How to set bondary conditions on a geometry from stl file?


I’ve created a geometry from an stl file using the following code. How do I specify boundary conditions at specific locations on the geometry. My geometry is an ellipsoid shell and I wish to have different BCs on 5 circular patches on the surface of my geometry. I know the approximate locations of the centers (It is okay if I find elements near to it). Is there a way to do it in python script?

My code:
from ngsolve import *
from netgen.meshing import *
from netgen.csg import *
import netgen.stl as ngstl

geo2 = ngstl.LoadSTLGeometry(“…/data/biotac_shell.stl”)
mesh = geo2.GenerateMesh(maxh=1.0)