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Old   April 11, 2005, 13:45
Default Turbulence%+Dh
  #1
abel
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hello, I found in many tutorials of fluent6.0(like elbow tutorial), in specifying turbulence boundary conditions that turbulence is modeled with INTENSITY % and hydraulic diameter the values of I% (often 10%)do not correspond with the definition of I%=(Rdh)^(-1/8) (etablished in user guide, modelling turbulence). and what exactly the hydraulic diameter. thanks
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Old   April 11, 2005, 16:42
Default Re: Turbulence%+Dh
  #2
pUl|
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Ok, good question.

Turbulence intensity calculation procedure as outlined in the Fluent manual works well for internal duct flows. Usually for such flows, using 1 or 10 percent makes little difference as eventually, the value changes as the solution proceeds due to the viscous effects that result due to the presence of the wall.

This page provides a good explanation about the Hydraulic Diameter:

http://www.piping-toolbox.com/hydrau...er-18_458.html
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Old   April 12, 2005, 04:43
Default Re: Turbulence%+Dh
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abel
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ok PU1! how about the Reynolds number presented in the first part of the tutorial ( Re=50000)!! and the formula I%=f(Re)??

thanks for all
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Old   April 12, 2005, 18:19
Default Re: Turbulence%+Dh
  #4
pUl|
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I'm not sure what exactly you are referring to, but even for a pipe elbow case, using 1 OR 5 or even 10% Turbulence Intensity should not influence the results for the same reason as I have given earlier in this thread.
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