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How to calculate the curvature in UDF

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Old   July 8, 2009, 21:04
Default How to calculate the curvature in UDF
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Xinqiang Xu
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Hi,

I use VOF model to simulate the liquid-vapor 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

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Old   January 4, 2013, 04:48
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I have same problem too I want to implement disjoining pressure and I need surface curvature of each cell
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Old   January 24, 2013, 21:06
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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.
weloveUDF and wond like this.
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Old   February 10, 2013, 20:39
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Quote:
Originally Posted by vig View Post
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.
Hi,

I suppose that there might be another way,
Saving C_VOF(c,t) into C_UDSI and extracting gradient by C_UDSI_G
Goodluck
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Old   February 15, 2013, 06:17
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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.
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Old   July 29, 2013, 14:32
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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 liquid-vapor interface.
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