Velocity in multicomponent flow (shan chen)

I have slightly modified example in showCases/multiComponent3d/rayleighTaylor3D.cpp to display velocity field in x, y and z direction by adding:

imageWriter.writeScaledPpm(createFileName("ux", iT, 6), *computeVelocityComponent(heavyFluid, slice, 0));

The resulting velocities seem to be correct only at the boundary between the two fluids. In the body of the fluids the velocities seem to be almost zero.

How can I get correct velocities in the bodies of the fluids?

Motivation: I would like to use non-Newtonian Carreau fluid together with Shan-Chen multicomponent scheme. The Carreau computes computeRhoBarJPiNeq. So I just want to be sure that I get correct PiNeq when using Shan-Chen with the non-Newtonian fluid.

EDIT: Or can you please confirm that Shan-Chen produces correct velocity fields in the fluid and it is just me that understands that wrongly?

I have found the following which answers my question: