UDF in axi-symmetric case

manoj

I am solving 2d axi-symmetric problem. I am writing one udf for my case in which i want to know the local velocities. Now in rectangular coordiantes, the x and y velocities are denoted by C_U(c,t) and C_V(c,t). Then in axisymmetric case, how the axial and radial velocities will be defined in udf? Also I would like to know the velocity gradients of radial and axial velocities in x and y direction. (C_DUDX(c,t), C_DUDY(c,t), etc. in rectangular coordinates.). Thanking you in advance.