Discharge coefficient

The discharge coefficient is a determinative parameter in the prediction of forces on ships during levelling. This coefficient is not known a priori. Therefore one option is to perform a sensitivity analysis to check the influence of this parameter on the outcome of Lockfill calculations. A more preferable option is to check this number by scale model test or CFD calculations. The top right picture shows a PIV measurement of the velocity in a filling jet. The second picture at the right shows a CFD calculation of the (mean) velocity in a filling jet.

During the Smart Rivers Conference of PIANC in 2015 in Buenos Aires a paper has been presented by Deltares about the application of CFD to determine the discharge coeffient. To this end, a comparison has been made to a measurement of a scale model of a lock gate with gate openings. Various tests have been executed with accurate results. To allow a further validation of CFD the measurements include the registration of velocities at eighty points downstream of the lock gate. CFD shows good agreement with these measurements although the dissipation of energy in the flow field downstream of the lock gate is found to be overestimated.

This paper can be downloaded from the download page.