Modeling of the Free-Surface Vortex-Driven Bubble Entrainment into Water

Abstract

The recently developed GENTOP (Generalized Two Phase Flow) concept, which is based on the multifield Euler‒Euler approach, was applied to model a free-surface vortex—a flow situation that is relevant for hydraulic intake. A new bubble entrainment model has been developed and implemented in the concept. In general, satisfactory agreement with the experimental data can be achieved. However, the gas entrainment can be significantly affected by several parameters or models used in the CFD (Computational Fluid Dynamics) simulation. The scale of curvature correction C s c a l e in the turbulence model, the coefficient in the entrainment model C e n t , and the assigned bubble size to be entrained have a significant influence on the gas entrainment rate. The gas entrainment increases with higher C s c a l e values, which can be attributed to the stronger rotation captured by the simulation. A smaller bubble size gives higher gas entrainment, while a larger bubble size leads to a smaller entrainment. The results also show that the gas entrainment can be controlled by adjusting the entrainment coefficient C e n t . Based on the modeling framework presented in this paper, further improvement of the physical modeling of the entrainment process should be done.

Enhanced Oxygen Volumetric Mass Transfer in a Geometrically Constrained Vortex

“…Three different parameters were measured at the inlet and outlet: Dissolved oxygen (4, PreSens PSt3 Sensor), pH (5, Endress & Hauser memosens orbisint CPS11D) and redox potential (6, Endress & Hauser memosens orbisint CPS12D). An inlet ball valve (7) and an outlet clamp (9) were installed to balance the mass flow rate to obtain different operating regimes. Upstream of the outlet clamp, a pressure sensor (8, Endress & Hauser Cerabar T PMC131) was installed to verify the system outlet pressure.…”

“…For example, Duinmeijer et al [4] used three-dimensional stereo particle image velocimetry to measure the velocity field in the vicinity of the free surface and to investigate the validity of the analytic Burgers vortex model. Kimura et al [5], Cristofano et al [6], Putra and Lucas [7] investigated mass transport across the free surface of hydraulic intakes for several applications using numerical analysis and experimental setups. Invisible to the outside observer, there are intricate flow patterns beneath the surface, which only have been recently investigated [8].…”

An analogical model for the stationary black holes by the flow field of space-time fluid around a 3-dimensional point sink

“…The following forces are applied to a single spherical particle, with velocity v, in the inviscid flow field u [27][28][29][30][31][32]. By assuming the STF density to be equal to the particle density, ρ c , we have…”

CFD Study on the Influence of Liquid Viscosity on the Swirling Gas-Liquid Flow

“…Swirling flow is commonly found in nature and in various industrial applications, such as in static mixers and combustors, as well as in separation processes, such as in cyclones and inline swirl separators [1]- [7]. In inline separators and mixers, swirl elements are installed in the pipe to create swirling flow in the region downstream the swirl elements.…”