UDF has to be compiled, can’t be interpolated   Steps   launch Fluent from the Command Line    For ansys 16.x, launch Fluent from the Command Line using the  VS2015 x86 x64 Cross Tools Command Prompt (not x64 x86 cross tools)     1)      Open the Start screen  (press Windows button  on your keyboard, Type ' VS2013 x86 x64 Cross Tools Command Prompt '   2)      Navigate to your working folder, i.e. the folder where your case and data files are (.cas & .dat).   3)      Type “fluent” in the command window to launch Fluent   or   “ C:\Program Files\ANSYS Inc\v161\fluent\ntbin\win64\ fluent.exe ”  (quotation signs included, in case of standard installation; fluent version: 16.1).   4)      Make sure that on the Environment tab  'Setup Compilation Environment for UDF'  is ticked. The default address is fine.     1.       Read mesh/cas file   2.     ...