TITLE:
Lateral Shear Layer and Its Velocity Distribution of Flow in Rectangular Open Channels
AUTHORS:
Xiaonan Tang
KEYWORDS:
Lateral Shear Layer, Velocity Distribution, Analytical Model, Lateral Width, Open Channel Flow, Secondary Flow
JOURNAL NAME:
Journal of Applied Mathematics and Physics,
Vol.7 No.4,
April
16,
2019
ABSTRACT: The lateral velocity distribution
of flow in the shear layer of open channel is required to many problems in river and eco-environment engineering, e.g.
distribution of pollutant dispersion, sediment transport and bank erosion, and aquatic habitat. It is
not well understood about how the velocity varies laterally in the wall
boundary layer. This paper gives an analytical solution of lateral velocity
distribution in a rectangular open channel based on the depth-averaged momentum
equation proposed by Shiono & Knight. The obtained lateral velocity
distributions in the wall shear layer are related to the two hydraulic
parameters of lateral eddy viscosity (λ)
and depth-averaged secondary flow (Γ) for given roughened channels. Preliminary
relationships between the above two parameters and the aspect ratio of channel, B/H, are obtained from two sets of
experimental data. The lateral width (δ)
of the shear layer was investigated and found to relate to the λ and the bed friction factor (f), as described by Equation (26). This study indicates that the lateral shear layer near the wall can be
very wide (δ/H = 14.6) for the extreme case (λ = 0.6 and f = 0.01).