mesh
  radial trisection
  trisection blocks, 3
  transition radius, 6.5
  numz 1
   zblock 1 1. interval 1
  numr 3
   rblock 1 8.0 interval 4
   rblock 2 3.0 first size 0.05 last size 0.5
   rblock 3 4.0 first size 0.5 last size 0.05
  numa 1
   ablock 1 90. interval 12
 end
end
