scholarly journals A thermalized electrokinetics model including stochastic reactions suitable for multiscale simulations of reaction-advection-diffusion systems

2021 ◽  
Author(s):  
Ingo Tischler ◽  
Florian Weik ◽  
Robert Kaufmann ◽  
Michael Kuron ◽  
Rudolf Weeber ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Code Generation ◽  
Lattice Boltzmann ◽  
Soft Matter ◽  
Thermal Fluctuations ◽  
Reaction Model ◽  
Diffusion Reaction ◽  
Coarse Grained ◽  
Ion Distribution ◽  
Carrier Fluid

We introduce a scheme to simulate the spatial and temporal evolution of the densities of charged species, taking into account diffusion, thermal fluctuations, coupling to a carrier fluid, and chemical reactions. To this end, the diffusive fluxes in the electrokinetic model by Capuani et al. [1] are supplemented with thermal fluctuations. Chemical reactions are included via an additional source term in the mass balance equation. The diffusion-reaction model is then coupled to a solver for fluctuating hydrodynamics based on the lattice Boltzmann method. This combination is particularly useful for soft matter simulations, due to the ability to couple particles to the lattice-Boltzmann fluid. These could, e.g., be charged colloids or polymers, which then interact with an ion distribution. We describe one implementations based on the automatic code generation tools pystencils and lbmpy, and another one that is contained in the molecular dynamics package ESPResSo and that allows for an easy coupling of particles to the density fields. We validate our implementations by comparing to several known analytic results. Our method can be applied to coarse-grained catalysis problems as well as to many other multi-scale problems that require the coupling of explicit-particle simulations to flow fields, diffusion, and reaction problems in arbitrary geometries.

scholarly journals A thermalized electrokinetics model including stochastic reactions suitable for multiscale simulations of reaction-advection-diffusion systems

2021 ◽  
Author(s):  
Ingo Tischler ◽  
Florian Weik ◽  
Robert Kaufmann ◽  
Michael Kuron ◽  
Rudolf Weeber ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Code Generation ◽  
Thermal Fluctuations ◽  
Reaction Model ◽  
Density Fluctuations ◽  
Diffusion Reaction ◽  
Coarse Grained ◽  
Carrier Fluid ◽  
Diffusive Fluxes ◽  
Automatic Code

We introduce a scheme to simulate the spatial and temporal evolution of the densities of charged species, taking into account diffusion, thermal fluctuations, coupling to a carrier fluid, and chemical reactions. To this end, the diffusive fluxes in the electrokinetic model by Capuani et al. [1] are supplemented with thermal fluctuations. Chemical reactions are included via an additional source term in the mass balance equation. The diffusion-reaction model is then coupled to a solver for fluctuating hydrodynamics based on the lattice Boltzmann method. We describe our implementations, one based on the automatic code generation tools using pystencils and lbmpy, and another one contained as in the molecular dynamics package ESPResSo which allows the coupling of particles to the density fields. We validate our implementations by demonstrating that the expected influence of density fluctuations on the reaction rate for chemical reactions of order > 1 is reproduced. Our novel algorithm will be applicable to coarse-grained catalysis problems as well as to many other multi-scale problems that require the coupling of explicit-particle simulations with flow fields, diffusion, and reaction problems in arbitrary geometries.

Coupling between Mass Transfer and Chemical Reactions during the Absorption of CO2 in a NaHCO3-Na2CO3 Brine : Experimental and Theoretical Study

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Christophe E Wylock ◽  
Pierre Colinet ◽  
Thierry Cartage ◽  
Benoît Haut
Keyword(s):  
Mass Transfer ◽  
Liquid Phase ◽  
Chemical Reactions ◽  
Reaction Model ◽  
Gas Absorption ◽  
Diffusion Reaction ◽  
Co2 Absorption ◽  
Bubble Liquid ◽  
Liquid Mass ◽  
Liquid Mass Transfer

This work deals with the study of the gas-liquid mass transfer, coupled with chemical reactions. The case of carbonic gas absorption in a brine of sodium carbonate and bicarbonate is investigated. It is performed in collaboration with Solvay SA. The aim of this work is to get a better understanding of this phenomenon. It would permit an optimization of the refined sodium bicarbonate production process. The basis of developed mathematical models is presented. The CO2 absorption is coupled with several chemical reactions taking place in the liquid phase. A mathematical modelling of this coupling is first developed. The equations of the model are solved numerically, using COMSOL Multiphysics. To model the bubble-liquid mass transfer of CO2, this diffusion-reaction model is completed by a representation of the liquid phase flow around the bubble. In order to validate experimentally each scale of modelling, two experimental devices are proposed.

scholarly journals Lattice Boltzmann simulations capture the multiscale physics of soft flowing crystals

2020 ◽  
Vol 378 (2175) ◽  
pp. 20190406
Author(s):  
A. Montessori ◽  
A. Tiribocchi ◽  
F. Bonaccorso ◽  
M. Lauricella ◽  
S. Succi
Keyword(s):  
Flow Rate ◽  
Lattice Boltzmann ◽  
Soft Matter ◽  
Complex Structure ◽  
Applied Pressure ◽  
Computational Cost ◽  
Computational Modelling ◽  
Coarse Grained ◽  
Full Detail ◽  
Formidable Challenge

The study of the underlying physics of soft flowing materials depends heavily on numerical simulations, due to the complex structure of the governing equations reflecting the competition of concurrent mechanisms acting at widely disparate scales in space and time. A full-scale computational modelling remains a formidable challenge since it amounts to simultaneously handling six or more spatial decades in space and twice as many in time. Coarse-grained methods often provide a viable strategy to significantly mitigate this issue, through the implementation of mesoscale supramolecular forces designed to capture the essential physics at a fraction of the computational cost of a full-detail description. Here, we review some recent advances in the design of a lattice Boltzmann mesoscale approach for soft flowing materials, inclusive of near-contact interactions (NCIs) between dynamic interfaces, as they occur in high packing-fraction soft flowing crystals. The method proves capable of capturing several aspects of the rheology of soft flowing crystals, namely, (i) a 3/2 power-law dependence of the dispersed phase flow rate on the applied pressure gradient, (ii) the structural transition between an ex-two and ex-one (bamboo) configurations with the associated drop of the flow rate, (iii) the onset of interfacial waves once NCI is sufficiently intense. This article is part of the theme issue ‘Fluid dynamics, soft matter and complex systems: recent results and new methods’.

Introduction to molecular simulations in soft matter

2017 ◽  
Author(s):  
J.-L. Barrat ◽  
J. J. de Pablo
Keyword(s):  
Phase Space ◽  
Numerical Methods ◽  
Theoretical Basis ◽  
Soft Matter ◽  
Relevant Literature ◽  
Coarse Grained ◽  
Soft Interfaces ◽  
Molecular Scale ◽  
Soft Matter Physics ◽  
The Continuum

We describe the main features of the coarse-grained models that are typically useful in modelling soft interfaces, from force fields to the continuum descriptions involving density fields. We explain the theoretical basis of the main numerical methods that are used to explore the phase space associated with these models. Finally, three recent examples, illustrating the spirit in which relatively simple simulations can contribute to solving pending problems in soft matter physics, are briefly described. Clearly, a short series of lectures can offer, at best, a biased and restricted view of the available approaches. Our aim here will be to provide the reader with such an overview, with a focus on methods and descriptions that ‘bridge the scale’ between the molecular scale and the continuum or quasi-continuum one. The objective to present a guide to the relevant literature—which has now to a large extent appeared in the form of textbooks.

The Fluctuating Lattice Boltzmann

2018 ◽  
Author(s):  
Sauro Succi
Keyword(s):  
Brownian Motion ◽  
Fluid Flow ◽  
Lattice Boltzmann ◽  
Thermal Fluctuations ◽  
Directed Motion ◽  
Statistical Fluctuations ◽  
Lattice Boltzmann Models ◽  
Motion Versus ◽  
The Way

Fluid flow at nanoscopic scales is characterized by the dominance of thermal fluctuations (Brownian motion) versus directed motion. Thus, at variance with Lattice Boltzmann models for macroscopic flows, where statistical fluctuations had to be eliminated as a major cause of inefficiency, at the nanoscale they have to be summoned back. This Chapter illustrates the “nemesis of the fluctuations” and describe the way they have been inserted back within the LB formalism. The result is one of the most active sectors of current Lattice Boltzmann research.

LBE for Generalized Hydrodynamics

2018 ◽  
Author(s):  
Sauro Succi
Keyword(s):  
Potential Energy ◽  
Electric Fields ◽  
Chemical Reactions ◽  
Soft Matter ◽  
Fluid Motion ◽  
Life Sciences ◽  
Scientific Discipline ◽  
The Past ◽  
Generalized Hydrodynamics ◽  
Internal Forces

This chapter presents the main techniques to incorporate the effects of external and/or internal forces within the LB formalism. This is a very important task, for it permits us to access a wide body of generalized hydrodynamic applications whereby fluid motion couples to a variety of additional physical aspects, such as gravitational and electric fields, potential energy interactions, chemical reactions and many others. It should be emphasized that while hosting a broader and richer phenomenology than “plain” hydrodynamics, generalized hydrodynamics still fits the hydrodynamic picture of weak departure from suitably generalized local equilibria. This class is all but an academic curiosity; for instance, it is central to the fast-growing science of Soft Matter, a scientific discipline which has received an impressive boost in the past decades, under the drive of micro- and nanotechnological developments and major strides in biology and life sciences at large.

scholarly journals A permeation-diffusion-reaction model of gas transport in cellular tissue of plant materials

2006 ◽  
Vol 57 (15) ◽  
pp. 4215-4224 ◽  
Author(s):  
Q. T. Ho ◽  
B. E. Verlinden ◽  
P. Verboven ◽  
S. Vandewalle ◽  
B. M. Nicolai
Keyword(s):  
Gas Transport ◽  
Cellular Tissue ◽  
Reaction Model ◽  
Diffusion Reaction ◽  
Plant Materials

Diffusion-reaction model for ASR

2014 ◽  
pp. 639-648 ◽  
Author(s):  
J Liaudat ◽  
C López ◽  
I Carol
Keyword(s):  
Reaction Model ◽  
Diffusion Reaction

scholarly journals Fractal diffusion-reaction model for a porous electrode

2021 ◽  
pp. 26-26
Author(s):  
Ling Lin ◽  
Yun Qiao
Keyword(s):  
Surface Morphology ◽  
Porous Electrode ◽  
Enzymatic Reaction ◽  
Bright Light ◽  
Reaction Model ◽  
Solution Procedure ◽  
Diffusion Reaction ◽  
Fast Diffusion ◽  
Fractal Derivative ◽  
Intuitive Grasp

Fractal modifications of Fick?s laws are discussed by taking into account the electrode?s porous structure, and a fractal derivative model for diffusion-reaction process in a thin film of an amperometric enzymatic reaction is established. Particular attention is paid to giving an intuitive grasp for its fractal variational principle and its solution procedure. Extremely fast or extremely slow diffusion process can be achieved by suitable control of the electrode?s surface morphology, a sponge-like surface leads to an extremely fast diffusion, while a lotus-leaf-like uneven surface predicts an extremely slow process. This paper sheds a bright light on an optimal design of an electrode?s surface morphology.

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