# Validation of FLUENT

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 August 28, 2010, 00:45 Validation of FLUENT #1 New Member   Destry Marulitua Siagian Join Date: Jul 2010 Posts: 20 Rep Power: 8 Dear all... i just run some cases about fluid flow around cylindrical structure.. how can i know my result valid or not? how can i know this FLUENT valid? thank you so much... Gbu

August 28, 2010, 05:25
#2
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Quote:
 Originally Posted by Destry Dear all... i just run some cases about fluid flow around cylindrical structure.. how can i know my result valid or not? how can i know this FLUENT valid? thank you so much... Gbu
What type of flow? you may have analytical solution for certain types like laminar or inviscid

August 28, 2010, 05:36
#3
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Destry Marulitua Siagian
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Quote:
 Originally Posted by kingjewel1 What type of flow? you may have analytical solution for certain types like laminar or inviscid

i do analytical solution for inviscid flow...
but from simulation the velocity around the pipe = 0..
but in analytical solution the velocity around pipe = 2*U
U = inflow velocity....

i do the simulation based on FLUENT tutorial....

August 29, 2010, 02:18
#4
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Destry Marulitua Siagian
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Quote:
 Originally Posted by Destry i do analytical solution for inviscid flow... but from simulation the velocity around the pipe = 0.. but in analytical solution the velocity around pipe = 2*U U = inflow velocity.... i do the simulation based on FLUENT tutorial....

i also do an analytical solution for 1 case from FLUENT tutorial,,,
when i do comparing,,, the result also give a big difference...
especially on the pipe surface..
but when i do comparing above the pipe,,, it gives close result..
is it the limitation of this program?

thx all

 September 1, 2010, 04:21 #5 Senior Member     Svetlin Philipov Join Date: Mar 2009 Location: United Kingdom Posts: 176 Rep Power: 9 Give more information.... and beware of the fact that close to obstacles the velocity lim-s to zero....

September 1, 2010, 04:46
#6
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Destry Marulitua Siagian
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Quote:
 Originally Posted by Philipov Give more information.... and beware of the fact that close to obstacles the velocity lim-s to zero....
inlet velocity= 1 m/s
pipe position in middle of frame...
i also have problem in pressure
also gives a big error (when i comparing to analytical solution)
the analytic solution using superposition of uniform flow+doublet equation...

here i attach velocity contour produce by fluent for my case
Attached Images
 1.JPG (47.6 KB, 7 views)

 September 1, 2010, 05:06 #7 Senior Member     Svetlin Philipov Join Date: Mar 2009 Location: United Kingdom Posts: 176 Rep Power: 9 I do not see velocity problems.... check Re and see the flow pattern.... How did you calculate that velocity must be 2*U?!?!? and where it must be so (around where)?

September 1, 2010, 05:27
#8
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Destry Marulitua Siagian
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Quote:
 Originally Posted by Philipov I do not see velocity problems.... check Re and see the flow pattern.... How did you calculate that velocity must be 2*U?!?!? and where it must be so (around where)?
the velocity must be 2*U*sin (tetha) in pipe's surface
where tetha is the angle to the center of pipe....
i calculate them from the superposition of uniform flow+doublet flow...

here i attach the picture again with the angle
Attached Images
 1.JPG (47.9 KB, 5 views)

 September 1, 2010, 05:41 #9 Senior Member     Svetlin Philipov Join Date: Mar 2009 Location: United Kingdom Posts: 176 Rep Power: 9 On the picture you have resultant velocity ( velocity magnitude) and the formula you are looking for "x"... try to show only velocity on x-axis...

September 1, 2010, 05:47
#10
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Destry Marulitua Siagian
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Quote:
 Originally Posted by Destry the velocity must be 2*U*sin (tetha) in pipe's surface where tetha is the angle to the center of pipe.... i calculate them from the superposition of uniform flow+doublet flow... here i attach the picture again with the angle
i calculate the resultan also in analytical not only in x direction....

i also attach the equation here....
thx before
Attached Images
 2.JPG (50.3 KB, 5 views)

 September 1, 2010, 06:12 #11 Senior Member     Svetlin Philipov Join Date: Mar 2009 Location: United Kingdom Posts: 176 Rep Power: 9 I am not sure if you can use these equations for all Re range....

September 1, 2010, 06:18
#12
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Destry Marulitua Siagian
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Quote:
 Originally Posted by Philipov I am not sure if you can use these equations for all Re range....

mmmmm

oke,,,
i'll try for smaller Re....

thx for helping

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