Numerical computation of the flow in hydraulic jump stilling basins

Abstract

Abstract The formation of a hydraulic jump in a stilling basin downstream of a spillway with Froude number Fr = 6 and developed upstream flow was investigated using a physical and a numerical model. The numerical model is based on the 2D Reynolds-averaged Navier–Stokes equations, where the free surface is represented using a refined Volume-Of-Fluid (VOF) algorithm, the internal obstacles are described by means of the Fractional Area–Volume Obstacle Representation (FAVOR) method and the turbulence dynamics are represented using a specially developed RNG k–e closure model. Additional features of the code that are vital for its practical application include an automatic time step control, high–order schemes for advection and a variety of boundary conditions for the dependent variables on the free surface and adjacent to the internal obstacles.With this model, the hydraulic jump characteristics were analysed in two stages. First the turbulence model was not used, to describe the initial stages of jump formation and obtain suitable initial and boundary conditions. Then the full model was used to compute the time history of the dependent variables at selected locations and sections. The computed velocity, pressure values were compared with laboratory measurements and formulae available in the literature. The agreement between the numerical results and laboratory measurements was satisfactory. Keywords: FAVORfree surfacehydraulic jumpnumerical modelRNG k–estilling basinVOF