Measurements were made in a smooth rectangular channel to establish the effect of the side walls of the channel on velocity distribution and resistance to flow. The velocity distribution in the central region of a section normal to the channel followed the log arithmetic law. In the vicinity of each wall, at a point in the vertical which varied with distance from the wall, the slope of the vertical velocity curve reversed. The velocity distribution over the entire section has been defined in dimensionless terms. As well, the width-depth ratio for the wall region is expressed as a function of a similar ratio for the channel.
The variation of a resistance coefficient computed from the measurements is shown to be a function of the flow Reynolds number. The resistance coefficient, for the same Reynolds number, is slightly greater than for smooth pipe or a smooth channel of infinite width.
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Resistance coefficients and velocity distribution smooth rectangular channel