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-   -   Power law fluid question (http://www.cfd-online.com/Forums/openfoam-solving/63305-power-law-fluid-question.html)

Wesley April 3, 2009 16:21

Power law fluid question
 
Please bear with me. I am a complete novice on fluid flow programs, and not nearly as familiar with rheology as I should be. I deal with food extrusion, and am trying to pull more science/engineering into my work. CFD is a potential way to reduce the number of iterations of die prototypes I would like to exploit.

I am using OpenFOAM 1.4 running in CAELinux. The fluid I am dealing with is a food extrusion melt. I am looking at the die and only the die. I have the rheology only a basic sense: I have k and n for the material as a power law fluid. I am working toward more useful measures, but this is what I have now. The non-Newtonian nature of the flow is very likely important to how the product will flow, so substituting an appearant viscosity for a given shear rate is not suitable.

The power law equation is of the form of: http://upload.wikimedia.org/math/3/3...4060f10ad7.png (thanks wikipedia)

I could use some guidance on how to use this information in OpenFoam so a very rough flow model could be run.

From what I have read, the correct solver to use is simpleFoam. The flow is laminar, so turbulence is and should be turned off.

Actually putting in the values for the fluid, in the form I have them, is where I run into problems.

Could somebody point me toward a tutorial, walk me through what needs to be plugged in where, or suggest what values should be measured on future rheology work that could be plugged into OpenFOAM?

Please keep in mind that I am using OpenFoam 1.4, so I am using the FoamX case manager. If I have to manually edit a file, I may need some more guidance.

Thank you in advance for any help you can give,

Wesley


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