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Rheology of Polymeric and Complex Nanostructured Fluids. Investigator: Ludwig C. Nitsche , Chemical Engineering Department Collaborator: Lewis E. Wedgewood, Chemical Engineering Department.
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Rheology of Polymeric and Complex Nanostructured Fluids Investigator: Ludwig C. Nitsche, Chemical Engineering Department Collaborator: Lewis E. Wedgewood, Chemical Engineering Department • Derive macroscopic constitutive laws from stylized molecular models of polymers and complex fluid substructure in dilute solution. • Obtain probability density functions describing external (translational) and internal (conformational) degrees of freedom of suspended bead-spring entities. • Manipulate complex fluids with flow geometry and external fields. Numerical versus asymptotic PDF’s for a linear-locked dumbbell Closure relations for the conformatioally averaged Smoluchowski equation • Numerical simulations by atomistic smoothed particle hydrodynamics (ASPH). • “Smart swarms” of particles solve the Smoluchowski equation for translational and conformational motions of dumbbell models of polymers in dilute solution. • Asymptotic theory (singular perturbations and multiple scales) consolidates numerics and extracts formulas for probability density profiles, scaling laws and rheological constitutive equations. • Developed model of cross-stream migration of polymers in flows with gradients in shear. • The first asymptotic PDF for the classic problem of FENE dumbbells stretching in elongational flows. • Rigorous basis for the recent “L-closure”, and analytical explanation for the numerically observed collapse of transient stress-birefringence curves for different polymer lengths.