Use of the finite element method to interpret viscous and viscoelastic effects in blade coating.

Coating thickness data and finite element simulations are presented for the blade coating of a series of Newtonian and non-Newtonian fluids. Experiments with non-Newtonian fluids having almost identical viscosity-shear rate behavior, but varying normal stress coefficients, make it possible to isolate nonlinear shear viscosity effects from "elastic" phenomena. Finite element simulations, which assume purely viscous behavior, are in good agreement with data for Newtonian and inelastic non-Newtonian fluids. Nonlinear (shear-thinning) viscosity causes an increase in coating thickness, relative to Newtonian fluids, but as the normal stress coefficient increases, coating thickness is reduced. A Boger fluid, with a nearly constant shear viscosity but a large normal stress coefficient, coats much thinner than a Newtonian fluid.