3D model and finding thermal analysis

Hello, i am trying to write a code that can show me the thermal (temperature) in an 3d model

i wrote the code and it worked for me but the problem is when i am changing the file to another file (another 3d model)

the code is not working anymore

so how can i write a code that if i eneterd importGeometry('file.stl') to any stl file the code will work all the time.

each stl file i need to import the code must work, the code that wrote just work for one stl file

by stl file I mean just one 3d model