Intensity setting in k-e turbulence model

aras · June 11, 2011, 20:30

hi,

I am using k-e model for a pipe with many small details in it. at the velocity inlet,I am using intensity and length scale as criteria. but when the solution converges and I am checking the fluent results, at the inlet the intensity is 70% despite my input as 15%.

How is that possible? shouldn't it pick my forced intensity at the inlet? if so, why the results at the inlet shows 70%?

thx

samsi · June 12, 2011, 05:20

I think Fluent calculates the turbulent intensity related to the input of the velocity in the reference value panel. I think the default value of the reference velocity is 1m/s. Try to adjust this value to your inlet velocity. Maybe this helps...

aras · June 13, 2011, 10:18

thx alot,

I checked it and you are right! it calculates based on reference velocity.

So the question is, which intensity the solution is based on? the one I am giving at the inlet or the one it calculates based on reference velocity?

June 11, 2011, 20:30	Intensity setting in k-e turbulence model	#1
aras New Member araz Join Date: May 2011 Location: Toronto, Canada Posts: 19 Rep Power: 14	hi, I am using k-e model for a pipe with many small details in it. at the velocity inlet,I am using intensity and length scale as criteria. but when the solution converges and I am checking the fluent results, at the inlet the intensity is 70% despite my input as 15%. How is that possible? shouldn't it pick my forced intensity at the inlet? if so, why the results at the inlet shows 70%? thx maphd likes this.

June 12, 2011, 05:20		#2
samsi New Member Join Date: Apr 2010 Posts: 13 Rep Power: 16	I think Fluent calculates the turbulent intensity related to the input of the velocity in the reference value panel. I think the default value of the reference velocity is 1m/s. Try to adjust this value to your inlet velocity. Maybe this helps... villager and maphd like this.

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June 13, 2011, 10:18		#3
aras New Member araz Join Date: May 2011 Location: Toronto, Canada Posts: 19 Rep Power: 14	thx alot, I checked it and you are right! it calculates based on reference velocity. So the question is, which intensity the solution is based on? the one I am giving at the inlet or the one it calculates based on reference velocity?