A multiphase model for the hydrodynamics and total dissolved gas in tailraces

Politano, Marcela; Carrica, Pablo M.; Weber, Larry

doi:10.1016/j.ijmultiphaseflow.2009.06.009

Cited by 65 publications

(44 citation statements)

References 38 publications

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“…The volume of fluid (VOF) method has been used for the study of freesurface flow in short river channels (Ma et al 2002). However, applications for large water bodies are limited due to the computational requirements of VOF-based simulations (Politano et al 2009Fu et al 2010).…”

Section: Turbulent Free-surface Cfd Modelsmentioning

confidence: 99%

Model development in OpenFOAM to predict spillway jet regimes

Wang

Politano

Laughery

et al. 2015

Journal of Applied Water Engineering and Research

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Hydropower is the most important renewable energy source. Though hydropower provides abundant benefits, dams have also altered natural flow conditions affecting fish habitat. Elevated total dissolved gas (TDG) can result in gas bubble disease in affected fish. TDG production depends on the gas volume fraction and bubble depth in the tailrace, which are a function of spillway jet regimes. This paper presents a model developed in OpenFOAM to predict spillway jet regimes. The model utilizes the volume of fluid method to capture the dynamic free surface. A Large Eddy Simulation model, together with Detached Eddy Simulation, was used for turbulence closure. The model adequately reproduced jet regimes observed in a reduced-scale laboratory model. Differences in jet regimes predicted at reduced and prototype scales were observed. Results suggest that turbulence, not scaled in the laboratory model, plays an important role in the flow characteristics downstream of spillways.

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Section: Turbulent Free-surface Cfd Modelsmentioning

confidence: 99%

Model development in OpenFOAM to predict spillway jet regimes

Wang

Politano

Laughery

et al. 2015

Journal of Applied Water Engineering and Research

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“…An optimized regulation policy for Bala Reservoir is proposed based on the numerical results. Politano (2009), Urban et al (2008, and Fu et al (2010) have developed unsteady two-phase threedimensional models to calculate the TDG downstream evolution of spillways. The accuracy is satisfied in their simulations.…”

Section: Objectivementioning

confidence: 99%

Eco-environmentally friendly operational regulation: an effective strategy to diminish the TDG supersaturation of reservoirs

Feng

Liang

et al. 2014

Hydrol. Earth Syst. Sci.

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Abstract. The presence of elevated total dissolved gas (TDG) downstream of a spillway may result in an increased incidence of gas bubble disease in fish. Supersaturated TDG is transported and dissipated more slowly in reservoirs than in natural rivers because of a higher water depth and lower turbulence and thus endangers fish. This paper presents the operational regulations concerning the mitigation of the TDG supersaturation impact on fish in the Bala Reservoir on the Zumuzu River. The paper includes the joint operations of the upstream and downstream power stations. A laterally averaged two-dimensional model is employed to simulate the TDG transportation and dissipation in the Bala Reservoir in addition to the hydrodynamics and water temperature. According to a comparison of the simulation results of different operational scenarios, this paper suggests a regulation scheme. With respect to the upstream power station, the adoption of an interval-discharge pattern instead of a continuous-discharge pattern is recommended to minimize the negative effect on the reservoir caused by supersaturated TDG. With respect to the downstream power station, the adoption of a surface tunnel rather than a bottom tunnel is recommended as a release structure. This paper is a reference for the eco-environmentally friendly operation of large and deep reservoirs.

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“…When the water depth is greater than 1 m, air bubbles will permeate into water and sustain the hydrostatic and atmospheric pressures, which wül affect the DO saturation in water (Politano et al, 2009). (10614303) is the property of Water Environment Federation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission.…”

Section: Cheng and Chenmentioning

confidence: 99%

Numerical Simulation of Dissolved Oxygen Concentration in Water Flow over Stepped Spillways

Cheng

Chen

2013

Water Environment Research

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This study developed an improved Eulerian model for the simulation of an air-water flow field over stepped spillways. The improved drag model applied different drag coefficients for bubbles and for free surface flows or gas cavities. Void fraction and turbulence correction were used in determining the bubble drag coefficient. The calculated air entrainment and air-water velocity could be adapted using these parameters. With the improved drag model, the Eulerian simulations predicted the location of the inception point, the distributions of air void fraction, velocity distributions, and pressure distributions. The change in the dissolved oxygen (DO) concentration from upstream of the stepped spillways, to downstream, was simulated based on the improved computational fluid dynamics model and the transport equation for DO transferring. The numerical DO concentration coincided with the experimental results. Therefore, the improved CFD model and the numerical methods presented here can provide possible optimization tools for strong air entrainment flows.

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A multiphase model for the hydrodynamics and total dissolved gas in tailraces

Cited by 65 publications

References 38 publications

Model development in OpenFOAM to predict spillway jet regimes

Model development in OpenFOAM to predict spillway jet regimes

Eco-environmentally friendly operational regulation: an effective strategy to diminish the TDG supersaturation of reservoirs

Numerical Simulation of Dissolved Oxygen Concentration in Water Flow over Stepped Spillways

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