scholarly journals Lattice Boltzmann Computations of Transport Processes in Complex Hydrodynamics Systems

10.5772/30668 ◽  
2011 ◽  
Author(s):  
Zhiqiang Dong ◽  
Weizhong Li ◽  
Yongchen Song ◽  
Fangming Jiang
Keyword(s):  
Lattice Boltzmann ◽  
Transport Processes

Detailed Electrochemistry and Gas Transport in a SOFC Anode Using the Lattice Boltzmann Method

2006 ◽  
Author(s):  
Kyle N. Grew ◽  
Abhijit S. Joshi ◽  
Aldo A. Peracchio ◽  
Wilson K. S. Chiu
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Electrochemical Reaction ◽  
Coupled Model ◽  
Transport Processes ◽  
Flux Boundary Conditions ◽  
Sofc Anode ◽  
Boltzmann Method ◽  
Electrochemical Model ◽  
And Diffusion

A coupled electrochemical reaction and diffusion model has been developed and verified for investigation of mass transport processes in Solid Oxide Fuel Cell (SOFC) anode triple-phase boundary (TPB) regions. The coupled model utilizes a two-dimensional (2D), multi-species Lattice Boltzmann Method (LBM) to model the diffusion process. The electrochemical model is coupled through localized flux boundary conditions and is a function of applied activation overpotential and the localized hydrogen and water mole fractions. This model is designed so that the effects of the anode microstructure within TPB regions can be examined in detail. Results are provided for the independent validation of the electrochemical and diffusion sub-models, as well as for the coupled model. An analysis on a single closed pore is completed and validated with a Fick's law solution. A competition between the electrochemical reaction rate and the rate of mass transfer is observed to be dependent on inlet hydrogen mole fraction. The developed model is presented such that future studies on SOFC anode microstructures can be completed.

Evaluation of Lattice Boltzmann Method for Reaction-Diffusion Process in a Porous SOFC Anode Microstructure

2012 ◽  
Author(s):  
Hedvig Paradis ◽  
Bengt Sundén
Keyword(s):  
Porous Media ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Reaction Diffusion ◽  
Reaction Rates ◽  
Transport Processes ◽  
Microscopic Level ◽  
Reaction Diffusion Equation ◽  
Interaction Sites ◽  
Boltzmann Method

In the microscale structure of a porous electrode, the transport processes are among the least understood areas of SOFC. The purpose of this study is to evaluate the Lattice Boltzmann Method (LBM) for a porous microscopic media and investigate mass transfer processes with electrochemical reactions by LBM at a mesoscopic and microscopic level. Part of the anode structure of an SOFC for two components is evaluated qualitatively for two different geometry configurations of the porous media. The reaction-diffusion equation has been implemented in the particle distribution function used in LBM. The LBM code in this study is written in the programs MATLAB and Palabos. It has here been shown that LBM can be effectively used at a mesoscopic level ranging down to a microscopic level and proven to effectively take care of the interaction between the particles and the walls of the porous media. LBM can also handle the implementation of reaction rates where these can be locally specified or as a general source term. It is concluded that LBM can be valuable for evaluating the risk of local harming spots within the porous structure to reduce these interaction sites. In future studies, the information gained from the microscale modeling can be coupled to a macroscale CFD model and help in development of a smooth structure for interaction of the reforming reaction and the electrochemical reaction rates. This can in turn improve the cell performance.

An X-Ray Tomography Based Lattice Boltzmann Simulation Study on Gas Diffusion Layers of Polymer Electrolyte Fuel Cells

2010 ◽  
Vol 7 (3) ◽  
Author(s):  
Pratap Rama ◽  
Yu Liu ◽  
Rui Chen ◽  
Hossein Ostadi ◽  
Kyle Jiang ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Lattice Boltzmann ◽  
Gas Diffusion ◽  
Transport Processes ◽  
Polymer Electrolyte Fuel Cell ◽  
Absolute Permeability ◽  
Carbon Paper ◽  
X Ray ◽  
Microscale Transport

This work reports a feasibility study into the combined full morphological reconstruction of fuel cell structures using X-ray computed micro- and nanotomography and lattice Boltzmann modeling to simulate fluid flow at pore scale in porous materials. This work provides a description of how the two techniques have been adapted to simulate gas movement through a carbon paper gas diffusion layer (GDL). The validation work demonstrates that the difference between the simulated and measured absolute permeability of air is 3%. The current study elucidates the potential to enable improvements in GDL design, material composition, and cell design to be realized through a greater understanding of the nano- and microscale transport processes occurring within the polymer electrolyte fuel cell.

scholarly journals 3D analysis, modeling and simulation of transport processes in compressed fibrous microstructures, using the Lattice Boltzmann method

2013 ◽  
Vol 110 ◽  
pp. 325-334 ◽  
Author(s):  
Dieter Froning ◽  
Jan Brinkmann ◽  
Uwe Reimer ◽  
Volker Schmidt ◽  
Werner Lehnert ◽  
...  
Keyword(s):  
Modeling And Simulation ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Transport Processes ◽  
3D Analysis ◽  
Boltzmann Method

LATTICE BOLTZMANN SIMULATION OF MOMENTUM AND ENERGY TRANSFER IN A POROUS MEDIUM

2005 ◽  
Vol 19 (28n29) ◽  
pp. 1531-1534 ◽  
Author(s):  
YOUSHENG XU ◽  
YANG LIU ◽  
GUOXIANG HUANG
Keyword(s):  
Porous Medium ◽  
Energy Transfer ◽  
Lattice Boltzmann ◽  
Energy Transport ◽  
Transport Processes ◽  
Air Conditioning System ◽  
Flow And Heat Transfer ◽  
Lattice Boltzmann Simulation ◽  
Darcy Equations ◽  
Boltzmann Method

The fluid flow and heat transfer in porous media has wide applications in oil industry and air conditioning system. In this study the momentum and energy transport processes in a porous medium are numerically simulated. The Brinkman-Forchheimer-extended Darcy equations and energy equation are solved using single lattice-Boltzmann method (LBM). As a first attempt, a benchmark problem is studied, i.e., momentum and energy transfer in a rectangular enclosure with differentially heated vertical walls. The effect of permeability on the critical Rayleigh numbers, the temperature distribution and flow field is discussed.

Perspectives on Lattice Boltzmann Modeling of Transport Processes With Electrochemical Reactions in SOFCs

2013 ◽  
Author(s):  
Hedvig Paradis ◽  
Martin Andersson ◽  
Bengt Sundén
Keyword(s):  
Current Density ◽  
Lattice Boltzmann ◽  
Active Sites ◽  
Fluid Dynamic ◽  
Computational Procedure ◽  
Transport Processes ◽  
Computational Method ◽  
Electrochemical Reactions ◽  
Active Reaction ◽  
Porous Domain

Lattice Boltzmann method (LBM) is alternative computational method to the traditional computational fluid dynamic (CFD) methods. LBM has the ability to with straightforward computational procedure to handle the detail activity at microscale well for simulation of different transport processes. In this study the focus is on the effects of electrochemical reactions and transport processes in an anode of Solid Oxide Fuel Cell (SOFC) at microscale. The electrochemical reactions are captured at specific sites where the so-called three-phase boundaries (TPB) are present. The porous modeling domain is created with randomly placed spheres of two different sizes to resemble the materials Ni and YSZ for the part of the anode close to the electrolyte. The simulated transport processes are mass, heat, momentum and charge transfer with electrochemical reactions. These are evaluated with the software tools Palabos and MATLAB. It is concluded that LBM can be used to evaluate the microscopic effect of electrochemical reactions on the transport processes. Case studies are carried out on the current density and the concentration distribution of H2 by changing the porosity, percentage of active reaction sites and particle size. It is shown that an increase in porosity decreases the current density throughout the porous domain while an increase in percentage of active sites has a positive increase in current density. The concentration of H2 decreases throughout the cell when the porosity is increased from 30% to 50%. As a suggestion for future improvements, it might be a good idea to have the active reaction sites placed out in a graded manner with a high density of reaction sites where it is needed.

Lattice Boltzmann Simulation of Transport Phenomena in Nanostructured Cathode Catalyst Layer for Proton Exchange Membrane Fuel Cells

2012 ◽  
Vol 1384 ◽  
Author(s):  
Christopher D. Stiles ◽  
Yongqiang Xue
Keyword(s):  
Mass Transport ◽  
Lattice Boltzmann ◽  
Proton Exchange Membrane ◽  
Catalyst Layer ◽  
Transport Processes ◽  
Proton Exchange ◽  
Pt Catalyst ◽  
Cathode Catalyst ◽  
Cathode Catalyst Layer ◽  
Exchange Membrane

ABSTRACTA multi-component, multiple-relaxation-time (MRT) lattice Boltzmann (LB) model has been employed to study transport processes in the nanostructured cathode catalyst layer of a prototype proton exchange membrane (PEM) fuel cell. The electrode consists of an array of ordered and aligned nanorods that are continuously coated with platinum (Pt). The effect of spacing between the nanorods was studied. Simulation results showed that smaller spacing in nanorods leads to lower utilization of the Pt catalyst due to O2 mass transport limitations. Results from the LB model were found to be in good agreement with the continuum model using the finite element method (FEM) with the same boundary conditions until the systems reached the O2 mass transport limited regions, where the solutions diverged.

Coupled lattice Boltzmann simulation method for bidomain type models in cardiac electrophysiology with multiple time-delays

2019 ◽  
Vol 14 (2) ◽  
pp. 207
Author(s):  
S. Corre ◽  
A. Belmiloudi
Keyword(s):  
Differential Equations ◽  
Lattice Boltzmann ◽  
Time Delays ◽  
Cardiac Electrophysiology ◽  
Heart Rhythm ◽  
Transport Processes ◽  
Coupled Systems ◽  
Multiple Time ◽  
Multiple Time Delays ◽  
Reaction Diffusion Model

In this work, we propose a mathematical model of the cardiac electrophysiology which take into account time delays in signal transmission, in order to capture the whole activities of macro- to micro-scale transport processes, and use this model to analyze the propagation of electrophysiological waves in the heart by using a developed coupling Lattice Boltzmann Method (LBM). The propagation of electrical activity in the heart is mathematically modeled by a modified bidomain system. As transmembrane potential evolves, the domain has anisotropical properties which are transposed into intracellular and extracellular conductivity. The new bidomain system is a multi-scale, stiff and strongly nonlinear coupled reaction-diffusion model in the shape of a set of ordinary differential equations coupled with a set of partial differential equations with multiple time delays. Due to delays, dynamic and geometry complexity, numerical simulation and implementation of this type of coupled systems are very ambitious mathematical and computational problems but are crucial in several biomedical applications. We introduce a modified LBM scheme, reliable, efficient, stable and easy to implement in the context of such bidomain systems with multiple time delays. Numerical tests to confirm effectiveness and accuracy of our approach are provided and, the influence and impact of delays to restore normal heart rhythm are analyzed.

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