A practical way to model convection in non-agitated electrolytes

Долгих, О. В.; Demeter, A.; Bastos, A.C.; Ţopa, Vasile; Deconinck, Johan

doi:10.1016/j.elecom.2013.10.002

Cited by 10 publications

(8 citation statements)

References 11 publications

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“…Spontaneous convection is not considered in this work, as its effects have been discussed in detail in numerous papers in the past. 11, [23][24][25][26][27][28][29][30] For the diffusion-only simulations of currents at electrodes of different sizes: 250µm, 1.5mm and 4.0mm, all of which were often described as macroelectrodes and hence the radial contribution are often neglected. 25,[43][44][45] However it has been previously reported by our group using cyclic voltammetry 14 and is reinforced here using chronoamperometry that it is not completely true, and that the currents exceeding that predicted by the Cottrell equation are observed because of this radial diffusion, the so called edge effect.…”

Section: Effects On Chronoamperometric Resultsmentioning

confidence: 99%

Advancing from Rules of Thumb: Quantifying the Effects of Small Density Changes in Mass Transport to Electrodes. Understanding Natural Convection

et al. 2015

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Understanding mass transport is prerequisite to all quantitative analysis of electrochemical experiments. While the contribution of diffusion is well understood, the influence of density gradient-driven natural convection on the mass transport in electrochemical systems is not. To date, it has been assumed to be relevant only for high concentrations of redox-active species and at long experimental time scales. If unjustified, this assumption risks misinterpretation of analytical data obtained from scanning electrochemical microscopy (SECM) and generator-collector experiments, as well as analytical sensors utilizing macroelectrodes/microelectrode arrays. It also affects the results expected from electrodeposition. On the basis of numerical simulation, herein it is demonstrated that even at less than 10 mM concentrations and short experimental times of tens of seconds, density gradient-driven natural convection significantly affects mass transport. This is evident from in-depth numerical simulation for the oxidation of hexacyanoferrate (II) at various electrode sizes and electrode orientations. In each case, the induced convection and its influence on the diffusion layer established near the electrode are illustrated by maps of the velocity fields and concentration distributions evolving with time. The effects of natural convection on mass transport and chronoamperometric currents are thus quantified and discussed for the different cases studied.

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Section: Effects On Chronoamperometric Resultsmentioning

confidence: 99%

Advancing from Rules of Thumb: Quantifying the Effects of Small Density Changes in Mass Transport to Electrodes. Understanding Natural Convection

et al. 2015

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“…The rate coefficients of reactions (33) are calculated based on the imposed bulk concentrations and on Equation (17).…”

Section: Setup Of the Modelmentioning

confidence: 99%

A simulation study of steric effects on the anodic dissolution at high current densities

Köhn

Laethem

Deconinck

et al. 2020

Materials & Corrosion

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Electrochemical machining (ECM) and electropolishing are examples of anodic dissolution used in a wide variety of applications. Proper simulations of ECM require the establishment of a so-called gel layer of liquid metal salt, responsible for the depletion of water close to the surface such that the oxygen evolution is reduced. However, this effect is neglected in many simulation efforts, although it is significant to improve the accuracy of the machining process. Some authors consider this effect by an engineered "water-repelling" function that depends on the local metal ion concentration. As an alternative, we discuss the theoretical description and the implementation of modified Poisson-Nernst-Planck equations taking into account expressions in which each ion has its own maximum concentration and corresponding steric limit. We investigate a basic system of water, sodium chloride, and iron ions. Simulations pending on the local metal ion concentration for current densities show that the modified model works; steric effects become important for large current densities and the formation of a resistive gel layer is responsible for the reduction of water at the electrode. We observe that the electrostatic potential resulting from space charge effects is not affected by implementing the different species sizes. Further research is needed to explore the applicability of industrial simulation tools.

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“…The last term is a so called micro‐convection term, which describes a small motion of species due to the temperature gradient, vibrations, etc. The concept of micro‐convection is first introduced by Amatore et al and later further developed by some of the authors in a recent publication . In that work a correction is proposed for when multiple species are considered and the micro‐convection term has to become species independent.…”

Section: Simulations On the Micro‐scale: Multi‐ion Transport And Reacmentioning

confidence: 99%

“…The height of the domain represents the electrolyte layer thickness. Due to the presence of micro‐convection, electrolyte is well‐mixed already at a distance > 3 δ ref and can be considered as a bulk solution . Hence, 1 mm high domain is a good approximation for immersed conditions.…”

Section: Simulations On the Micro‐scale: Multi‐ion Transport And Reacmentioning

confidence: 99%

“…They introduced an artificial flow to mimic the natural convection in the electrolyte, which avoids flow calculations and simplifies the calculations. Dolgikh et al have applied the concept of the micro‐turbulent diffusion term to take the natural convection and diffusion layer into account. Their approach consists in making a modification to each diffusion coefficient.…”

Section: Introductionmentioning

confidence: 99%

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Corrosion protection of steel cut‐edges by hot‐dip galvanized Al(Zn,Mg) coatings in 1 wt% NaCl: Part II. Numerical simulations

Долгих

Simillion

Lamaka

et al. 2019

Materials & Corrosion

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In this paper a mechanistic model is elaborated to simulate the corrosion behavior of aluminum–zinc–magnesium coatings on steel. The model is based on the mass transport and reactions of the ions in the electrolyte (MITReM). The finite element method has been used, which allows to perform time‐dependent simulations with micrometer scale to study local corrosion effects. The formation of corrosion products and the prediction of electrolyte concentration distributions are compared for different metallic coating compositions. The spatial and temporal simulation of complex precipitates provides an additional tool to validate the model through corrosion product characterization. The simulation results are compared to experimental observations, presented in part I of this paper. The MITReM simulations are limited to the micro‐scale and therefore to small geometries. A link is made with the potential model which can be applied on macro‐scale objects. A qualitative agreement is found between the simulations at both scales and the experiments. Further quantification of this model would optimize the simulations for material design and for predictive maintenance.

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A practical way to model convection in non-agitated electrolytes

Cited by 10 publications

References 11 publications

Advancing from Rules of Thumb: Quantifying the Effects of Small Density Changes in Mass Transport to Electrodes. Understanding Natural Convection

Advancing from Rules of Thumb: Quantifying the Effects of Small Density Changes in Mass Transport to Electrodes. Understanding Natural Convection

A simulation study of steric effects on the anodic dissolution at high current densities

Corrosion protection of steel cut‐edges by hot‐dip galvanized Al(Zn,Mg) coatings in 1 wt% NaCl: Part II. Numerical simulations

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