Simulation of pressure‐tooling wire‐coating flow with Phan‐Thien/Tanner models

Abstract

SUMMARYAnnular pressure-tooling extrusion is simulated for a low density polymer melt using a Taylor-PetrovGalerkin ÿnite element scheme. This represents industrial-scale wire-coating. Viscoelastic uids are modeled via three forms of Phan-Thien=Tanner (PTT) constitutive laws employed for short-die and full speciÿcation pressure-tooling. E ects of variation in Weissenberg number (We) and polymeric viscosity are investigated. Particular attention is paid to mesh reÿnement to predict accurate results. The impact of variation in shear-thinning and strain-softening properties is considered upon the modelling predictions. For the short-die ow, the in uence of the lack of strain softening is identiÿed. For the full-die ow and more severe deformation rates, the linear PTT model failed to converge. In contrast, the exponential PTT model is found to be more stable numerically and to adequately re ect the material response. Comparing short-die and full-die pressure-tooling results, shear rates increase 10-fold, while strain rates increase one hundred times.

Simulation of pressure‐ and tube‐tooling wire‐coating flows through distributed computation

“…Profiles on the wire are relatively smooth, in contrast. We have observed in our earlier work (Ngamaramvaranggul and Webster, 2002), that the strain-softening response of the EPTT model, stabilises 474 stress profiles. This stands in stark contrast to models that support strainhardening.…”

“…Mesh refinement considerations follow our previous studies (Ngamaramvaranggul and Webster, 2002;Ngamaramvaranggul and Webster, 2000b;Ngamaramvaranggul and Webster, 2001), where the fine mesh of Figure 2b is found suitable. The flowrate through the die is fixed by the fully-developed annular inlet flow profile under pressure-driven conditions.…”

“…6.2 Full-die, pressure-tooling Following our earlier study on mesh convergence (Ngamaramvaranggul and Webster, 2002), for this problem our results are plotted upon the biased fine mesh of Figure 3b, with identical parameter settings as for the short-die flow. The zonal refinements are outlined in Table II, with greatest density and bias in the land and die-exit regions.…”

Numerical simulation of polymer foaming process in extrusion flow

“…Apart from the SVM, the other models have been used extensively in the simulations of extrusion flow processes and their merits and demerits can be found in the literature Ngamaramvaranggul and Webster, 2002;Debbaut and Marchal, 2008;Mu and Zhao, 2008;Otsuki et al, 1999;Tanner and Nasseri, 2003). Unlike some Table 1 Relaxation spectrum for LDPE sample.…”

Distributed parallel computation for complex rotational flows of non‐Newtonian fluids

“…It is a technically challenging problem to accom- 2 ) and large µ 1 (approaching unity) solutions has been demonstrated elsewhere, under industrial level requirements [24][25][26]. Reaching such high elasticity levels is an open and current research topic (see review articles, [27][28][29][30]).…”