Complementary Physical & Computational Modeling
• Sponsor: Grant County Public Utility District
• Objective: To conduct an integrated study of flow on a fish bypass at the Wanapum Dam on the Columbia River using laboratory models and numerical simulations. The simulations guided the design process of an ogee-crested fish bypass and provided insights for several variations in the geometry. The goal of the fish bypass is to increase survival of juvenile salmonids migrating downstream through the project.
Research Goals:
- Understand the free-surface flow on the Wanapum Dam fish bypass
- Analyze the two-phase flow downstream of the bypass to minimize total dissolved gas
- Understand the approach flow in the forebay to maximize fish collection efficiency
- Understand the egress flow in the tailrace to maximize survival
Laboratory Models
- IIHR conducted laboratory experiments on a 1:50 scale forebay model, a 1:52 scale tailrace model, and a 1:24 scale sectional model
- The study included measuring free-surface elevations, pressure, discharges, velocities, flow patterns, gate operations, and scour potential
- Researchers considered different headwater elevations and gate settings
- The experimental data was used to validate the computational model
Computational Model
- IIHR researchers used the commercial CFD code Fluent 6.1
- Structured/unstructured hybrid grids accommodated the complex geometry, including gate slots, flow control gates, and an aeration slot
- IIHR used the volume of fluid (VOF) approach to model the water/air interface
- After validation with experimental data, IIHR modelers used the computational model to analyze the flow field and supplement areas of limited experimental data
- CFD modeling guided the design process and provided insights for several variations in the geometry
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