Divide the surface of a cylinder with height of 8mm and radius 80mm into 8 equal parts(45 degrees)

Hi

I'm working on ERT, sensitivity, on COMSOL for multiphase(water and oil) flow

I have calculated the total current density of water and i need to calculate the total current density of oil(mix). Dividing the this image below into 8 equal parts would help me do that.

Please how do i divide this into 8 equal parts on COMSOL bearing in mind that this division has to be on the surface only.

THANKS IN ADVANCE.

Kind Regards