AF = π/4· DF2
mm = Lt/(Dt - Db)
cc = - Lt· Db/(Dt - Db)
D1 = (h - cc)/mm
A1 = π/4· D12
A2 = A1 - AF
w = CR· A2· [2· g· VF· (ρF - ρ)· ρ/(AF· (1 - (A2/A1)2))]1/2
q = w/ρ