improving contaminant mixing models for water distribution pipe networks siri sahib s. khalsa...
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Improving Contaminant Mixing Models For Water Distribution Pipe NetworksImproving Contaminant Mixing Models For Water Distribution Pipe Networks
Siri Sahib S. KhalsaSiri Sahib S. KhalsaUniversity of VirginiaUniversity of Virginia
Charlottesville, VACharlottesville, [email protected]@virginia.edu
Clifford K. HoClifford K. HoSandia National LaboratoriesSandia National Laboratories
Albuquerque, NMAlbuquerque, [email protected]@sandia.gov
Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under Contract DE-AC04-94AL85000.
ProblemProblem Development of New Mixing ModelDevelopment of New Mixing Model
Objective: Predict concentrations resulting from two pipe flows intersecting at a junction
Objective and ApproachObjective and Approach
Implementation and Data TestingImplementation and Data Testing
Ongoing ResearchOngoing Research
ConclusionsConclusions
Mixing in a cross junction is incomplete and physically bounded by predictions of the complete-mixing and bulk-mixing models
Our new models have been implemented into EPANET, and results show significant improvement in contaminant transport predictions
Employ computational fluid dynamics software to study contaminant mixing in cross junctions, develop a new mixing model, and implement it into EPANET
Understanding and predicting solute transport through water distribution pipe networks are important to mitigate potential contamination events
Much of the water distribution industry relies on the Environmental Protection Agency’s water quality simulation software (EPANET)
However, EPANET incorrectly assumes contaminants mix instantaneously and completely in junctions, leading to potentially inaccurate transport predictions
Use laboratory data to test and improve our new mixing model
Flow SimulationFlow Simulation3-D simulations with computational fluid dynamics software reveal incomplete mixing within junctions, contrary to the assumption of the current mixing model
Equal Flow Rates Unequal Flow Rates
• Bulk fluid momentum is retained in the mixing process
• Our new mixing model honors bulk advective transport as a lower bound to the amount of mixing in a junction
• A mixing parameter is used to scale the results between the complete-mixing and bulk-mixing model predictions
Tracer Inlet
Clean Inlet
Tracer Inlet
Clean Inlet
The new mixing model was implemented into EPANET and used to predict contaminant concentrations at various sensor locations in laboratory pipe networks
3x3 Network: Tracer Inlet Flow Rate > Clean Inlet Flow RateNew Mixing Model Solution
Original EPANET Solution
Original EPANET Solution
New Mixing Model Solution
3x3 Network: Clean Inlet Flow Rate > Tracer Inlet Flow Rate
Predictions by EPANET implemented with the new mixing model agree with laboratory measurements when appropriate mixing parameters are used
Sensor
Sensor Concentrations in 3x3 Network
Sensor
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Sensor Concentrations in 3x3 NetworkClean Inlet Flow Rate > Tracer Inlet Flow Rate
Source: http://toxics.usgs.gov/highlights/gw_cessation.html
Analysis of mixing behavior in other pipe-junction configurations
U Junction Double-T Junction
Inverse modeling to calibrate combined mixing model to pipe-network data
Development of mixing parameter regressions as functions of different flow conditions
Working with the Environmental Protection Agency to implement and distribute our new models
ContaminatedWater
Clean Water
Validation of combined mixing model using both large-scale and laboratory pipe-network data
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