Learning Forum

[sfaron]

Hi,

I am running multiphase simulations using the VoF method, with two phases. I enabled the surface tension force modeling and am using the Continuum Surface Force, without adhesion (no wall nor jump adhesion)

I am giving a constant surface tension to Fluent through the DEFINE_PROPERTY UDF (I could directly write the constant value in the GUI of Fluent but, because I ran some benchmark simulations where I changed the surface tension, it was easier to have the value directly in my UDF file rather than in the case file.

I would like to get, after running the simulation, the applied surface tension to work on the force balance between this force and other forces I apply with other UDFs. 

Is there a way to recover these values ? I can't find a way and I find it odd that a force that can be that important can't be recovered.

Thanks a lot for your help ! 

[Rob]

As surface tension is attached to the free surface maths which isn't technically available in all cells it may not be held in a documented storage macro. As such I can't comment further as I'm limited to documented functions. However... the fact that the definitions are held in the various header files is in the manual, and these are in the Ansys Fluent install under .../src means you may find something reading through those. 

[sfaron]

Hi Rob,

Thanks for your reply ! I tried to have a look in the header files and found two files where variables related to surface tension were mentioned, notably SV_BF_SURF_TENS in ./src/storage/storage.h, in the same list where SV_VOF_RG or SV_VOF_G are mentioned, which I also use in my UDF to get the VOF gradients after allocating storage.

As it is no documented variable, I was wondering if yet you could help regarding which thread contains the cell where the surface tension force is applied, in a two-phase multiphase flow problem ? As I tried to use this SV_BF_SURF_TENS variable but only got errors, such as "called object is not a function or function pointer" or SIGSEGV errors, after trying to allocate storage the same way I did for the VOF gradients, or using T_STORAGE_R_NV(t, SV_BF_SURF_TENS(pt))

Thanks a lot !