[Goldenballs]

Hi All,

I have never programmed in C before and thus am struggling with writing a user field function. I would like to write a function to determine spray penetration length. Something like:

"If (Volume fraction < X), return the max position in Z where this occurs"

I have so far:

(${LagrangianVolumeFractionPhase 1} < 0.75) ? max($${Position}[2])

However I get syntax errors and generally have no idea how to write it. Could anyone help me out?

Thank you.

[me3840]

You don't use field functions for this. Field functions make 1 value for each cell in the entire field, hence the term field function. You want to return just 1 value. That's a report.

You want to make a threshold of volume fraction < 0.75. Then make a maximum report on that threshold of position in Z. Run the report and you get your value.

[LuckyTran]

Originally Posted by me3840

You don't use field functions for this. Field functions make 1 value for each cell in the entire field, hence the term field function. You want to return just 1 value. That's a report.

You want to make a threshold of volume fraction < 0.75. Then make a maximum report on that threshold of position in Z. Run the report and you get your value.

I concur. Don't use a field function, unless you're trying to define a field.

[Goldenballs]

Originally Posted by me3840

You don't use field functions for this. Field functions make 1 value for each cell in the entire field, hence the term field function. You want to return just 1 value. That's a report.

You want to make a threshold of volume fraction < 0.75. Then make a maximum report on that threshold of position in Z. Run the report and you get your value.

Originally Posted by LuckyTran

I concur. Don't use a field function, unless you're trying to define a field.

Thank you both, threshold worked, all be it a bit crude.

I do have a couple of questions with regards to volume fraction, if you wouldn't mind?

I does the "volume" refer to the mesh cell size at that location? Other than the cell size, are there any key contributors to such a low (~0.0008) volume fraction, when I was expecting something in the order of 75%?

Thanks.

[me3840]

Volume does refer to the volume of the cell. There are only two components to the volume fraction - the volume and the phase. If your volume is an expected size then whatever is producing the phase is the problem.