Computational Fluid Mechanics, Macromolecular Fluid Flow, Transport Phenomena, and Stochastic Simulations
Liquids that contain or are composed of macromolecules often have particular properties that can be exploited for engineering applications. The development of new polymeric materials and processes are of industrial importance with applications in polymer processing, biological fluids, paints, coatings, oil recovery, and many others. Many of these applications touch our everyday lives. Central to developing these materials and processes is understanding the molecular behavior of these liquids. There has been a great deal of progress made in this field through the use of statistical mechanics, kinetic theory, and computer simulation, yet recent advances in engineering science and technology have created opportunities to study these materials in detail at the molecular level. The development of these advances is just beginning; my research program is aimed at using emerging technologies to more completely describe polymeric systems.
Computer simulation techniques are powerful tools that can be used to investigate the behavior and properties of macromolecules. For example, we have simulated the conformation of a polymer as it moves through a pore in a membrane during ultrafiltration. Solute-membrane interaction can lead to pore plugging or membrane fouling, and therefore severely limit the productivity of many ultrafiltration processes. The insight gained from simulations will aid in the design of separation membranes.
Also, simulations yield detailed velocity, stress, and temperature profiles. This information is essential in the design of such polymer processing applications as injection molding, die extrusion, calendaring, and coating. Numerical simulation can be used to avoid the expensive prototype-test-redesign cycle.
It is essential to compare the results of simulations against experimental observation. The optical technique of laser Doppler velocimetry (LDV) is an experimental technique that can measure fluid velocities accurately, rapidly, and with a high degree of spatial resolution. The range of application for LDV is quite broad, since detailed velocity data can be obtained in steady or unsteady flows, flows in conduits, flows around bodies, and many other flow geometries. LDV can also be used to identify anomalous flow behavior, for example, secondary flows caused by the elastic nature of non-Newtonian liquids or backflow near the exit of an extruder, which may not have been predicted by theory.
Selected Recent Publications:
(1) Asymptotic analysis of the L closure for one-dimensional dumbbell models of transient stress in a suddenly started elongational flow," Nitsche, L.C., W. Zhang, and L.E. Wedgewood (Accepted in JNNFM 2005)
(2) "Stagnation Flow Studies of Polymer Solutions in a 2D System," K.S. Joshi and L.E. Wedgewood, Appl. Rheol.13:4 (2003) 174-182
(3) "Effects of Viscosity Variations in Steady and Oscillatory Couette Flow," D.I. Bou-Relan, K.S. Joshi and L.E. Wedgewood, Chem. Eng. Comm., 190: 489-507 (2003)
(4) “Properties and Rheology of Coal-Water Mixtures Using Different Coals,” R. M. Turian, J. F. Attal, D. –J. Sung and L. E. Wedgewood, FUEL 81 (16): 2019-2033 NOV 2002
(5) “A network model with free-strand dynamics for polymer melts,” Maria Seimenis and L. E. Wedgewood, Rheol Acta (2002) 41: 93-102
(6) "An Objective Rotation Tensor Applied to Non-Newtonian Fluid Mechanics," L.E. Wedgewood, Rheol Acta, 38 (1999) 91-99.
(7) "Laser Doppler Measurements of Flow in a Cone-and-Plate Rheometer," Douglas Dudgeon and L.E. Wedgewood, Rheol Acta, 36 (1997) 28-37.
(8) "A finitely extensible network strand model with non-linear backbone forces and entanglement kinetics," K.R. Geurts and L.E. Wedgewood, J. Chem. Phys., 106 (1997) 339-346.
(9) "Stochastic Simulation of Transport Phenomena," L.E. Wedgewood and K.R. Geurts, Ind. Eng. Chem. Res., 34 (1995) 3437-3444.
(10) "A Non-Affine Network Model for Polymer Melts," L.E. Wedgewood and K.R. Geurts, Rheol. Acta, 34 (1995) 196-208.
(11) "A domain perturbation study of steady flow in a cone-and-plate rheometer of non-ideal geometry," D.J. Dudgeon and L.E. Wedgewood, Rheol. Acta, 33 (1994) 369-384.
(12) "Flow in the Misaligned Cone-and-Plate Rheometer," D.J. Dudgeon and L.E. Wedgewood, J. Non-Newtonian Fluid Mech., 48 (1993) 21-48.
(13) "Internal Viscosity in Polymer Kinetic Theory," Lewis E. Wedgewood, Rheol. Acta, 32 (1993) 405-417.
"Viscosity," L. E. Wedgewood, McGraw-Hill Encyclopedia of Science and Technology, on-line edition (2005)