Numerical Simulation of Air Entrainment on Stepped Spillways

Numerical and physical modelling approaches to the study of the hydraulic jump and its application in large-dam stilling basins

“…In addition, the code works with a number of different methods to model the free surface depending on the case, all of them derived from the Volume Of Fluid (VOF) as originally presented by Hirt and Nichols [88]. FLOW-3D ® has been widely used in hydraulic engineering applications, achieving successful results since its release [5], [89]- [92].…”

“…The second model tested was the RNG (renormalisation-group) − [103]. This model applies statistical methods to derivate the averaged equations for the turbulence quantities employed by the − model, showing a better ability to represent flows in complex geometries and with strong shear effects [89]. Finally, the − ω turbulence model, where ω is the specific dissipation rate of the turbulent kinetic energy, was employed [104].…”

“…According to the results presented, the RNG − was the turbulence model chosen for the research. This model has been widely used to simulate the turbulence properties [9] and, particularly, for hydraulic engineering applications [89], [106], [107]. Furthermore, for the simulation of hydraulic jumps, previous authors had already found a better performance of the RNG − turbulence model when compared to others [25].…”

“…This allows a continuous estimation of the rate at which air enters the flow. In these terms, the volume of entrained air rate ( ) is obtained as [89]:…”

“…In addition, is the free surface area for each cell. Moreover, for cases in which aeration constitutes an important feature, affecting the behaviour of the flow, such as the ones studied herein, it is of paramount importance to consider additional physical processes of the air transport in water [89]. To do so, FLOW-3D ® takes into account bulking and buoyancy effects by using the models presented hereafter [86].…”