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Old   June 17, 2007, 01:46
Default khalidb77@gmail.com
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Luis
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Hi I have a pipe flow I was consider the pipe as 2 D geometry I chose turbulence intensity and hydraulic diameter for turbulent specification method. I need now to estimate the value of hydraulic diameter in order I predict the value of turbulence intensity from it? Can anybody tell me how can I estimate it ?

Thanks in advance Luis

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Old   June 17, 2007, 02:13
Default About Estimating Hydrulic diameter
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khalidb77@gmail.com
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Also which of the turbulence specification methods being most accurate for pipe flow?

Thanks

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Old   June 17, 2007, 08:09
Default Re: About Estimating Hydrulic diameter
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Phil
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Hydraulic diameter is the diameter of the inlet. If you don't have a circular inlet you should estimate what the diameter would be if it were circular.

Turbulence intensity can be calculated from the diameter and Reynolds number. You should look up boundary conditions in the user guides for these equations and descriptions.

I always use intensity and hydraulic diameter but remember the turbulence intensity will change as soon as the fluid enters the model. So it may not matter!

Phil

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Old   June 17, 2007, 11:03
Default Re: About Estimating Hydrulic diameter
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LK
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thanks phil to the reply. My geometry actually is circular Which it a pipe but I draw it as 2 D ? so should i estimate new diameter for the inlet or I took the original diameter to the pipe?

Thanks

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Old   June 18, 2007, 01:34
Default Re: About Estimating Hydrulic diameter
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Wani
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If your geometry is circular, I recommend you to use axisymmetry simulation.
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Old   June 18, 2007, 01:44
Default Re: About Estimating Hydrulic diameter
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LK
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I cannot use axisymetric because i have water flow in the button of the pipe and air in top? What did you think there is ability to use axisymetric in problem like this?

REGARDS LK

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Old   June 18, 2007, 12:33
Default Re: About Estimating Hydrulic diameter
  #7
Fayyaz Hussain
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as a student of FLUENT i think axisymmetric is best but if you cant use axisymmetric due to geometric restrictions then it is better to do simulation in 3 D.

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Old   June 18, 2007, 15:33
Default Re: About Estimating Hydrulic diameter
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Phil
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If you have water in the bottom and air in the top it's a multiphase problem and you should be using a special model like the volume of fluid model.

I don't know of any reason why any dimensional configuration cannot be used with this sort of problem.

Phil
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Old   June 19, 2007, 01:17
Default Re: About Estimating Hydrulic diameter
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LK
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Phil I was already use VOF model but i need to know was axisymetric in my problem allowed or no? furthermore I am not mean there is no dimensional configuration cannot be use in my problem ? If you remember my first question is how much the value of hydrulic diameter should i enter into the inlet I mean how can I predict it?

Thanks LK

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