Numerical Investigation of Inclined Dense Jet Behavior in Shallow Waters: Effect of Depth Variation and Free Surface Displacement

Abstract

The effects of the free surface on the behavior of inclined dense jets in shallow ambient were investigated in detail. The hybrid turbulence model scale-adaptive simulation (SAS), coupled with the volume of fluid (VOF) multiphase model, was used to detect the complex interaction of the jet and the free surface as well as displacements of the free surface and induced waves. The simulation results had reasonable accuracy compared with experimental data for dilution, geometrical characteristics, and complex structures of the jet, except the trend of return point dilution, which the increase of Froude number results in fluctuations in it. Moreover, it was shown that the dilution and geometrical quantities have the same trend whether the Froude number increases in the constant depth, or the depth level decreases in the constant Froude number, except the return point dilution, which is more sensitive to depth than to Froude number variation. The generation of waves due to the impingement of the jet on the free surface leads to more detrainment, and causes the emergence of an area with low dilution value beneath the jet on the bed before the return point. In addition, analyzing the three-dimensional (3D) concentration contours demonstrated that in shallower depths, the so-called lateral plumes impact the bed over a wider area. Therefore, based on the effects of waves and lateral plumes, the so-called return plate seems to give a better understanding of the environmental impacts of the jet on the bed than does the traditional return point.