Plot a function of two variables in Paraview

I have generated the files attached with a PDE solver. The files contain the numerical solution (A) of a two-dimensional PDE, which I want to compare with an analytical function of two variables (B), say, f(x,y) = 1+x^2+y^2. How can I do this in Paraview? I tried the solution proposed here, but it is not clear.

May you please provide me a detailed procedure to do this ? Thanks
solution000000.vtu (671.3 KB)

solution.pvd (170 Bytes)


You data only contains f_24 data, which computation are you trying to do ?