For an unsteady process like injection molding process, is there a similarity between flow behavior and the power law model.
if your power law was determined for high flow rate, it is very likely
if your power law was determined with low volume flow rate, it should be OK
Flow rate (through reynolds number) strongly determines the fluid behavior.
Refers, for instance, to Colebrokes-Moody diagram for various laws and Re applying range.
As fluid should have an high viscosity, small variation of speed will create high modification of Reynolds number.
Section 8.1 of Chapter 8 (pp. 238 – 244) in the book A. V. Shenoy and D. R. Saini, Thermoplastic Melt Rheology and Processing, Marcel Dekker Inc., New York (1996), discusses injection molding and shows simplified calculations for mold-filling during non-isothermal flow of polymer melts. The derived equations are based on the modified Ostwald-de Waale power-law model which was found to fit best in the shear rate range from 10 – 103 sec-1.
thank you all for your reply. The equations based on modified Ostwald-de Waale power-law model is very useful.
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