Abstract
Flow-induced birefringence and particle tracking velocimetry are used to investigate the lubricated flow of a low density polyethylene melt in a cross-slot geometry. The numerical predictions of the extended Pom-Pom (XPP) model in its original and modified (mXPP) version as well as those of the Giesekus model are analyzed along selected streamlines in two-dimensional (2D) complex flows involving a mixture of shear and planar extensional deformations at two Weissenberg numbers of W i = 21 and 29. Oil film light reflections perturbing the particle tracking velocimetry data analysis together with multiple orders of retardation occurring within the laser beam close to the stagnation point prevent a conclusive discrimination between the mentioned models. Although the agreement with the experimental data is mostly qualitative, the Pom-Pom model does not overestimate the data along the cross-slot symmetry lines contrary to what was observed in other cross-slot experiments without lubrication. This is a clear indicator that end effects play a central role in unlubricated cross-slot geometries having a large aspect ratio.
Original language | English (US) |
---|---|
Pages (from-to) | 52-64 |
Number of pages | 13 |
Journal | Journal of Non-Newtonian Fluid Mechanics |
Volume | 154 |
Issue number | 1 |
DOIs | |
State | Published - Sep 2008 |
Externally published | Yes |
All Science Journal Classification (ASJC) codes
- General Chemical Engineering
- General Materials Science
- Condensed Matter Physics
- Mechanical Engineering
- Applied Mathematics
Keywords
- End effects
- Flow-induced birefringence
- Lubrication
- Numerical simulations
- Particle tracking velocimetry
- Pom-pom models
- Stagnation flow