A Numerical and Experimental Study on the Characteristics of Hydraulic Jumps on Rough Beds

Deniz Velioglu, Nuray Denli Tokyay, Ali Ersin Dincer

Tuesday 30 june 2015

12:00 - 12:15h at Europe 1 & 2 (level 0)

Themes: (T) Water engineering, (ST) Hydraulic machinery and industrial flows

Parallel session: 5E. Engineering - Computational

Baffle blocks and sills are common accessory devices which are used in order to stabilize the location of a hydraulic jump and shorten the length of a stilling basin. On the other hand, strip roughness elements which cover the entire length of a basin may be an alternative. The objective of this study is to determine the effects of this type of roughness elements on the characteristics of hydraulic jumps such as conjugate depth ratio, jump length and energy dissipation. The study is carried out using experimental data and a computational fluid dynamics (CFD) model, namely Flow 3D. In the first phase of the study, the experimental data are compared with Flow 3D results in order to assess the sensitivity of the code. In the second phase, several investigations are made to determine whether strip roughness elements are effective on the characteristics of hydraulic jumps or not. The results show that strip roughness elements have positive effects on the characteristics of hydraulic jumps. The tail water depth reduction compared to classical jump is 18-20%. The length of the jump is reduced about by 20-25%. This type of roughness elements induce 2-3% more energy dissipation than that of a classical jump. Therefore, strip bed roughness elements may be considered as an alternative for baffle blocks and sills.