Defining a material using two viscosity equations with two variables (presssure, temperature) with different conditions

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Hi,

I am trying to model supercritical carbon dioxide as fluid into a tube. when the simulation satrts the carbon dioxide is flowing as a gas but after the critical point it becomes supercritical. I have defined the viscosity in supercritical state using an analytical function but this function is not valid is the gaseous phase. I would like to add another equation dependent of pressure and temperature from start until the supercritical point. After this point, the viscosity should follow the equation for supercritical carbon dioxide. I don't know if this is possible and how I could model this. I hope someone could help me with this matter.

function1(p,T): p =1-73 bar T = 313-373 C

function2(p,T): p = 73-200 bar T = 313-373 C

I would like to thank you in advance.


0 Replies Last Post Sep 30, 2022, 9:20 a.m. EDT
COMSOL Moderator

Hello Olaf Schipper

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