Peter Wapperom, Adrien Leygue, and Roland Keunings
Numerical simulation of large amplitude oscillatory shear
of a high-density polyethylene melt using the MSF model
Journal of Non-Newtonian Fluid Mechanics 130 (2005) 63-76
We study the flow response in large amplitude oscillatory shear
of the molecular stress function (MSF) model that has recently been
proposed by Wagner et al. [J. Rheol., 45 (2001) 1387-1412].
The MSF model is derived from molecular theory and has only
two parameters to describe the nonlinear material response.
The model predictions are analysed in both the frequency and time domain.
It shows good agreement with experimental data for a linear
high density polyethylene melt.
At low and medium strains, MSF model predictions are in excellent agreement
with experimental data and predictions of a six-mode Giesekus model which
has six parameters to describe the nonlinear material response.
At medium strains, the basic Doi-Edwards model, which
has no nonlinear parameters, already underpredicts the data.
At high strains, the MSF model predictions agree slightly better with
the experimental data than the Giesekus model.
Surprisingly, however, it is the Doi-Edwards model
that shows excellent agreement with
experimental data at high strains. For the linear melt we consider,
it outperforms the models that have nonlinear parameters, both in the time
and frequency domain.
LAOS; integral MSF model; deformation field method;
linear polymer melts