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How to express strain rate in Comsol

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Old   December 9, 2014, 18:10
Default How to express strain rate in Comsol
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Hello everyone,

I am relatively new to simulation. I have a question in COMSOL but it is quite general. I am trying to define an analytic function in COMSOL. The equaiton is Carrea_Yasuda fluid model. It is non newtonian fluid model that is function of shear rate. How to write an expression for the shear rate for a 3D problem?

Thank you very much for your help.

Best regads,
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Old   December 10, 2014, 12:34
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Jeff Burnham
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Strain rate and shear rate are tensors, and that's how they're solved in 3-D. The lab data you fit to parameterize non-Newtonian models are usually from a testing apparatus that is essentially 1-D, so the tensor has a lot of zeros and can be represented as a single scalar value. That shouldn't stop you from being able to parameterize the fluid; you don't need to know the 3-D characteristics of the flow, you just need to know the lab data.

This is a FLOW-3D forum, not a Comsol forum, so you're not likely to get an answer here that's more detailed than that.
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