[kaka0331]

Hi everyone:

I want to use the Non Newtonian Model, so i create a new material.When i choose the Otswald de Waele model,i can not find the "consistency index" but only "Viscosity Consistency".In the Otswald de Waele model,the unit of "consistency index" is pas,but in cfx the
unit of "Viscosity Consistency" is pas.I want to know why there is no "consistency index" in the Otswald de Waele model in CFX.I'm sorry my English is poor,do i describe my problem clearly ?

[ghorrocks]

Is the parameter you are looking for the "Power Law Index"?

[kaka0331]

Thank you for your reply.This picture is from a paper,it is about one sort of Non Newtonian fluid.The paramete "k" in the table is what i'm looking for,we call it "consistency coefficient",the equation of Otswald de Waele is =k, is
viscosity,k is the consistency coefficient, is the shear rate,n is the power-law index,i'm looking for the "k" which we call it "consistency coefficient" in the Otswald de Waele model in CFX,but i can't find it.I think it is an important parameter can't be neglected in the model.

[Opaque]

The parameters of the model are documented as show in the image.

To use the formulation in ANSYS CFX, you must "re-dimensionalize" your values. The software expect the consistency to be given independently of the power law index; therefore, its dimensions cannot be a function of "n". That is where the "time constant" comes in.

If you set your parameters, say for TS = 5.4%, to

1. Time Constant = 1 [s]
2. Viscosity Consistency = 0.192 [ Pa s ]
3. Power Law Index = 0.562

It should work as you expect. What do you think ?

Hope the above helps,

[kaka0331]

Hi Opaque,i think you are right.I have looked up the Tutorials again ,the software indeed expect the consistency to be given independently of the power law index.I will do the simulation as you suggested,so thank you very much.