Learning Forum

[mohammadreza.kadivar]

I am writing a UDF to modify the Turbulent Prandtle number. It is a 3D problem and I need to have wall distance and wall shear stress to calculate yPlus and frcition velocity. How can I get these in the UDF?

[Rob]

Near wall cell distance should be covered in the documentation, if you need wall distance from cells not adjacent to a wall it's somewhat more difficult. Other properties will be covered in the various cell and facet list; they're all in the UDF manual or header files. 

[mohammadreza.kadivar]

I need it from cells not adjacent to a wall. 

also, what about the wall shear stress?

 

[Rob]

Then you are going to have a fun time figuring out how to find it: Fluent stores a cell position and you can find neighbours but they won't know about the wall that's not immediately adjacent. 

Have a look in here https://ansyshelp.ansys.com/public/account/secured?returnurl=/Views/Secured/corp/v251/en/flu_udf/flu_udf_DataAccessMacros.html%23flu_udf_FaceVariableMacros   

Note, Staff are unable to comment beyond what's in the manual for UDFs as they fall under specialist knowledge.