# Two-phase separator plane coordinate

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• Last Post 17 April 2019
eh3an posted this 15 April 2019

Hi

In a two-phase problem, I need an approximate coordinate (Normal vector, etc) of the separating plane of two phases per cell. To solve this problem, a multiphase VOF model has been used.

Is there any macro in the UDF environment to get the coordinates of the plane, or should the coordinates of this plane be estimated using the VOF gradient?

Thanks & Regards,

Ehsan

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abenhadj posted this 17 April 2019

Check if with the help with the gradient you can get the cells coordinates near the plane. Other approaches can not be explained in this community.

Best regards,

Amine

eh3an posted this 16 April 2019

In cells with vof between 0 ‌and 1 we got liquid and gas, there is a plane( sth like wall) that seperats liquid and gas in that cell (like PLIC approach in fluent), Whats the procedure in udf of Fluent to calculate the coordinate of that seprating plane.

abenhadj posted this 16 April 2019

I still do not understand the difference between separator plane and free-surface. The pictures you are inserting are from Fluent documentation that is why I will remove them. If you want to export the coordinates of the cells lying between 0 and 1 for VOF just make a cell loop, make an if statement and do whatever you like.

Best regards,

Amine

eh3an posted this 16 April 2019

In fact, I need the coordinates of the separator plane for two phases per every cell

And yes,I want to have that in UDF

Edit: Removed Fluent Documentation Pictures

abenhadj posted this 16 April 2019

Can you just insert instead of attaching the picture?

Do you mean you have a plane and from that plane you would like to now the coordinates of cells/faces where vof between zero and one? And you want to have that in UDF and not via export as already mentioned by my colleague?

Best regards,

Amine

eh3an posted this 16 April 2019

Not so. In all cells with vof between zero and one coordinates of this plane should be obtained

abenhadj posted this 16 April 2019

That means the isosurface of vof =0.5 Yes or no?

Best regards,

Amine

eh3an posted this 16 April 2019

No It is bubble rising problem. I need the coordinates of the planes that separate the bubble from the liquid. There is a method for this purpose, which can be used to determine the coordinates of this plane based on the vof gradient. Now, my question is, is there a udf that gives the coordinates of these planes without computing?

abenhadj posted this 16 April 2019

Is it a free Surface plane?

Best regards,

Amine

eh3an posted this 16 April 2019

Thank you for your reply. Can you explain more? I need these coordinates in the udf environment

kkanade posted this 16 April 2019

if you want coordinate, create isosurface with vof.

then you can export ascii file with file - export - solution data. it will write node and xyz coordinate.