Reply To: No contour Variables for Velocity
The countours are not explicitly stored in the VTK file. Instead it contains the raw vector fields of e.g. the velocity in this case (really any functor) from which you can then compute and visualize contour lines in ParaView.
As the contour tool there expects a scalar field you will first have to apply some norm to the velocity field. Alternatively you can also use the results of e.g. OpenLB’s euklid norm functor.