Large eddy simulation of rough and smooth liquid plunging jet processes

Large eddy simulation based on the Smagorinsky dynamic sub-grid scale model in combination with the multiphase volume of fluid (VOF) model, was used to simulate the flow of two turbulent plunging water jets. The jets were intended to simulate a weakly disturbed jet with low turbulence content and a highly disturbed jet with a profile almost fully-developed at the exit Reynolds number of 9000. The simulation captured successfully the previous experimentally-observed topological phenomena taking place during the transient impact and continuous-entrainment regime. It showed that surface instabilities in the free jet, due to its turbulence content have remarkable effect on submerged interfacial area, air volume, and air-entrainment rate. The simulation predicted an air entrainment rate within the range of semi-empirical correlations. The calculated mean velocity field exhibited almost identical trends for both. The combination of the LES-VOF models achieved a reasonably good level of agreement with experimental and empirical results.