ARTICLE | Using Computational Fluid Dynamics to Sustain Fish Migration

Water. Our most precious resource. As problem solvers, we’re challenged with designing waterway features that optimize the amount of water needed for effective and sustainable structures in the built environment.

The challenge is that man-made features such as dams and spillways impede migration and disrupt river connectivity. One way to improve fish passage around dams is building fish ladders into the feature; allowing fish to bypass these structures through a series of ascending pools and jumps. But how do we know if the fish are even going to know where it is or use it before it is built?

At Bergmann, an affiliate of Colliers Engineering & Design, our water resource engineers solve complex challenges like how to ensure successful fish passage in our dammed waterways where a focus on key parameters like velocity and shear stress are key to success. How do we create a structure that creates the least amount of stress on the fish, for the smallest ecological and project cost?

Today, we can employ equations, that have been developed over centuries by scientists, mathematicians, and engineers, to view the way water moves in three dimensions using Computational Fluid Dynamics (CFD), a digital application that employs a number of equations which help define fluid flow. CFD enables us to create models that accurately depict conditions that were in the past only viewed in physical models. These were mostly reserved for large scale projects because of the time and financial expense. CFD modeling enables our team to be agile and accommodating to changes while examining a structure’s performance without the cost of a physical model.

While one- and two-dimensional hydraulic models exist and are sufficient for most applications, they are more appropriate for defining waterways with culvert and bridge crossings; or extremely flat floodplains where water flow travels in more than one direction. Not lending them suitable to complex modeling for fish ladders.

By employing the use of CFD, we can achieve the precision of a scale model in a fraction of the time and cost. CFD modeled structures can be designed to function optimally because velocity and shear stress can be accurately calculated before we bend metal and pour concrete – meeting the needs of the fish, fitting in with our natural environment, and saving money.

Could your project be more effective with CFD modeling? Ask the experts at Bergmann.