Volume 19, Numéro 2, Pages 141-157

Control Of The Hydraulic Jump By A Thin-crested Sill In A Rectangular Channel - New Experimental Considerations

Authors : Bachir Achour . Lyes Amara . Darshan Mehta .


The control of the hydraulic jump by a thin-crested sill was not studied from the theoretical point of view; experimental research only was able to investigate it quite appropriately, even though the tests undertaken in 1950 were quite restrictive. Although these tests are old, the conclusions of this research are still in effect today. The control of the hydraulic jump by a thin-crested sill is governed by three dimensionless parameters namely the incident Froude number F1, the relative position X/h2 of the sill, and the relative sill height S = s/h1. The 1950 tests involved only three values of the relative position of the threshold, that is X/h2 = 3; 5 and 10. This resulted in a diagram of three curves showing the variation in the relative sill height S as a function of the incident Froude number F1. If the point defined by the coordinates (S; F1) is located between two curves of the diagram, then it is necessary to carry out an interpolation that is quite binding. By designing and using an adequate hydraulic installation, the current study brings something new from an experimental point of view by involving a very wide range of the relative position X/h2 of the sill since 15 values of this parameter are considered. This quantitative supplement helped to generalize the problem for any flow condition. Even better, it allowed deriving an experimental equation enabling the explicit calculation of the position X of the sill, thus avoiding any interpolation operation. What is sought in general in the problem of controlling the hydraulic jump is to find the right value of the sill position X so that the hydraulic jump is formed completely on the stilling basin such that its length Lj is approximately equal to X. The present study responds perfectly and appropriately to this issue.


Control of hydraulic jump ; thin-crested sill ; sill height ; incident Froude number ; stilling basin