YesThe Prandtl second kind of secondary current occurs in any narrow channel flow causing velocity dip in the flow
velocity distribution by introducing the anisotropic turbulence into the flow. Here, a study was conducted to explain
the occurrence of the secondary current in the outer region of flow velocity distribution using a universal expression.
Started from the basic Navier-Stokes equation, the velocity profile derivation was accomplished in a universal way
for both smooth and rough open channel flows. However, the outcome of the derived theoretical equation shows that
the smooth and rough bed flows give different boundary conditions due to the different formation of log law for
smooth and rough bed cases in the inner region of velocity distribution. Detailed comparison with a wide range of
different measurement results from literatures (from smooth, rough and field measured data) evidences the capability
of the proposed law to represent flow under all bed roughness conditions