The velocity output from the 1p tracer example is halved on the top and bottom boundaries.

Bug report The velocity output from the 1p tracer example is halved on the top and bottom boundaries.

What happened / Problem description: This problem occurred when I ran the tracer problems. They are located in

dumux/examples/1ptracer

dumux/test/porousmediumflow/tracer/1ptracer

The velocity output using the vtk output module will result in a halved velocity on the top and bottom boundaries. The file name is tracer.pvd. This issue can be seen easily when setting a constant permeability throughout the domain.

What you expected to happen: When the problem has top and bottom Dirichlet boundary conditions for pressure and constant permeability, the velocity field should be constant in space.