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ruzfactor November 29, 2010 19:46

Hydraulic Diameter
I'm trying to solve a sudden expansion mesh in FLUENT using K-e model. I'm using turbulent intensity and hydraulic diameter for giving turbulence BC. I want to what should be the hydraulic diameter for a axisymmetric sudden expansion and also how do I guess the value of turbulence intensity?

pete November 30, 2010 04:10

CFD-Wiki contains an estimation of the turbulence intensity in a fully developed pipe flow. see That page also links to the definition of the hydraulic diameter.

ruzfactor November 30, 2010 07:49

For a sudden expansion there are two diameters. which one should be taken into account when I'm interested only the flow behaviour at the downstream of the expansion.

can you please help me setting the BC for a sudden expansion?? I really need some help here.

pete November 30, 2010 07:53

What you want to compute are boundary conditions at the inlet, right? Then it is the inlet dimensions that you should use.

ruzfactor November 30, 2010 08:13

yes. BC at inlet.

siri November 30, 2010 08:15

so simple!

n eureka ! i just discovered that .. any response < 10 characters won't get submitted to the forum.

P.S: was it to stop spam ?

ruzfactor November 30, 2010 08:46

2 Attachment(s)
I'm posting the pics of sudden expansion. The inlet dimensions were variable in the actual experiment but How do I do that in the given mesh? I have to compare the results with the experimental data.

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