Dear all,

I want to solve the heat equation in a cube - I managed to set a dirichlet boundary condition on the top and bottom of the cube, by defining the individual planes

left = Plane (Pnt(0,0,0), Vec(-1,0,0) )

right = Plane (Pnt(1,1,1), Vec( 1,0,0) )

front = Plane (Pnt(0,0,0), Vec(0,-1,0) )

back = Plane (Pnt(1,1,1), Vec(0, 1,0) )

bot = Plane (Pnt(0,0,0), Vec(0,0,-1) ).bc(‘bot’)

top = Plane (Pnt(1,1,1), Vec(0,0, 1) ).bc(‘top’)

cube = left * right * front * back * bot * top

However, what I really want is that the Dirichlet bc are only set on parts of the bottom and top plane - for example on two circles with center (0.5, 0.5) and radius 0.1 which lie in the bot and top plane. How can I do that ?

A related question is - if I want to solve the heat equation in a sphere and set two Dirichlet boundary conditions - again on two circles lying on the surface of the sphere. How do I do that ?

Thanks a lot

Marie-Therese