| Numerical simulations have been performed to evaluate the applicability of the multimode Giesekus model in predicting the flow behavior of a rheologically well characterized low density polyethylene melt (LDPE) in a lubricated cross-slot channel. Specifically, the fidelity of the numerical results are established by detailed comparison with flow induced birefringence measurements in a new optical rheometer whose front and back viewing windows are lubricated to create an ideal two-dimensional flow kinematics that leads to the elimination of end effects commonly encountered in flow birefringence measurements. These comparisons demonstrate the ability of the multimode Giesekus model to accurately capture the flow characteristics at moderate Weissenberg numbers (Wi). However, the model predictions at large Wi are at best qualitative particularly in the vicinity of the stagnation point and the outflow channel. The inability of the simulations in predicting the stress profiles in the stagnation region is partly attributed to the inaccuracy of the experimental data resulting from multiple orders of retardation occurring within the measurement volume in these regions. Specifically, the laser beam diameter, together with lubricant reflections and data analysis issues render the current experimental protocol of limited value in characterizing the polymeric stresses in the vicinity and downstream of the stagnation point.
for LaTeX users @article{AAbedijaberi2009-48,
author = {A. Abedijaberi and J. Soulages and M. Kr\"oger and B. Khomami},
title = {Flow of branched polymer melts in a lubricated cross-slot channel: A combined computational and experimental study},
journal = {Rheol. Acta},
volume = {48},
pages = {97-108},
year = {2009}
}
\bibitem{AAbedijaberi2009-48} A. Abedijaberi, J. Soulages, M. Kr\"oger, B. Khomami,
Flow of branched polymer melts in a lubricated cross-slot channel: A combined computational and experimental study,
Rheol. Acta {\bf 48} (2009) 97-108.AAbedijaberi2009-48
A. Abedijaberi, J. Soulages, M. Kr\"oger, B. Khomami
Flow of branched polymer melts in a lubricated cross-slot channel: A combined computational and experimental study
Rheol. Acta,48,2009,97-108 |
mk@mat.ethz.ch
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