Growth of non-axisymmetric disturbances of the free surface in the filament stretching rheometer: experiments and simulation

A filament stretching rheometer has been equipped with a bottom plate with a number of equally distributed perturbations of the circular rim. The temporal development of the resulting disturbance of the meniscus is followed with video recording and with simulations. At high strain rates the surface perturbations grow into a number of fluid columns. It is shown that the growth is associated with strain hardening of the material. The relevant Deborah number is the product of a time constant associated with the non-linear properties of the fluid and the imposed extension rate. (C) 2002 Elsevier Science B.V. All rights reserved.