Part two of our 10-part Stantec R&D Fund 10th Anniversary Series takes us into the world of Dr. Fanbiao Lin and hydraulic engineering
Computational fluid dynamics. CFD for short. It’s the art and science—heavy on the science; there are mathematical algorithms involved—of using computers to simulate how fluids flow through engineering systems in three-dimensional (3D) space. For example, how water flows through different parts of a water or wastewater treatment plant, such as pump stations or reservoirs.
When treated sewage, known as effluent, flows out of a treatment plant, engineers must understand how it mixes into “ambient” water, like rivers and streams. Traditionally, engineers could only use one-dimensional tools or calculations done by hand to predict how effluent might behave in these mixing zones. Trouble is, rivers and streams are three-dimensional and too complex for such tools. A river’s small islands, varying widths and depths, and distorted flow distributions make it a challenge to predict mixing. And if engineers can’t accurately predict how effluent mixes with receiving water, they can’t assess if effluent discharges comply with regulatory requirements and if aquatic environments are properly protected.
Dr. Fangbiao Lin stands in front of a scale model of a pumping station currently being constructed in New Orleans
Enter Dr. Fangbiao Lin (Lynnwood, Washington). He holds a Ph.D. in Water Resources and Hydraulics, specializing in CFD, so he’s really into this stuff. And like any good researcher, he’s curious, always asking questions like, “What if we use CFD instead of one-dimensional tools to understand mixing zones of treatment plant effluent discharges?”
In 2012, Fangbiao received a Stantec R&D Fund grant (now called Greenlight) to explore this question on a couple of wastewater treatment plants in Ontario, Canada. The process involved CFD modeling, on-site monitoring, and even aerial photography to track a harmless dye to confirm the accuracy of the CFD models. Stantec’s new approach gave clients and the local regulatory agency an accurate picture of how effluent can be adequately blended into nearby streams.
On the left, an aerial photo of the Speed River in London, Ontario, shows how the Hespeler wastewater treatment plant’s effluent (made visible using a harmless dye) mixes with river water. This correlates with the CFD simulated model on the right. This shows that the model can help plant operators predict the level of treatment required when effluent flow from the plant increases in the coming decades.
As awareness of Fangbiao’s research grew, so did interest in applying CFD to other project types. In the past few years, he has
- Provided assessments for a paper and mulch factory in Saskatchewan
- Modeled mixing zones for a wastewater treatment plant in Colorado
- Modeled thermal plume from a Tennessee Valley Authority nuclear power plant
- Modeled diesel fume dispersions from a bus garage and train maintenance facility in Ontario
- Helped get Arizona’s Horse Mesa Pump-Storage Power Plant up and running after a 50-ton piece of concrete broke free and fell into the intake vane of Horse Mesa Dam
Fangbiao also played a key role in one of Stantec’s largest assignments, the New Orleans Permanent Canal Closures and Pumps Project (PCCP). The team used CFD modeling to design the pump wet wells and discharging piping, evaluate flow patterns upstream and downstream of bypass gate structure channels, and provide velocity and water depth for sizing riprap (rocks used to prevent shoreline erosion). The team even used CFD to model wind speeds under storm conditions inside the facility’s buildings. Combining CFD modeling—which uses ANSYS FLUENT software—with physical modeling and other traditional 1D and 2D hydraulic modeling enabled Stantec to develop designs with confidence.
In addition to water and wastewater facilities, Fangbiao has used CFD on a wide range of project types:
- Power plant hydraulics
- Bank erosion studies
- Transportation facility diesel fume tracking
- Tunnel drop shafts
- Building air quality
CFD offers many advantages over traditional physical modeling, including a shorter turn-around time, lower cost, and the ability to access models any time after a project is completed. “Design teams and clients may not understand the extent of what CFD modeling can achieve,” Fangbiao says. “The best way to educate teams is to involve them in the research and pilot studies that ultimately help their clients.”
About this article
Stantec is celebrating the 10th anniversary of our Research and Development (R&D) Fund—now called Greenlight. Through Greenlight, Stantec invests $2 million annually into our employees’ big ideas, with half the funds earmarked for scientific R&D initiatives. Greenlight is part of our Creativity & Innovation Program, which nurtures the efforts of our people to apply any idea that benefits us, our clients, or our communities, and enhances our reputation, competitive position, and ultimately our financial performance. In the coming months, we’ll be profiling 10 of our R&D grant recipients and their work, so check back often for more stories.
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