Confusion about the viscosity "eta" in the tutorial rheoTool/of90/tutorials/rheoFoam/fluidDamper

[OP-ACE]

Hello, Pimenta,

Thank you very much for sharing such a powerful tool, rheoTool. I am currently studying rheoFam.
However, I am facing some difficulties understanding the "fluidDamper" example in rheoTool/of90/tutorials/rheoFoam.

I am confused about the "eta" in the file rheoTool/of90/tutorials/rheoFoam/fluidDamper/CarreauYasuda/system/controlDict.

const volScalarField& eta_ = mesh().lookupObject<volScalarField>("eta");

• Is this "eta" referring to the viscosity of the Carreau-Yasuda fluid (which is a nonlinear function of the shear strain rate)?
• In 1D case, the viscosity of the non-Newtonian fluid is easy to understand, but in this 2D example, I am at a loss.
• How is this "eta" calculated? Is it calculated by OpenFOAM or rheoTool?
• Where can I find the program that calculates "eta"?

Best regards,

Pengfei Guo