Masters Theses

Alternative Title

3D transient simulation of an electrochemical magnetohydrodynamics cell with micro and millielectrode: a unified reconciliation of theory and experiment
3-D transient simulation of an electrochemical magnetohydrodynamics cell with micro and millielectrode: a unified reconciliation of theory and experiment

Abstract

"Even though electrochemically induced magnetohydrodynamic (MHD) convection is a straightforward inexpensive method for moving fluids in confined spaces as for example during electrodeposition, stripping voltammetry, or in microfluidics, efficient quantitative models only recently have begun to appear. This is traced to complex mathematics that have prevented development of analytical expressions, e.g., for mass-transfer limited currents in analogy to the well-known Levich equation for the rotating electrode. Thus, related literature expressions remain mainly phenomenological concerning particular cell geometries or applications. Here, using such reports as points of departure, we validate a computationally rigorous description of the magnetoelectrochemical problem and define the relative significance of all system parameters. For this we use a three-dimension transient numerical simulation and establish that the full problem is adequately described by the conservation of momentum (modified Navier-Stokes equation), conservation of mass, and conservation of species (Fick's second law augmented with convection). These three equations are coupled by the Faradaic current given as a function of the flux of the redox active species to the working electrode. Computations are performed in the regime of milli and microelectrodes ranging from 250 µm in diameter to 16 mm, both with and without a magnetic field. Millielectrodes without a magnetic field generate diffusion-controlled voltammograms, and with the magnetic field vector parallel to the electrode surface, generate sigmoidal-shaped steady-state voltammograms. The Lorentz force was applied to the whole solution, but migrational current was ignored, so only in the presence of a concentration gradient was the Lorentz force applied. This region is in the near field of the working electrode and renders the placement of the counter electrode unimportant. The limiting current generated captures most of the experimental observations"--Abstract, page iv.

Advisor(s)

Isaac, Kakkattukuzhy M.

Committee Member(s)

Nisbett, J. Keith
Leventis, Nicholas

Department(s)

Mechanical and Aerospace Engineering

Degree Name

M.S. in Mechanical Engineering

Sponsor(s)

National Science Foundation (U.S.)

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2012

Pagination

vii, 29 pages

Note about bibliography

Includes bibliographical references (pages 21-23).

Rights

© 2012 Cajon Gonzales, All rights reserved.

Document Type

Thesis - Restricted Access

File Type

text

Language

English

Library of Congress Subject Headings

Magnetohydrodynamics -- Mathematical models
Magnetohydrodynamics
Microelectrodes
Microelectronics

Thesis Number

T 9965

Print OCLC #

815969530

Electronic OCLC #

908691148

Link to Catalog Record

Electronic access to the full-text of this document is restricted to Missouri S&T users. Otherwise, request this publication directly from Missouri S&T Library or contact your local library.

http://laurel.lso.missouri.edu/record=b9390407~S5

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