-separation models are microscopically time irreversible, interesting questions are raised about their relationship to real fluid mixtures. Simulation of certain complex-fluid problems, such as multiphase flow through porous media and the interaction of phase transitions with hydrodynamics, is illustrated.
-
modeling water infiltration in unsaturated porous media by interacting Lattice Gas cellular automata
Water Resources Research, 1994Co-Authors: L B Di Pietro, A Melayah, Stephane ZaleskiAbstract:A two-dimensional Lattice Gas-cellular automaton fluid model with long-range interactions (Appert and Zaleski, 1990) is used to simulate saturated and unsaturated water infiltration in porous media. Water and Gas within the porous medium are simulated by applying the dense and the light phase, respectively, of the cellular automaton fluid. Various wetting properties can be modeled when adjusting the corresponding solid-liquid interactions. The Lattice Gas rules include a gravity force step to allow buoyancy-driven flow. The model handles with ease complex geometries of the solid, and an algorithm for generating random porous media is presented. The results of four types of simulation experiments are presented: (1) We verified Poiseuille's law for steady and saturated flow between two parallel plates. (2) We analyzed transient water infiltration between two parallel plates of varying degrees of saturation and various apertures. (3) Philip's infiltration equation was adequately simulated in an unsaturated porous medium. (4) Infiltration into an aggregated medium containing one vertical parallel crack was simulated. Further applications of this Lattice Gas method for studying unsaturated flow in porous media are discussed.
Tomášik Miroslav - One of the best experts on this subject based on the ideXlab platform.
-
Simulace dvojrozměrného toku kolem překážek za použití "Lattice-Gas" celulárních automatů
2017Co-Authors: Tomášik MiroslavAbstract:Cellular automata constitues original computational methods, that found its application in many disciplines. The special class of cellular automata, so called Lattice Gas automata were succesfull in dealing with many challenges in hydrodynamic simulations, and they bootstrap one of the most perspective CFD methods, the Lattice Boltzmann models. In the theoretical part, we follow the evolution of the Lattice Gas automata, explore the theory behind them, and from their microdynamics, we derive the macroscopic equations. In the practical part, we implemented two distincet types of LGCA, the pair-interaction automata and FCHC. We applied them on the flow around obstacles of various shapes. The scientifically most relevant part concerns statistical properties of the turbulent flow simmulated by LGCA, but requires further research to conclude it. Powered by TCPDF (www.tcpdf.org
-
Simulace dvojrozměrného toku kolem překážek za použití "Lattice-Gas" celulárních automatů
Univerzita Karlova Matematicko-fyzikální fakulta, 2017Co-Authors: Tomášik MiroslavAbstract:Celulární automaty představují originální výpočetní metodu, která našla uplatnění v mnohých oblastech, a pole její působnosti se stále zvěčšuje. Speciální třída celulárních automatů, Lattice-Gas celulární automaty (LGCA) se s úspěchem utkala z mnohýma problémama v oblasti simulaci toku tekutin, a vyvynula se v jednu z nejperspektívnějších CFD metod, v Lattice-Boltzmanovu metodu. V teoretické části se zabíváme vývojem LGCA, vysvěltíme jejich teoretické základy a z jejich mikrodynamického popisu odvodíme hydrodynamické rovnice. V praktické části implementujeme dva význačné typy LGCA, Pair-interaction automat, a FCHC. Aplikujeme je na 3D tok kolem překážek nejrúznějších tvarú. Vědecky nejzajímavější část je věnovaná statistickým vlastnostem turbulentního toku, simulovaného těmito automaty, avšak bude zapotřeby delší výskum abychom mohli interpretovat získané výsledky. Powered by TCPDF (www.tcpdf.org)Cellular automata constitues original computational methods, that found its application in many disciplines. The special class of cellular automata, so called Lattice Gas automata were succesfull in dealing with many challenges in hydrodynamic simulations, and they bootstrap one of the most perspective CFD methods, the Lattice Boltzmann models. In the theoretical part, we follow the evolution of the Lattice Gas automata, explore the theory behind them, and from their microdynamics, we derive the macroscopic equations. In the practical part, we implemented two distincet types of LGCA, the pair-interaction automata and FCHC. We applied them on the flow around obstacles of various shapes. The scientifically most relevant part concerns statistical properties of the turbulent flow simmulated by LGCA, but requires further research to conclude it. Powered by TCPDF (www.tcpdf.org)Institute of Theoretical PhysicsÚstav teoretické fyzikyMatematicko-fyzikální fakultaFaculty of Mathematics and Physic
James W Evans - One of the best experts on this subject based on the ideXlab platform.
-
atomistic Lattice Gas modeling of co oxidation on pd 100 temperature programed spectroscopy and steady state behavior
Journal of Chemical Physics, 2006Co-Authors: Dajiang Liu, James W EvansAbstract:We have developed an atomistic Lattice-Gas model for the catalytic oxidation of CO on single-crystal Pd(100) surfaces under ultrahigh vacuum conditions. This model necessarily incorporates an detailed description of adlayer ordering and adsorption-desorption kinetics both for CO on Pd(100), and for oxygen on Pd(100). Relevant energetic parameters are determined by comparing model predictions with experiment, together with some guidance from density functional theory calculations. The latter also facilitates description of the interaction and reaction of adsorbed CO and oxygen. Kinetic Monte Carlo simulations of this reaction model are performed to predict temperature-programed reaction spectra, as well as steady-state bifurcation behavior.
-
from atomistic Lattice Gas models for surface reactions to hydrodynamic reaction diffusion equations
Chaos, 2002Co-Authors: James W Evans, Michael Joseph TammaroAbstract:Atomistic Lattice-Gas models for surface reactions can accurately describe spatial correlations and ordering in chemisorbed layers due to adspecies interactions or due to limited mobility of some adspecies. The primary challenge in such modeling is to describe spatiotemporal behavior in the physically relevant “hydrodynamic” regime of rapid diffusion of (at least some) reactant adspecies. For such models, we discuss the development of exact reaction-diffusion equations (RDEs) describing mesoscale spatial pattern formation in surface reactions. Formulation and implementation of these RDEs requires detailed analysis of chemical diffusion in mixed reactant adlayers, as well as development of novel hybrid and parallel simulation techniques.
