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wall law modifications non-newtonian fluids

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Old   January 10, 2013, 10:14
Default wall law modifications non-newtonian fluids
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Hi all,

I have changed the standard wall function in the k-e turbulence model by UDF, but I need to confirm if it is correctly implemented and the unique way to do this is looking for the u+ profile. Someone can help me, how can I obtain u+ from Fluent? In UDF there is any pre-defined "variable" for wall shear stress or friction velocity?
I'm studying a non-Newtonian turbulent flow in a pipe. My main doubt is how Fluent treat the non-Newtonian properties (viscosity as a function of shear rate) with the turbulence. Please, if someone have any information (papers or another type of information) can help me.
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Old   February 23, 2014, 17:17
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I am struggling to model turbulent flow of polymer solutions (dilute, power law fluids).
I have tried CFX and also FLUENT by modifying the viscosity term but I am keep getting wring results,
The most important thing for me is get the correct pressure drop and velocity profile which are coming completely wrong,
Looks like you are dealing with the same sort of simulation so I would appreciate if you help me out on this,
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Old   February 25, 2014, 05:48
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In my case, I modified the viscosity as a function of shear rate and also the wall functions in Fluent using an UDF... The velocity profile is more similar with the experimental result with this modifications. In the pulp case as in the polymer cases the pressure drop is lower than the water pressure drop in the same conditions. By modifying the viscosity and the wall function I get lower pressure drop but not yet similar to the experimental result.
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