Pressure and shear flow singularities: Fluid splitting and printing nip hydrodynamics

A numerical simulation of the fluid flow in the gravure printing nip, based on a discontinuous Galerkin algorithm, is used to study the fluid-splitting process and the transition between point and lamella splitting. We study the pressure and shear singularities at the contact point of the printing cylinder and substrate as a function of the variable microscopic residual gap and variations of the printing fluid quantities introduced to the nip. As the hydrodynamic boundary value problem is ill-defined by the nip singularity, we enhance the simulation using renormalization group and algebraic scaling techniques in order to obtain a numerically stable and physically meaningful prediction. Our simulations are compared to analytical results from lubrication theory and to experimental observations on a gravure press.

Automated summary

A numerical simulation based on a discontinuous Galerkin algorithm is conducted to study the fluid splitting process and transition in the gravure printing nip. The pressure and shear singularities at the contact point between the printing cylinder and substrate are investigated by considering the variable microscopic residual gap and variations in the printing fluid quantities. Renormalization group and algebraic scaling techniques are applied to enhance the simulation and obtain numerically stable and physically meaningful predictions. The simulations are compared with analytical results and experimental observations.