Material characterization of polymer solutions and surfactant systems using free surface measurements

Polymer solutions and surfactant systems are widely used in many manufacturing and agriculture processes. To model these processes, one must know the properties of the fluid (e.g. viscosity, relaxation time, retardation time) under a range of flow conditions (elongational flow, shear flow, filament stretching flow, etc.). The research of this dissertation characterizes the material properties of test fluids in different flows based on free surface measurements. The measured free surface profiles of a test flow are filtered and numerically manipulated in Part I to obtain the smooth profile and first and second numerical derivatives of the profile, which are subsequently used in the inverse problems of material characterizations. In Part II of this dissertation, the spinline elongational, filament stretching, and shear characterizations of a viscoelastic test fluid are obtained in the contexts of one, two, and three-mode Oldroyd fluid-B constitutive models, one and two-mode Giesekus models, and one-mode FENE-P model. The capability of each of the six constitutive models to predict the material behavior of test fluid is investigated by comparing the quantities from constitutive models with the measurements from experiments. In Part III the measurement of the dynamic evolution of surface tension is characterized in the millisecond scale for agricultural surfactant systems, utilizing free surface measurements of oscillating jets.