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CFD Applications for Wastewater Engineering 1
Computational Fluid Dynamics (CFD) Applications for Wastewater Engineering
Laura Rozumalski Principal Engineer [email protected] Nick Jordan Water Resources & CFD Engineer [email protected]
October 18, 2018
freshwatereng.com
CFD Applications for Wastewater Engineering 2
About FreshWater Engineering
October 18, 2018
• Founded in 2014 by Laura Rozumalski • Woman-owned small business • Based in Madison
Hydrodynamic (CFD) Modeling Ecosystem Restoration
Water Resources Engineering Hydrographic Surveying
October 18, 2018 CFD Applications for Wastewater Engineering 3
Outline
• CFD modeling background • Capabilities of FLOW-3D • Applications of FLOW-3D to wastewater systems • FWE project example
• CFD modeling background • Capabilities of FLOW-3D • Applications of FLOW-3D to wastewater systems • FWE project example
CFD Applications for Wastewater Engineering 4 October 18, 2018
• Numerical analysis of Navier-Stokes equation to solve fluid flow problems
• Solves 2D/3D transient/unsteady flow problems • Modeler must weigh accuracy and efficiency • A powerful design and analysis tool
Applications
Computational Fluid Dynamics
• Aerodynamic design • Biomedical engineering • Metal casting • Hydraulic analysis & design • Environmental modeling • Municipal & wastewater systems
CFD Applications for Wastewater Engineering 5
Applications of CFD to Civil Engineering
October 18, 2018
• Municipal & Wastewater • Conveyance/wet tunnel hydraulics • Grit and sediment control • Flow control structures • Contact tanks • Clarifiers and settling tanks • Sewer design • Aeration dynamics
• Rivers • Hydraulic structures • Thermal discharge & contaminant modeling • Scour & sediment transport
• Dams • Spillways and stilling basins • Fish passage • Dam breaks
CFD Applications for Wastewater Engineering 6
Advantages of CFD
October 18, 2018
• Fewer assumptions and uncertainties than most engineering models
• Clearly view system geometry • Detailed understanding of flow • Excellent correlation to physical modeling • Less expensive than physical modeling • Realistic simulations
CFD Applications for Wastewater Engineering 7
Why use CFD to solve wastewater problems?
October 18, 2018
• Excellent design optimization tool • Assess performance of existing systems • Provide insight into complex interactions of hydraulic,
chemical, and physical processes • Gain understanding of system performance under different:
o Flow conditions o Operation scenarios o Design alternatives
CONFIDENCE
CFD Applications for Wastewater Engineering 8
FLOW-3D Capabilities
October 18, 2018
• Versatility • Geometry based on CAD designs • 27 physics packages
• Particle transport • Chemical reactions • Sludge settling • Moving objects
• Excellent visualization options
• Accuracy & Dependability • Industry-standard CFD model • Well validated • Free surface and pressurized flow
• Efficiency
October 18, 2018 CFD Applications for Wastewater Engineering 9
Outline • CFD modeling background • Capabilities of FLOW-3D • Applications of FLOW-3D to wastewater systems • FWE project example
CFD Applications for Wastewater Engineering 10 October 18, 2018
Circular Contact Tank Design Optimization
Poor mixing efficiency Not hydraulically efficient Poor performance
• Fully coupled hydraulic and chemical models
• Existing system analysis
CFD Applications for Wastewater Engineering 11 October 18, 2018
o Improved mixing efficiency o Even residence time
distribution o Hydraulically efficient Modeling Capabilities • Design optimization • Assess existing systems • Diagnose problems
Circular Contact Tank Design Optimization
Lowered center inlet Introduced center and outer
baffles
CFD Applications for Wastewater Engineering 12 October 18, 2018
Contact Tank Analysis
Coupled hydraulics, chemical, and micro-organism decay models
o Hydraulic performance o Mixing o Chemical/organism decay
• Design optimization • Assess existing systems • Simulate regulatory tests
(residence time, species concentration, etc.)
CFD Applications for Wastewater Engineering 13 October 18, 2018
Mixing Tank with Airfoil Impellers
Moving and rotating object simulations
Fluid/structure interactions
o Impeller design, type, rotational speed
o Mixing efficiency o Hydraulic performance • Design optimization • Evaluate current systems • Diagnose issues
CFD Applications for Wastewater Engineering 14 October 18, 2018
Secondary Clarifier Design
Customizable sludge settling velocity models
o Density currents o Hydraulic performance
• Design optimization • Evaluate existing systems
CFD Applications for Wastewater Engineering 15 October 18, 2018
Flux Splitting Grit Separator
Drift flux and sediment transport models: fluid/particle interactions
o Hydraulic balance and efficiency
o Sediment scour / buildup • Design optimization • Assess performance for
various flow conditions and sediment species
• Address operation and maintenance issues
CFD Applications for Wastewater Engineering 16 October 18, 2018
Complex Pipe System Analysis
Complex, time-varying, 3D flows
Air entrainment processes
o Fluid discharge o Hydrostatic and dynamic
pressures
• Optimize structure designs • Analyze current systems • Diagnose problems
CFD Applications for Wastewater Engineering 17 October 18, 2018
Municipal: Vortex Grit Chamber
Vortex modeling capabilities Fully coupled hydraulics and
particle transport models
o Multiple particle sizes
• Analyze suspended sediment removal efficiency
• Residence time analysis • Location-specific sediment
deposition rate
October 18, 2018 CFD Applications for Wastewater Engineering 18
Outline • CFD modeling background • Capabilities of FLOW-3D • Applications of FLOW-3D to wastewater systems • FWE project example
Inflow
Grit Chambers
CFD Applications for Wastewater Engineering 19 October 18, 2018
Project Example: Grit Chamber Optimization for DMWW
• Existing sedimentation problem in grit chambers • CFD resulted in a retrofit design to reorient gates
for even grit distribution
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Project Example: Grit Chamber Baffle Optimization for DMWW
• Existing sedimentation problem in grit chambers
• Design alternatives modeled to determine best gate orientation for improved grit distribution
• Flow conditions of 60-220 MGD • Simulated movement of 100-, 200-,
& 300-micron particles
CFD Applications for Wastewater Engineering October 18, 2018
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Project Example: Grit Chamber Baffle Optimization for DMWW
• Flow conditions of 60-220 MGD • Simulated movement of 100-, 200-,
& 300-micron particles
CFD Applications for Wastewater Engineering October 18, 2018
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Project Example: Infiltration Gallery Assessment
Y X
Z
20’x20’ Infiltration gallery
Modeling Domain Wave damping boundary
Wave propagation direction
N
• Proposed design for an infiltration gallery-type water intake in the Great Lakes
• Located in intermediate water depths
• Modeling investigated scour potential and flow characteristics of the preliminary design
• ‘1-year’ wave conditions simulated
October 18, 2018 CFD Applications for Wastewater Engineering
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Project Example: Infiltration Gallery Assessment
• Proposed design for an infiltration gallery-type water intake in the Great Lakes
• Located in intermediate water depths
• Modeling investigated scour potential and flow characteristics of the preliminary design
• ‘1-year’ wave conditions simulated
October 18, 2018 CFD Applications for Wastewater Engineering
CFD Applications for Wastewater Engineering 24 October 18, 2018
Is CFD the right choice?
Considerations • Project objectives • Budget and timeline • Regulatory requirements • Impact of modeling insights
CFD Applications for Wastewater Engineering 25 October 18, 2018
Thank you!
Questions? Contact Us! FreshWater Engineering freshwatereng.com [email protected]
Take-Away Messages
• CFD is a powerful tool that can provide insight to a wide array of wastewater & municipal projects
• Versatile, accurate, and efficient models have
enormous value that cannot be overstated