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Rotation, Rheological model

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I am trying to simulate fluid flow in a pipe but I have two problems. I appreciate if anybody give me some hint:

1. I just see three rheological models available in COMSOL: Newtonian, Carreau, and Power law. So how is it possible to simulate another rheological models such as Herschel_ Bulkley, etc?

2. I dont see an option in COMSOL( although it is in the help) to simulation rotation of a pipe. In the options for wall boundary conditions, there is no such capability.

Thanks,

1 Reply Last Post 25.05.2011, 08:02 GMT-4

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Posted: 1 decade ago 25.05.2011, 08:02 GMT-4
Hi,
Herschel_ Bulkley is a rheological model with a yield stress. Below the yield stress the material behaves like a solid and above the yield stress the material behaves like a fluid. So you have a stress dependent phase transsition and the solid state (the relation between stress and strain) is not defined in Herschel_ Bulkley.
I guess, you have to build a workaround.

For modeling of rotating walls see the tutorial "dense suspension".

greetings
Uwe
Hi, Herschel_ Bulkley is a rheological model with a yield stress. Below the yield stress the material behaves like a solid and above the yield stress the material behaves like a fluid. So you have a stress dependent phase transsition and the solid state (the relation between stress and strain) is not defined in Herschel_ Bulkley. I guess, you have to build a workaround. For modeling of rotating walls see the tutorial "dense suspension". greetings Uwe

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