Piecewise constant function over a boundary

Hello,

I have a 2D axisymmetrc model and I'm trying to define an input pressure on the edge as a piecewise constant function of the r-coordinate.

Here's what I want to have for each segment: P=p_0exp(1iphase_j), for r_j < r < r_(j+1) where p_0, phase_j, r_j and r_(j+1) are input parameters.

I have tried several approches, but there is a jump in the input pressure at the segment boundaries after meshing. I'm wondering what is the best way to do this?

Thank you in advance for your help.