We investigate the transient viscoelastic response of weakly strain-hardening fluids to imposed elongational deformation in filament stretching devices. We combine timedependent finite-element simulations with quantitative experimental measurements on a rheologically well-characterized test fluid to investigate how well the device reproduces the ideal transient uniaxial extensional viscosity pr...

Plastics extrusion is a manufacturing process suitable for continuous profiles such as floor skirtings, window frames, and pipes. In industrial applications, extrusion is a large-scale process, financially attractive only for mass products. This is due to the time consuming and costly regulation of the extrusion process and especially, the design of an extrusion die which relies on running-in e...

We numerically study the effect of solid boundaries on the swimming behavior of a motile microorganism in viscoelastic media. Understanding the swimmer-wall hydrodynamic interactions is crucial to elucidate the adhesion of bacterial cells to nearby substrates which is precursor to the formation of the microbial biofilms. The microorganism is simulated using a squirmer model that captures the ma...

Viscoelastic fluids are non-Newtonian that exhibit both "viscous" and "elastic" characteristics in virtue of mechanisms to store energy produce entropy. Usually the storage properties such modelled using same concepts as classical theory nonlinear solids. Recently new models for elastic solids have been successfully developed by appealing implicit constitutive relations, these offer a different...

A numerical method for modeling time-dependent viscoelastic uid ow, Abstract A numerical method to solve a system of partial diierential equations (PDE), modeling time-dependent viscoelastic uid ow, is developed. The Upper Con-vected Maxwell (UCM) model, and the related Oldroyd-B and Giesekus models are used as constitutive equations, and a linear equation of state allows the uid to be slightly...

We present a new finite-difference formulation to update the conformation tensor in dumbbell models (e.g., Oldroyd-B, FENE-P, Giesekus) that guarantees positive eigenvalues of the tensor (i.e., the tensor remains positive definite) and prevents over-extension for finite-extensible models. The formulation is a generalization of the second-order, central difference scheme developed by Kurganov an...

In this paper, we study the dynamics of deformable cells in a channel flow of Newtonian and polymeric fluids and unravel the effects of deformability, elasticity, inertia, and size on the cell motion. We investigate the role of polymeric fluids on the cell migration behavior and the performance of inertial microfluidic devices. Our results show that the equilibrium position of the cell is on th...