On the Distribution of Velocity in a V-Shaped Channel


Department of Civil Engineering,Urmia University


Abstract. Several series of measurements were conducted to explore the hydraulic characteristics
of a V-shaped bottom channel by using low & high-speed velocity propellers for point-wise velocity
measurements. Also, in order to understand the e ect of cross sectional channel shape on the distribution
of depth-averaged velocity in the experimental channel, cases with di erent
ow rates were examined.
Using SURFER software, the contour plots of 2D isovels were drawn as interpolation among averaged
depths and velocities, obtained from superposing the various pro le sections. It was observed that isovels
are parallel to the channel boundary in a region close to the bed, and almost symmetric about the centerline,
with some deviations. The variation of point velocities in each slice considered along a spanwise direction,
in order to study the depthwise velocity pro le distributions, is shown. The lateral variations of depthaveraged
velocities indicate that the velocity distributions are almost symmetrical about the cross sectional
centerline, except for some
ow cases, in which there are slight deviations, despite the fact that the
condition was uniform for all cases. It was found that the widely used log-law for the vertical pro le of
velocity does not appropriately model the velocity distribution in this particular channel shape. Considering
the results obtained for the span- and depth-wise velocity distributions, especially the distortion of the
isovels and the location of maximum velocity, there are strong evidences of secondary currents that are
present in this channel cross section.