Numerical Modeling of Mixed Flows in Storm Water Systems: Critical Review of Literature

Bousso, Samba; Daynou, Mathurin; Fuamba, Musandji

doi:10.1061/(asce)hy.1943-7900.0000680

Cited by 49 publications

(46 citation statements)

References 54 publications

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“…Each model has its strengths and limitations (Bousso et al 2013). an elastic water hammer to the majority of the water columns while using a rigid water column analysis to a small portion near the air-water interface.…”

Section: R a F Tmentioning

confidence: 99%

Numerical modelling of pipelines with air pockets and air valves

et al. 2016

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This work considers the behaviour of air inside pipes when the air is expelled through air valves. Generally, the air shows isothermal behaviour. Nevertheless, when the transient is very fast, it shows adiabatic behaviour. In a real installation, an intermediate evolution between these two extreme conditions occurs. Thus, it is verified that the results vary significantly depending on the hypothesis adopted. To determine the pressure of the air pocket, the most unfavourable hypothesis (isothermal behaviour) is typically adopted.Nevertheless, from the perspective of the water hammer that takes place when the water column arrives at the air valve and abruptly closes, the most unfavourable hypothesis is the opposite (adiabatic behaviour). In this case, the residual velocity with which the water arrives at the air valve is higher, and, consequently, the water hammer generated is greater.

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Section: R a F Tmentioning

confidence: 99%

Numerical modelling of pipelines with air pockets and air valves

et al. 2016

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“…Normally, elastic models are solved by using the method of characteristics [18,19] and rigid models by using the numerical solutions of ordinary differential equations [3,11,17,20]. In pressurized systems, the air effect can be analyzed as a single-phase flow, where the absolute pressure of the air pocket is computed between two water columns [10,11,21]. Regarding the analysis of 2D and 3D CFD modeling of air-water interface in closed pipes, they are still unyielding in the application of pipeline draining because length and time scales are not appropriate.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Analysis of a Water Emptying Pipeline Using Different Air Valves

Coronado-Hernández

Fuertes-Miquel

Besharat

et al. 2017

Water

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Abstract:The emptying procedure is a common operation that engineers have to face in pipelines. This generates subatmospheric pressure caused by the expansion of air pockets, which can produce the collapse of the system depending on the conditions of the installation. To avoid this problem, engineers have to install air valves in pipelines. However, if air valves are not adequately designed, then the risk in pipelines continues. In this research, a mathematical model is developed to simulate an emptying process in pipelines that can be used for planning this type of operation. The one-dimensional proposed model analyzes the water phase propagation by a new rigid model and the air pockets effect using thermodynamic formulations. The proposed model is validated through measurements of the air pocket absolute pressure, the water velocity and the length of the emptying columns in an experimental facility. Results show that the proposed model can accurately predict the hydraulic characteristic variables.

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“…Numerical models (Cardle and Song 1988;Leon et al 2006;Politano et al 2007) have been developed to model this process. Bousso and Fuamba (2012) provide a review of modeling approaches. However, a relevant observation is that the strongest surges typically occur just as the tunnel becomes initially surcharged and the resulting maximum hydraulic grade line elevation associated with the event may be even greater later in the filling process when the total storage in a deep tunnel and associated shafts is closer to the storage capacity.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Pressure Transients Due to Trapped Air Compression in Rapidly Filling Combined Sewer Overflow Tunnels

Wright

Klaver²,

Vasconcelos

2016

JWMM

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Numerical modeling indicates that high pressures can be expected when trapped air at the end of a pipeline is compressed as it stops a moving water column. In particular, the model results show that larger pressures are to be expected when compressed air volumes are small. Laboratory experiments where a trapped air pocket is compressed by an advancing filling front also confirm that small air volumes lead to the highest pressure rises. However, the model formulation essentially treats the moving water column as a vertical front with a trapped volume of air in front of it, an assumption that cannot be expected to hold for large diameter stormwater tunnels. The authors have been involved in the numerical modeling of rapidly filling flows in CSO storage tunnel systems. The Two-component Pressure Approach can predict the location where air can become entrapped and the associated volume, but the model framework is a single phase flow simulation and the air is not explicitly modeled. This leads to conceptual errors in the modeling of flow processes once the air becomes entrapped. The numerical model was reformulated to allowed the inclusion of the trapped air volume in the simulation in a simplified fashion. Simulations with the modified model for a specific application suggest that there are two types of flow conditions that can lead to trapped air pockets that are subsequently compressed although future investigations may define additional conditions. The simulation results suggest that only modest pressure rises should be expected in the particular application investigated and the physical explanations for this outcome are described.

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Numerical Modeling of Mixed Flows in Storm Water Systems: Critical Review of Literature

Cited by 49 publications

References 54 publications

Numerical modelling of pipelines with air pockets and air valves

Numerical modelling of pipelines with air pockets and air valves

Experimental and Numerical Analysis of a Water Emptying Pipeline Using Different Air Valves

Assessment of Pressure Transients Due to Trapped Air Compression in Rapidly Filling Combined Sewer Overflow Tunnels

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