Using CFX-4.2 user fortran,one can get the physical derivaties such as du/dx.But in the cylindral coordinate one get du/dr or 1/r*du/dr? The problem rises from that I want to add some source term witch include some derivaties in cylindral coordinate.Must I add the term 1/r explicity in the dirivaties?

You should include all the terms you need in the source term. Before that you should look into the manual howe the equations are written in cylindrical coordinates, then applying the source terms as you like.

S.