Hydraulics: Modeling

Physical Modeling

The UWRL has been building and testing physical scale models since its commissioning in 1965. Researchers build geometrically scaled models and utilize essential scaling parameters to accurately simulate prototype flow conditions. With both a nearby reservoir and various pumping possibilities on campus, the UWRL can achieve flow rates that exceed 100 cfs (2,800l/s) and physical modeling footprints that exceed 6,000 square feet (550 square meters). The UWRL uses the latest construction materials and techniques and a wide variety of instrumentation and experimental methods to document studies and provide high quality quantitative information for clients and team partners. Furthermore, the UWRL is able to safely host visitors both in the laboratory and virtually.

With over 60,000 square feet (5,600 square meters) of indoor floor space and outdoor modeling areas, we can accommodate large model scales to study complex flow behaviors, better manage experimental uncertainties, and reduce the potential for size scaling effects.

All Hydraulic Projects

Physical Model Types Commonly Constructed at the UWRL

• spillways of all types
• energy dissipation/outlet
• diversion structures
• fish barriers/fish passage structures
• river channels
• pumping plants
• pipe simulations
• erosion/sedimentation studies
• miscellaneous scale models of other hydraulic appurtenances

Benefits of Physical Modeling

In addition to physically simulating complex flow conditions, physical models assist researchers in the following ways:

• Hands-on working simulations are invaluable to the design process for many engineering teams.
• Physical modeling is a trusted and reliable method that will produce accurate results when performed properly.
• Small changes in the physical model (using interchangeable features or temporary structures of wood, plastic, mortar, sandbags, etc.) can be made easily to immediately see the resulting hydraulic changes.
• Multiple flow rates can be tested on a single model configuration in a very short time. For example, a flood routing or flood hydrograph can often be simulated in less than an hour.
• Specific hydraulic problems are immediately apparent in an operating physical model including problems like vortices, separation zones, scour potential, poor energy dissipation characteristics, wall overtopping, flow instabilities, floating and submerged debris, aeration effects and/or wave action.
• The effects of tailwater or submergence on a hydraulic structure can be observed in a physical model by simply varying the height of water in the downstream channel.
• Three dimensional effects, aeration effects and multi-phase flows, highly turbulent regions, standing waves and superelevation conditions can be modeled at the UWRL.
• Physical models facilitate “team” engineering. Geotechnical, structural, and hydraulic engineers can get immediate feedback and make contributory suggestions to the design as they witness flowing water through the physical model.
• Physical models allow videos or photographs of the moving water under the modeled flow conditions to be compared with prototype conditions, providing a valuable tool for quality control
  
  

Numerical & Composite Modeling (Computational Fluid Dynamics)

Composite modeling combines the benefits of physical modeling with the flexibility of numerical modeling to create a valuable tool for engineers designing new hydraulic structures or improving existing ones. Numerical modeling can offer insight that a physical model alone cannot offer due to the many visualization and plotting tools built into commercial CFD solvers. A numerical model can determine data such as pressure, velocity, flow depth, and streamlines at any and all locations in the flow domain. The data can also be archived for later use and analysis. The UWRL has multiple faculty that specialize in computational fluid mechanics and different commercial 2D and 3D codes for pressurized and open channel flows for man-made structures and the natural environment.

Highlighted Projects

All Hydraulic Projects

Numerical Models Commonly Simulated at the UWRL

• spillways
• energy dissipators and outlets
• diversion structures
• fish barriers/fish passage structures
• river channels, inundation studies, dam failures
• pump intakes
• pipe simulations
• water quality and temperature models
• scour and erosion, and ice studies

Benefits of Numeric Modeling

• CFD and other numerical models are often more flexible than a physical model in changing the physical geometry and/or hydraulic conditions, allowing many configurations to be tested for comparison.
• Larger extents can often be modeled numerically and at field scale such as large sections of rivers or entire reservoirs.
• Using CFD coupled with a physical model can allow the physical model to be built larger by using CFD to predict inflow boundary conditions for the physical model. This allows the physical model to focus on a smaller region in the area of the model focus with a larger model.
• CFD can be used to test rating curves of spillways prior to being built, physically saving crest design iterations in the physical model and reducing the cost of the model study.
• With a CFD model, pressures and velocities can be taken at any location in the model and pressure or velocity contour plots can be created on any plane allowing the modeler to visualize flow patterns or pressures at any location in the model.
• CFD can also be used prior to the physical model as part of the design process by modeling a small portion of the hydraulic structure to look for possible problems before the physical model is constructed.
• CFD models are also built at full scale removing scaling effects that can be associated with physical models.