I would like to calculate pressure drop rate across a valve,..... Material is a "non-soluble" polymer melt dispersed in water.....When the solution is released at high temperature from a valve I would like to calculate pressure drop rate.... Question is should we be using non-newtonian formula (as polymer melt behaves as non-newtonian) or newtonian formula (as water is involved)?????? Water is infact released in form of water and vapour along with the polymer melt..Potentially water is the driving force behind driving the melt across the valve and the so called mixture would behave newtonian? Please assist and let me know which would be the scientifically correct way!!