Abstract:
The reported experimental study assesses the effects of flow non-uniformity on the momentum flux in straight compound channels. Two flumes were
used, featuring vertical and sloping banks. Starting with uniform flow condition, various imbalances in the upstream discharge distribution were
introduced. This resulted in a time-averaged lateral flow and advective transport of momentum, which interacted with the shear-layer turbulence
generated by the compound geometry. To investigate this interaction, the three contributions to transverse momentum flux (depth-averaged flow,
shear-layer turbulence and dispersive term of spanwise velocity) are assessed. The first two contributions were strengthened by the sloping banks,
while the third becomes important for the case of the vertical bank. With a lateral flow towards the main channel, the first contribution rises at the
expense of the second. With a lateral flow towards the floodplain, the first two contributions have the same order of magnitude, and the Boussinesq
approach is invalidated.
