[90nash]

Oops! Sorry about that. Too bad it didn't work.

[itchy]

Hi Filippo,

I have never done any non-Newtonian simulations in OpenFoam. So I am not familar with nonNewtonianFoam (I do DNS,LES,combustion). At the moment you use SimpleFoam (steady solver). Then it should be possible to run your case with pimpleFoam (unsteady solver). Try it with pimpleFoam.

How to check "accuracy" or better "error of your method":
1. Compare your results with experimental data (validation)
2. Compare your results with an analytic solution or with a simulation of a commercial CFD-code like CFX,Fluent etc. (verification)

--------That is the only way you can do it!!!!

There are some "engineering procedure" for checking accuracy:
1. Make a grid independent study
2. check for mass continuity, momentum, wall shear stress, forces and so on
3. Look at your results. Are the results reasonable in an engineering point of view.

----I am engineer, but in my opinion this procedure is only for rough estimations and not a good way to check accuracy-------

Why do not use residuals for checking accuracy???
Residuals only tell you how good your linear system of equations were solved. It do not tell smth about the accuracy. For example you could solve a wrong equation, which not match your problem. Then your residuals could look fine but your results are wrong. With residuals you can see the convergence not the accuracy.

---- Your case is convergent!! Are the results accurate???-------

What you can do now
1. Solve a problem for that experimental data or an analytic solution exist (use unsteady solver) -> validate/verificate your solver
2. Solve your 2d T-shaped geometry. Do your results look reasonable in an engineering point of view?? To check this use quantities like velocityfield, shear rate etc.
3. Are there transient effect in the 2d T-shaped simulation? check this.

Pherhaps your results are in terms of accuracy already good. You have a good convergence, because your residuals are stable.

kind regards
Florian

[fs.chemech]

Thank you very much for your valuable help Florian!!

I will try what you suggested!

Cheers,

FS

[viraj20feb]

Hey,

I am still confused about the units of K and what the exponential 'n' is doing in it. Can you please shed some light on it?

Thanks

Originally Posted by fs.chemech

Florian, thank you very much for your answer!!

Regarding the units of "k", I understood your explanation! Thank you very much!

So, I'm using "orthogonal" and not "corrected" because my mesh is orthogonal. I saw (I don't remember where) that in these cases we can use this definition... Do you suggest me to change this?

By the complete case, you mean my mesh and all the other folders ("0", "constant" and "system")?

Cheers,

FS

[MatteoFabbri]

Hello everyone,

Can someone explain me if it’s necessary to divide the consistency index “K” by the density in the power law transport properties ?

I’m working with a tomato purée fluid which has a range of K between 0.1 and 100 Pa*s and a density =1035 kg/m^3

Thank you for the attention

[wyldckat]

Originally Posted by MatteoFabbri

Can someone explain me if it’s necessary to divide the consistency index “K” by the density in the power law transport properties ?

Quick answer: Depends on which solver you are using. A few examples regarding the usage of "constant/transportProperties" and viscosity settings:

1. https://openfoamwiki.net/index.php/F...ble_solvers.3F
2. https://cfd.direct/openfoam/user-gui...port-rheology/