How to calculate the curvature in UDF
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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 
I have same problem too I want to implement disjoining pressure and I need surface curvature of each cell:confused:

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. 
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 
Volume fraction is discontinuous, therefore you would require to smoothen the volume fraction field before the calculation of gradient and curvature.

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.

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