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May 14, 2014, 05:55 
parabolic velocity by groovy bc

#1 
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Ali reza
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hi
I am going to have parabolic velocity inlet and I have defined it in a pipe which it diameter is 4mm and flow is laminar and this is the definition of fully developed flow in a pipe u z = u max (1 −r2/R2) and this is my definition Code:
{ inlet { type groovyBC; refValue uniform (0 0 0); refGradient uniform (0 0 0); valueFraction uniform 1; value uniform (0 0 0); valueExpression "vector(Umax*(1(sqr(r)/sqr(0.004))),0,0)"; gradientExpression "vector(0,0,0)"; fractionExpression "1"; evaluateDuringConstruction 0; variables "r=sqrt(pow(pos().y,2)+pow(pos().z,2));Umax=0.07;"; timelines (); lookuptables (); } and the other problem is I have got this velocity profile instead of parabolic one. thanks guys 

May 14, 2014, 09:30 

#2  
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Bernhard Gschaider
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Quote:
What do you mean with "coordinate is changing"? Even if your mesh is moving r is OK. r is a basically a field of values: one for every face of the patch. So it calcs r for every face separately (was this your concern)?
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May 14, 2014, 12:10 

#3 
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Ali reza
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yes I got what you explained and thats helpful.thanks for your answer however do you have any idea about the wrong velocity pattern which I have got at inlet ?
it suppose to be parabolic but it is something else 

May 14, 2014, 12:43 

#4 
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Bernhard Gschaider
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What I don't understand about this diagram: what is the distance on the bottom? Because for instance if it is y or z then it should go from 0.004 to 0.004. If it is the 3 of the points it should go from 0 to 0.004.
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May 14, 2014, 13:10 

#5 
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Ali reza
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coordinates are (3 points of circle at velocity inlet)
(0.008,0,0.020) (0.008,0.004,0.024) (0.008,0,0.028) it means that radius=0.004 

May 14, 2014, 14:12 

#6  
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Bernhard Gschaider
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Quote:
Please check whether this is the case specify what "distance" in your diagram means. I will NOT answer anything that arrives in the next couple of hours to give you time to properly think it through
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May 15, 2014, 02:37 

#7 
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oh I got it you are right and I find the solution thanks a lot


May 15, 2014, 02:55 

#8 
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Ali reza
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thanks it seems that it was other user's problem too however thanks for your protect


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