Robust Eco-Hydraulic 3D Modeling Tools for Rivers with Complex In-Stream Strcutures
In-stream features such as fish passages and large woods are widely used by Reclamation for improving river management through enhanced fish passage and habitat restoration. Design methods and guidelines are rare for predicting their effectiveness. It is also difficult to predict the physical response of channels to their placement. The risk and liability of these in-stream features are rarely evaluated quantitatively prior to project implementation. Computer models have the potential to address the above issues. However, a key bottleneck of applying existing 3D models such as U2ARNS is the need for 3D mesh generation. Mesh generation for complex geometries, such as in-stream structures, can easily fail. Even when meshing can be completed, the resulted low quality of the mesh often renders 3D solver unstable. Ideally, a mesh generation tool for in-stream structures should be automatic and error-free. Unfortunately, such tool does not exist.
This proposed research aims to develop a novel alternative method which may be implemented into the latest high-accuracy 3D model U2RANS. The end-product is a robust eco-hydraulic 3D modeling tool for rivers with complex in-stream features. It will answer the following research questions:
Need and Benefit
In-stream structures have been widely used by all Reclamation Regions for river restoration, river management, fish passage and fish barrier. Their use, however, have been challenged due to the lack of general design guidelines that address the risk, safety, and morphological impact. Their longevity and effectiveness are usually unknown. At present, the only viable option to address the above issues is to use computational modeling tools. Previous 2D modeling studies found that the in-stream features are almost impossible to be included by 2D models. 3D high-accuracy modeling tools are needed but they are rarely available and used in the past. The current Reclamation 3D model U2RANS is one of the few 3D tools available to serve the above needs; but the proposed new research is needed as discussed in the previous sections.
This research end-product is critically needed for many projects at Reclamation. It will make big-impact to the community. It will be beneficial and used by all Reclamation regions involved in fish passage projects, placement of in-stream structures for river maintenance and infrastructure protection, river restoration and/or rehabilitation. The PI has been involved in several projects in the MP and UC regions and they have to be delayed due to the current issues of U2RANS. These projects can move forward only with the functionality in the new version of U2RANS.
Specific benefits include the following:
1. Availability of an accurate and robust, IBM-based, 3D modeling tool U2RANS for the design and evaluation of in-stream structures.
2. Great saving of engineers' time in modeling by eliminating the time-consuming step of 3D mesh generation. The increased efficiency and easiness of model use help the promotion of wider adoption of this next-generation design tool.
3. Contribution to the development of the in-stream structure design guidelines.
4. Contribution to the forensic evaluation of failed or partially functional in-stream structures with the aim of prevent future failures
5. Contribution to assess the risk and liability of in-stream structure.
6. Manuals, tutorials, and example cases that demonstrate how to use the new modeling tool.
Contact the Principal Investigator for information about partners.
Bureau of Reclamation Review
The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.
An Eco-Hydraulic Numerical Model for Flows with Complex In-Stream Structures (final, PDF, 15.9GB)
By Yong Lai
Report completed on September 30, 2021