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July 8, 2009, 21:04 
How to calculate the curvature in UDF

#1 
New Member
Xinqiang Xu
Join Date: Mar 2009
Posts: 5
Rep Power: 9 
Hi,
I use VOF model to simulate the liquidvapor two phase flow. I want to get the interface curvature by udf, but I don't know how to write the equation (showed as attachment) in udf. If you know how to deal with this, could you give me some suggestion? Thanks Xinqiang 

January 4, 2013, 04:48 

#2 
New Member
Join Date: Aug 2011
Posts: 3
Rep Power: 7 
I have same problem too I want to implement disjoining pressure and I need surface curvature of each cell


January 24, 2013, 21:06 

#3 
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anonymous
Join Date: Jan 2011
Posts: 23
Rep Power: 7 
You could access the curvature by the following
 Use solve>set>expert option for keeping the temporary memory from being freed [yes]  Then Use SV_C_TMP_0 in the udf to access the value of curvature. ( This would give you the value of secondary phase curvature)  Not always safe as this is the temporary variable and you access the values being last stored in this variable. So check before using it. 

February 10, 2013, 20:39 

#4  
Senior Member
Ehsan Asgari
Join Date: Apr 2010
Posts: 301
Rep Power: 9 
Quote:
I suppose that there might be another way, Saving C_VOF(c,t) into C_UDSI and extracting gradient by C_UDSI_G Goodluck 

February 15, 2013, 06:17 

#5 
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anonymous
Join Date: Jan 2011
Posts: 23
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Volume fraction is discontinuous, therefore you would require to smoothen the volume fraction field before the calculation of gradient and curvature.


July 29, 2013, 14:32 

#6 
Member
Shashank
Join Date: Apr 2011
Posts: 70
Rep Power: 7 
Is there a way to calculate curvature apart from using the SV_C_TMP_0 macro? I'm sure there must be a way to calculate divergence of the unit normal vector to the liquidvapor interface.


January 22, 2016, 21:08 

#7 
New Member
cfd^2
Join Date: Mar 2013
Posts: 28
Rep Power: 5 
What is the real meaning of the macro SV_C_TMP_0? Does it directly access the interface curvature? I did not find details about this macro...


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