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The Hydraulic Jump: A Test Case for the SPH Model

Author(s): David Lopez Gomez

Linked Author(s): David López Gómez

Keywords: No Keywords

Abstract: Mathematical models applied to hydraulics have developed rapidly in the recent past with the implementation of Volume of Fluid (VOF) and GIS techniques - even though there are still areas in which physical model tests are required for accurate results. The new technique of Smooth Particle Hydrodynamics (SPH) opens a new landscape for mathematical processing which gives good results in the more extreme situations of flow in hydraulic structures where many new possibilities can be explored. SPH has shown good results in representing various coastal hydraulics phenomena but, will this type of mathematical processing also give good results in the more extreme situations of flow in hydraulic structures with high velocities. The hydraulic jump is a good test case because in this phenomenon turbulence plays a very important role and traditional models do not work. In this paper a study is described in which the SPH approach is used to solve a case consisting of a high tank, to give energy to the water, regulated by a gate which is assumed to have an instantaneous opening. The floor downstream is horizontal and flat without roughness. A wide crested weir is used to force the jump. The case is similar to that of Forster and Skrinde, 1950. For different jump shapes it was necessary to generate different upstream Froude numbers by adjusting the initial depth of water in the tank (H= 32, 18 and 10 m. ), and the level of the weir (1, 2, 3, 4, 5 m. ). The gate opening was in all cases fixed at one meter. The validation of the results generated hitches - because the SPH test case is not stationary, in spite of the fact that the test results are in agreement with the theoretical calculation. This encouraged us to construct a physical model in a test flume to check the SPH result. Comparing the video record with the SPH animation a wonderful agreement was observed, as much in velocity of propagation of the wave, as in the level of the water downstream of the jump. In conclusion, the SPH technique offers a powerful new tool for tackling hydraulics phenomena without physical model testing. At this time it is necessary to make an effort to develop this kind of model. In the near future this technological challenge will no longer be a problem.

DOI:

Year: 2007

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