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Search Publications by: Geoffrey B. McFadden ()

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Displaying 26 - 50 of 96

Bending of a Bimetallic Beam due to the Kirkendall Effect

January 1, 2010
Author(s)
William J. Boettinger, Geoffrey B. McFadden
The time dependent bending of single phase and two phase bimetal strips due to interdiffusion is computed. The model couples simple beam theory and diffusion, the bending being due to the creation and /annihilation of vacancies necessitated by unequal

Design of the DEMO Fusion Reactor Following ITER

July 1, 2009
Author(s)
Geoffrey B. McFadden, Paul R. Garabedian
Runs of the NSTAB equilibrium and stability code show there are many 3D solutions of the advanced tokamak problem subject to axially symmetric boundary conditions. These numerical simulations based on mathematical equations in conservation form predict

The contribution of lipid layer movement to tear film thinning and breakup

June 15, 2009
Author(s)
Geoffrey B. McFadden, Christopher Smith, Barbara A. Fink, Jason J. Nichols, Richard J. Braun
The purpose of this study is to investigate the origin of the tear film thinning between blinks, which can lead to tear film breakup and ocular surface damage. Two mechanisms of thinning are considered: "tangential flow" of the tear film along the surface

Onset of Oscillatory Convection in Two Liquid Layers with Phase Change

March 2, 2009
Author(s)
Geoffrey B. McFadden, Sam R. Coriell
We perform linear stability calculations for horizontal fluid bilayers that can undergo a phase transformation in the presence of a vertical temperature gradient. We reconsider the oscillatory instability calculated by Huang and Joseph [J. Fluid Mech. 242

Grain Size Distribution in Two Dimensions in the Long Time Limit

July 8, 2008
Author(s)
Geoffrey B. McFadden, C.S. Pande, K.P. Cooper
It is shown that the inclusion of a "noise" term in the growth rate of individual grains leads to a stochastic model that provides a more realistic description of grain growth phenomenon. The resulting Fokker-Planck equation for the grain size distribution

Instability in Pipe Flow

January 15, 2008
Author(s)
David Cotrell, Geoffrey B. McFadden, W. E. Alley, B. J. Alder
An axisymmetric linear stability analysis is carried out for flow driven by an axial pressure gradient in a pipe with axisymmetric and axially-periodic radius variation (i.e., axial corrugation). The steady base flow is assumed to be axisymmetric and

Convective Instabilities in Two Liquid Layers

January 1, 2007
Author(s)
Geoffrey B. McFadden, Sam R. Coriell, Katharine F. Gurski, David Cotrell
We perform linear stability calculations for horizontal fluid bilayers, taking into account both buoyancy effects and thermocapillary effects in the presence of a vertical temperature gradient. To help understand the mechanisms driving the instability we

Onset of Convection in Two Liquid Layers with Phase Change

January 1, 2007
Author(s)
Geoffrey B. McFadden, Sam R. Coriell, Katharine F. Gurski, David Cotrell
We perform linear stability calculations for horizontal fluid bilayers that can undergo a phase transformation, taking into account both buoyancy effects and thermocapillary effects. We compare the familiar case of the stability of two immiscible fluids in

Numerical Modeling of Diffusion-Induced Deformation

September 11, 2006
Author(s)
J A. Dantzig, William J. Boettinger, James A. Warren, Geoffrey B. McFadden, Sam R. Coriell, R F. Sekerka
We present a numerical approach to modeling the deformation induced the the Kirkendall effect in binary alloys. The governing equations for isothermal binary diffusion are formulated with respect to inert markers and also with respect to the volume

Phase-Field Modeling of Solidification Under Stress

January 2, 2006
Author(s)
Julia Slutsker, K Thornton, Alexander Roytburd, James A. Warren, Geoffrey B. McFadden, P W. Voorhees
A phase-field model that includes the stress field during non-isothermal phase transformation of a single-vomponent system has been developed. The model has been applied to the solidification and melting of confined spherical volumes, where sharp interface

Phase-Field Modeling of Solidification under Stress

January 1, 2006
Author(s)
J Slutsker, K Thornton, Alexander Roytburd, A Warren, Geoffrey B. McFadden, P W. Voorhees
Effective visualizations can help researchers obtain a more complete understanding of high-level mathematical functions that arise in mathematics, statistics, physics, fluid dynamics and other fields of the mathematical and physical sciences. Accordingly

Linear Stability of Cylindrical Couette Flow in the Convection Regime

October 1, 2005
Author(s)
M E. Ali, Geoffrey B. McFadden
Instability of steady circular Couette flow with radial heating across a vertically oriented annulus with inner cylinder rotating and outer cylinder stationary is investigated using linear stability analysis. The convection regime base flow is developed

Lateral Deformation of Diffusion Couples

April 1, 2005
Author(s)
William J. Boettinger, Geoffrey B. McFadden, Sam R. Coriell, R F. Sekerka, James A. Warren
A model is proposed to describe the shape change (displacement field) of a binary diffusion couple when the intrinsic (lattice) diffusivities of the two substitutional atomic species differ. As for the Kirkendall effect, the displacement is due the

Phase Field Modeling of Solidification Under Stress

July 1, 2004
Author(s)
Julia Slutsker, Alexander L. Roytburd, James A. Warren, Geoffrey B. McFadden, William J. Boettinger
A phase-field model that includes stress field during non-isothermal solidification of a one-component system has been developed. The model has been applied to solidification and melting of confined spherical volumes. It has been shown that at some

Phase-Field Modeling for Eutectic Solidification

April 1, 2004
Author(s)
Jonathan E. Guyer, William J. Boettinger, James A. Warren, Geoffrey B. McFadden
A diffuse interface (phase field) model for a simple electrochemical system is developed. We describe the minimal set of components needed to model an electrochemical interface and present a Lagrangian derivation of te governing equations. With a simple

Centrifugal Buoyancy Effects on the Linear Stability of Sprial Poiseuille Flow

February 1, 2004
Author(s)
David Cotrell, Geoffrey B. McFadden
For fluid flow in an annulus driven by the combination of an axial pressure gradient, rotation of the inner and outer cylinders, and a radial temperature gradient (spiral Poiseuille flow with a radial temperature gradient), we are investigating the

Phase Field Modeling of Electrochemistry. I. Equilibrium

February 1, 2004
Author(s)
Jonathan E. Guyer, William J. Boettinger, James A. Warren, Geoffrey B. McFadden
A diffuse interface (phase field) model for an electrochemical system is developed. We describe the minimal set of components needed to model an electrochemical interface and present a variational derivation of the governing equations. With a simple set of