Abstract
A series of laboratory tests was performed on the stability of organized horizontal vortices generated along the boundaries of bank vegetation, and the associated exchange of fluid momentum at the boundary of bank vegetation was measured by using a laser-Doppler velocimetry. The wavelength of the vortices is explained well by a linear stability analysis, suggesting that the vortices are generated by shear instability. At some value of width of main flow region without vegetation, the momentum exchange takes a peak value, where two vortex streets show a stable staggered array. A numerical computation employing SDS & 2DH turbulence model originally proposed by Nadaoka and Yagi was performed to calculate the 2D flow field, supporting the measurements.
