Pinch-off masses of very viscous fluids extruded from dies of arbitrary shape

The extrusion of slender very viscous fluid cylinders from dies of arbitrary geometry is modeled to approximate the mass of the first drop to pinch off. The model neglects inertia, which, although important to the dynamics near pinch-off, does not have a significant impact on the drop mass. Extrudate swell is also assumed to be negligible. The model is able to compute the pinch-off mass for fluid cylinders with cross-sectional geometries of any connectivity. By way of illustration, pinchoff masses are computed for epicycloidal cross sections, two touching circular rods, and circular cylinders with a single circular hole placed both centrally and off-centre. It is shown that the drop mass may be controlled by altering either the extrusion conditions or the die geometry. Published by AIP Publishing.