Justin Sadler

Pressure drop across capillary hole in spinneret

Discussion created by Justin Sadler on May 8, 2020
Latest reply on May 12, 2020 by Justin Sadler

A melt spinning process typically can require quite high pressures to extrude polymer melt of high viscosity through a spinneret.  Literature for process I have found seems to show 5k - 10k psi pressure across spinneret not uncommon.


I did a hand calc using the Hagen-Poiseuille law and came to around 5000 psi which is alignment with literature.


When I perform a CFD simulation, I get around 40k psi across spinneret.  I am not sure if I am not setting up flow simulation correctly or am missing something from a fluid mechanics standpoint. 


The study is a single 55micron (0.055mm) bore in diameter x 0.220 mm long (4X diameter).  Inlet velocity assumed 10 m/min in both the hand calcs and simulation.  Standard atmosphere assumed at capillary exit.


Attached is an image from simulation showing cross section.


Any help or suggestions for better understanding pressure drop in CFD would be appreciated.