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Old   July 24, 2013, 03:13
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I do a simulation of a fluid domain that contains three inlets and three outlets, in the three inlets I impose a identic velocity profile for three inlets but when I check in FLUENT at each inlet the rate flow I observe that there is a differences in the rate flow in three inlets against in outlets I have the same rate flow?!

is that there is an explanation please for this difference of rate flow at the inlets although the profile of the imposed speed is the same?

Thanks a lot
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Old   July 24, 2013, 11:28
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It probably has to do with the quality of your mesh. What value do you use to find the volume flow rate? For example, if it is an area averaged, then the area average volume flow rate is given by:

\frac{1}{A} \int qdA

Where q is the mass flow rate going into element of area dA. Thus the mas flow rates of all elements on the inlet is averaged out.

Now, the distribution of mesh on all your three inlet can be different and hence the area averaged value can be slightly different. What is the percentage difference?

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Old   July 24, 2013, 11:55
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How do you impose identical velocity profiles to each of the inlets?
Have you written 3 different UDFs or do you use local coordinate systems?
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Old   July 25, 2013, 03:26
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Thank you for your response,

oj.bulmer: I check in fluent Rapport-->Flux, in inlet 1 I have 0.55243, inlet 2: 0.53254 and inlet3 : 0.52458

flotus1: I imposed the profile velocity by one udf
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