Effect of Tail Water Depth on Characteristics of Hydraulic Jump Formed Downstream of Stepped Weir.

In our work, experimental tests were conducted to study the hydraulic jump's characteristics forming in a flume with rectangular cross section. A broad crested weir with one step is used to produce a hydraulic jump downstream the flume. A 2D ANSYS-Fluent model version 20, which is a powerful tool used to simulate hydraulic problems with complex geometry, was used. Volume of fluid (VOF) method with a (k--ε) realizable turbulent model was applied to simulate the hydraulic jump for different flow conditions. After validating the numerical model with experimental data, it was then used to calculate sequent depths and velocity contours and to predict the location of the hydraulic jump formed in the flume. Different tail water depths were produced for different flowrate values by adjusting the opening of the tail gate located at the end of the channel. The water surface profiles obtained from the numerical model were in good agreement with those obtained using the physical model, as confirmed by a statistical analysis employing some standard error indexes. Thus, the numerical model can effectively estimate the hydraulic jump location. Results showed that the distance to hydraulic jump increases as the sequent depth decreases due to increasing tail gate opening. For most flow conditions, the depth of the tail water is slightly lower than the sequent depth. The relative height of the hydraulic jump located near the downstream was low and had shorter roller lengths than that located near the weir. Therefore, it is classified as undular jump. Some relations between studied variable are presented in the following section. [ABSTRACT FROM AUTHOR]