no velocity in HVAC duct branch

[studioa]

Hello Elemer gurus -

in my spare time I keep trying out Elmer to compare it with other CFD tools.
For educational purposes I analyze the flow into HVAC systems.
This case is pretty simple an HVAC duct with one main branch and a small one.
I use incompressible air with a Smagorinsky constant/coefficient of .2. Initial velocity of 15.
When I analyze the results in Paraview, the air in the small branch duct doesn't get any movement ... or very little ... (the area with a red circle)
This seems rather strange as I was expecting a lot of air movement in that area.
Since this is an educational project I can upload all the files for more experienced users if they are willing to take a look at.

Thanks for help!