3D boundary with various segments
 

Hi All,
I am trying to model a cylinder inside a tank. The tank is obtained by extruding a rectangular plane. The cylinder is obtained by extruding (Cut material) a circle. However, along this cylindrical surface, I would like to have several layers to apply different boundary conditions. Does anyone know how this can be done? I tried extruding (cut material) circles at different z-directions but after extrusion, the surfaces just unite to become a uniform surface.

I also tried extrusion at different levels but with the add frozen option. The segments are obtained by using Boolean operation. However, the same thing still happens. The surface just joined up to be come a uniform cylindrical surface.

Can anyone help please??

Thank you so much.

Sincerely,
EH