[Paraview] how to visualize a derived quantity in Paraview

[chandisasmal]

Hi Community,

I am using Paraview for the visualization of my OpenFoam data. I would 
like to visualize a derived quantity which is

(dUx / dx)^2 + (dUx / dy)^2 + (dUy / dx)^2 + (dUy / dy)^2

Can someone please help me how to do that in Paraview ?

Thanks in advance !

Cheers
Chandi