Contributed by Laurie Ebner, Hydraulic Engineer, U.S. Army Corps of Engineers’ Portland District
Laurie Ebner is a hydraulic engineer with the Portland District’s 14-person Hydraulic Design Section. A 15-year veteran of Portland District, Ebner specializes in using 3D numerical modeling to provide practical solutions to the water management issues facing the Corps of Engineers.
U.S. Army Corps of Engineers
For more than 130 years, the people of the U.S. Army Corps of Engineers’ Portland District have played an important role in the region. In the past, District engineers constructed coastal fortifications, cleared river channels and surveyed the frontier. Their future efforts focus on environmental resource management and protection.
Portland District encompasses nearly 97,000 square miles of land and water in Oregon and southwestern Washington. Their future is tied to balancing the region’s competing needs for navigation, flood control, hydropower, fish and wildlife habitat, disaster recovery, irrigation, and recreation.
Portland District operates navigation locks on the 465-mile-long Columbia-Snake Inland Waterway and maintains over 720 miles of federal navigation channels and harbors. With 22 multiple-purpose projects, Portland District produces 60 percent of the region’s hydropower.
Corps reservoirs supply irrigation for local farmers and supplement municipal and industrial water needs. But as progress claims more land, habitat for fish and wildlife suffers.
Helping Fish Pass Through Dams Safely
Perhaps the biggest challenge Portland District faces is helping fish pass through the dams safely. Since the 1950s, the Corps has spent more than $70 million researching ways to protect migratory fish in the Columbia-Snake River system. The District has built and funds eight fish hatcheries, and every aspect of upstream and downstream passage is being evaluated.
Tecplot 360 is used to visualize simulated flow through The Dalles Dam on the Columbia River. Using Computational Fluid Dynamics (CFD), Portland District engineers propose structural alternatives that impact flow patterns and help fish pass through dams more easily. Prototype J-Blocks on The Dalles Dam are being investigated as a possible way of steering fish away from the powerhouse’s turbines towards the fish gate.
Figure 2 is a map of the Portland District. The inset image shows The Dalles Dam. One of the goals of flow analysis is to determine the best way to help fish pass through the dam safely. Typically when the powerhouse is being used at 40% spill nearly 80% of fish will pass through the safer spillway.
CFD Modeling and Visualizing Results
With such a heavy emphasis on water resources, Portland District utilizes CFD modeling to enhance understanding of existing configurations as well as proposed operational and structural modifications. They use CFD models initially developed by Pacific Northwest National Laboratory (PNNL) and ENSR International (now AECOM), then make minor modifications to the models as needed (but primarily change project operations).
In order to plot and visualize their simulation results Ebner and Portland district turned to Tecplot, Inc. “We initially purchased Tecplot 360 because we needed to view 3D model results,” Ebner said. “In addition, our numerical datasets were growing larger and more complex. We needed a fairly robust software solution that could translate these large datasets into understandable information. Through the use of Tecplot 360’s advanced visualization techniques, we are able to communicate the results of our work more effectively to both other engineering disciplines within the Corps and our external customers — primarily the biological research community.”
Tecplot 360 is a Versatile Tool
According to Ebner, Tecplot 360’s versatility is its strong-suit. “I love the fact that Tecplot is not a single purpose software package,” she said. “It works tremendously well as a CFD post-processor, but it also works well with more basic 1D and 2D datasets. Furthermore, Tecplot is relatively inexpensive as compared to other CFD visualization tools, a very important consideration for an organization funded with taxpayer dollars.”
Ebner added that Tecplot, Inc.’s technical support group provides an intangible benefit. “Often times, software companies treat technical support as an after-thought. Tecplot, Inc. provides such excellent support, however, that I consider it one of the software’s greatest strengths,” she said.
The Dalles Dam Visualized in Tecplot 360
In this series of images, velocity vectors and contours show how the J-blocks cause the higher elevation flow to move more westward towards the fish gate.
- J-Blocks in The Dalles Dam with are shown in Figure 3. Velocity vectors and contours show how the higher elevation water flows almost straight through the powerhouse.
- The Dalles Dam with no J-Blocks, Figure 4, velocity iso-surfaces show how the flow velocity is nearly constant across the front of the powerhouse.
- The Dalles Dam with J-Blocks, Figure 5. velocity iso-surfaces show how the J-Blocks intercept the flow and create regions of low velocity. In theory these low velocity/strain regions will cause fish to swim higher and more westward towards the fish gates.
See also this blog: Simulating Fish Behavior to Protect Migratory Fish Runs »