Consider a rectangular open-channel with a width of b1. This channel joins another channel with a width of b2, where b1>b2 (e.g. b1=10 m and b2=5m). There is a transition section between these two rectangular sections.

The question is that, is it possible to design the transition section's geometry in such a way that the turbulent intensity in the second channel (with less width) be minimized or reduced? does transition section's geometry and topology affect the turbulence in the second channel much?