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-   -   How to calculate the curvature in UDF (http://www.cfd-online.com/Forums/fluent-udf/66199-how-calculate-curvature-udf.html)

Xinqiang July 8, 2009 21:04

How to calculate the curvature in UDF
 
1 Attachment(s)
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

Xinqiang

shiraz_man67 January 4, 2013 04:48

I have same problem too I want to implement disjoining pressure and I need surface curvature of each cell:confused:

vig January 24, 2013 21:06

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.

syavash February 10, 2013 20:39

Quote:

Originally Posted by vig (Post 403906)
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

vig February 15, 2013 06:17

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

shashank312 July 29, 2013 14:32

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.

cfd^2 January 22, 2016 21:08

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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