finding torque in 2D Axisymmetric geometry(
 

Hello Everybody,

I am trying to find out the torque acting on a rotating cyllinder.
I have trwo concentric cyllinders of different dia(outer cyllinder & inner cyllinder)
in between cyllinder.. fluid(multiphase) is there...my inner cyllender is rotating in a certain angular velocity...
in this way i am trying to figure out the torque acting on the inner cyllinder?
when I am doing it in 3D it shows some value.../*finding it as moment around revolving axis N/m*/

But as it is symmetry ...when i am consideriang it as 2D Axisymmetric case
the torque( the moment around the axis), is 0...

My question is when every parameters 4 simulations are same for both the cases why it is showing zero value in the second case????????:(