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The Angels are in the Details!

Computational Fluid Dynamics (CFD) Modeling to Predict Dangerous Rollers at Low Head Dams

Insights - 3D Modeling - Gannett Fleming
Author: Benjamin Israel-Devadason, PE, CFM, Senior Hydraulic and Hydrologic Engineer
The Danger at Low Head Dams

Low head dams, or run-of-the-river dams, present a deadly threat because of their ability to generate dangerous recirculating currents downstream, which can trap and drown victims, who are often unaware of the brutal power of the waters. Seasoned swimmers, including first responders and firefighters, have succumbed to death at these deadly structures. Hundreds of deaths have occurred at these dams across the U.S., including more than 50 in the past two years. Not far from Gannett Fleming’s headquarters in Harrisburg, Pennsylvania, the Dock Street Dam on the Susquehanna River has experienced 33 documented deaths.

Conventional Hydraulic Analysis

It is impossible to simulate, study, and remedy the highly dangerous and complex circulating currents at these low head dams using standard 1-D or 2-D modeling approaches. Even though generalized physical models and published empirical data are present to provide a general understanding of these currents, they don’t provide site-specific and flow-specific information regarding these dangerous hydraulic conditions. 

The Power of CFD Modeling

Recent advances in 3-D CFD modeling coupled with high performance computing clusters, offer a powerful approach to accurately simulate the transient “hydraulic rollers” that occur downstream of low head dams. An understanding of the hidden submerged forces and currents can be of immense help to engineers responsible for evaluating and mitigating the hazardous conditions at these dams. A powerful feature of CFD modeling is the visual output that can display complex hydraulic data in a manner easily understood by non-technical stakeholders, such as first responders, public officials, and the general public.

CFD Modeling, because of its ability to analyze and simulate hydrodynamics at a stunning level of detail, gives us night vision to see through the darkest of these hydraulic problems. The technology’s amazing accuracy to help predict and design solutions to remediate the deadly hydraulics can play a vital role in saving lives.

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