Numerical study of the turbulence characteristics of a submerged hydraulic jump

Vimaldoss Jesudhas, Vesselina Roussinova, Ram Balachandar, Ron Barron

Thursday 2 july 2015

16:45 - 17:00h at South America (level 0)

Themes: (T) Water engineering, (ST) River and coastal engineering

Parallel session: 13C. Engineering - Industrial

Hydraulic jumps are used extensively in hydraulic engineering as energy dissipaters below hydraulic structures. The transition from supercritical to subcritical flow in a hydraulic jump is characterised by large-scale turbulence and air entrainment. Over the years, numerous experimental studies have been conducted on hydraulic jumps. These studies have resulted in the development of several empirical formulae that are used in the design of hydraulic structures. However, the micro-structure of the hydraulic jump i.e., turbulence parameters, free surface fluctuations, coherent structures etc., are not fully understood. This is due to the fact that the conventional measuring devices such as the LDV and PIV have their shortcomings when used in bubbly two-phase flows. Most of the numerical studies of the hydraulic jumps have been two-dimensional and have failed to capture the three-dimensional nature of flow close to the sluice gate. In the present paper, three-dimensional, unsteady, Detached Eddy Simulation (DES) of a submerged hydraulic jump with an inlet Froude number of 8.2 is performed. Volume of Fluid (VOF) method is used for free surface tracking along with High Resolution Interface Capturing (HRIC). The results of the simulation is compared with existing experimental data. The three dimensional nature of flow close to the sluice gate captured by the present simulation is clearly depicted. Turbulence parameters along with the free-surface fluctuations are also reported. Proper Orthogonal Decomposition (POD) analysis of the velocity field was carried out to identify the most energetic coherent structures present in the flow. The details of this POD analysis are presented with relevant discussions.