Transport Phenomena at Intersections of Pressurized Pipe Systems

Romero-Gómez, Pedro; Choi, Christopher Y.; Waanders, Bart van Bloemen; McKenna, Sean Andrew

doi:10.1061/40941(247)155

Cited by 17 publications

(26 citation statements)

References 9 publications

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“…To validate the experimental results, S configuration results are first compared with results from previous cross junction mixing studies [8,9] showing that the obtained results are in line with referenced authors and logically bounded between the complete (upper boundary of mixing where concentrations at outlet pipes are the same) and bulk (lower boundary of mixing where instabilities and diffusion of fluid interfaces are ignored) mixing line [11], as shown in Figure 3. For clarity reasons, Figures 3 and 4 show the results for double-Tee junction distances 5.6D, 10D and 15D only while all the other results for longer distances are presented separately in Section 3.1.1.…”

Section: Resultssupporting

confidence: 64%

“…In this approach an additional 3D advection-diffusion equation is solved with the isothermal steady-state RANS/k-model. It has been shown in previous studies [9,13,23] that this approach gives relatively good agreement with the experimental results. The model is defined as:…”

Section: Passive Scalar Modelsupporting

confidence: 75%

“…It can also be observed in Figure 3 that it is possible to determine the EPANET-BAM mixing parameter s (used in c mixture = c bulk + s(c complete − c bulk ) [11]) for double Tee mixing modeling by observing the experimental results e.g., for inlet flow ratio R f equal to 1 and a Tee distance of 10D, a recommended value of mixing parameter s reads 0.88. Same as for results from previous research [8,9], it can be observed that for different inlet flow ratios R f , the recommended mixing parameter s changes, i.e., with increase in flow ratio, the value of s increases. While the relationship between distance and the degree of mixing is obvious, complete mixing is still not achieved with the junction distance of 15D.…”

Section: Resultssupporting

confidence: 58%

“…Even for a specific problem there is a range of feasible values of S ct when using RANS turbulent models [21,22]. For RANS turbulence models values of S ct for double-Tee junction with 2.5D distance have been reported in range between 0.001 and 0.01 and for 5D between 0.01 and 0.1 [23] while for a cross junction configuration, a S ct number of 0.135 yielded the best agreement with experimental results [9], showing uncertainty in turbulent Schmidt number determination as given by different authors. It was reported that the Schmidt number is significantly different for RANS and LES turbulence models and that for LES models its value is 0.7 [24].…”

Section: Numerical Modelingmentioning

confidence: 93%

“…The greatest deviation from complete mixing occurs when the Reynolds numbers are the same for all the inlet and outlet pipes [8]. A water-quality model in EPANET was improved with experimental and three-dimensional computational fluid dynamics (CFD) approach for cross junctions with different inlet and outlet flow scenarios [9]. In turbulent mixing at a cross junction, there is a considerable difference from complete mixing [10].…”

Section: Introductionmentioning

confidence: 99%

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Experimental and Numerical Investigation of Mixing Phenomena in Double-Tee Junctions

Grbčić

Kranjčević

Lučin

et al. 2019

Water

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This work investigates mixing phenomena in a pressurized pipe system with two sequential Tee junctions and experiments are conducted for a range of different inlet flow ratios, varying distances between Tee junctions and two pipe branching configurations. Additionally, obtained experimental results are compared with results from previous studies by different authors and are used to validate the numerical model using the open source computational fluid dynamics toolbox OpenFOAM. Two different numerical approaches are used—Passive scalar model and Multiphase model. It is found that both numerical models produce similar results and that they are both greatly dependent on the turbulent Schmidt number. After the calibration procedure, both models provided good results for all investigated flow ratios, double-Tee junction distances, and pipe branching configurations, therefore both numerical models can be applied for a wide range of pipe networks configurations, but passive scalar model is the viable choice due to its much higher computational efficiency. Obtained results also describe the relationship between the double-Tee distances and complete mixing occurrence.

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Section: Resultssupporting

confidence: 64%

Section: Passive Scalar Modelsupporting

confidence: 75%

Section: Resultssupporting

confidence: 58%

Section: Numerical Modelingmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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Experimental and Numerical Investigation of Mixing Phenomena in Double-Tee Junctions

Grbčić

Kranjčević

Lučin

et al. 2019

Water

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Mixing at Cross Junctions in Water Distribution Systems. II: Experimental Study

Austin

Waanders

McKenna

et al. 2008

J. Water Resour. Plann. Manage.

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The present experimental study focuses on the characterization of complex mixing phenomena at pipe intersections within pressurized water distribution networks. To examine the complete mixing assumption at a cross junction, a series of experiments were conducted in the turbulent regime ͑R Ͼ 10,000͒. The experimental setup consists of a cross junction with various sensors, pumps, and a data acquisition system to accurately measure solute concentration. Selected experimental results are compared to computational fluid dynamics ͑CFD͒ results. In addition, the water quality model associated with a standard water distribution network simulator ͑EPANET͒ was reevaluated based on CFD and experimental data. Corrections based on experimental results are incorporated into EPANET ͑AZRED 1.0͒ for use in a case study. The study concludes that the complete mixing assumption can potentially create considerable errors in water quality modeling. Further, severe errors are likely to occur in systems with many cross type junctions due to bifurcation of the incoming flows.

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Experimental Verification of Incomplete Solute Mixing in a Pressurized Pipe Network with Multiple Cross Junctions

2009

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Water quality models based on accurate mixing data at cross junctions are important for estimating concentrations of chemical species in municipal water distribution systems. Recent studies indicate that the instantaneous complete ͑thus "perfect"͒ mixing assumption potentially can result in an erroneous prediction of water quality. The present study examines the updated "incomplete" solute mixing model at cross junctions in a network having multiple cross junctions. The model performance in predicting solute transport was evaluated through a series of tracer experiments in a pressurized 5 ϫ 5 network with 9 cross junctions. The perfect mixing model consistently overestimated solute dilution at cross junctions and predicted evenly distributed solute concentration throughout the network. In contrast, the incomplete mixing model demonstrated uneven distribution patterns with a distinct solute plume, and the corresponding results were significantly more accurate than those based on the perfect mixing assumption. Average prediction errors in tracer concentrations were 15 and 66% using the updated and perfect mixing models, respectively, and the difference was statistically significant ͑P-value Ͻ0.001͒. Therefore, this study concludes that the incomplete mixing model can drastically improve the prediction of solute transport in pressurized pipe systems that have multiple cross junctions.

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Transport Phenomena at Intersections of Pressurized Pipe Systems

Cited by 17 publications

References 9 publications

Experimental and Numerical Investigation of Mixing Phenomena in Double-Tee Junctions

Experimental and Numerical Investigation of Mixing Phenomena in Double-Tee Junctions

Mixing at Cross Junctions in Water Distribution Systems. II: Experimental Study

Experimental Verification of Incomplete Solute Mixing in a Pressurized Pipe Network with Multiple Cross Junctions

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