PNNL-13501 - Pacific Northwest National Laboratory

shown in Figure 1. Simulated results matched observed
data well: observed drop angle = 57-deg, simulated = 55deg;
observed downstream/drop depth = 0.094, simulated
downstream/drop depth = 0.088, observed brink/drop
depth=0.18, simulated brink/drop depth = 0.15.
Figure 1. Evolution through time of the numerical model’s
solution for a drop structure. Contours relate to velocity
magnitude.
A second, commercially available three-dimensional
hydrodynamic model, STAR-CD, was used to simulate
the larger scale flow field upstream and downstream of
the Bonneville Project. These flows were simulated in a
steady-state mode using a rigid lid approximation (nonfree
surface). These two assumptions simplify the
numerical complexity, allowing for greater grid mesh
detail. STAR-CD was applied to the forebay, intakes, and
tailwater of the Bonneville Dam Project.
The model was verified by simulating February 7, 2000,
field conditions. Inflow boundary conditions for the First
and Second Powerhouses and Spillway were set using
recorded Project operations. Bottom roughness was
estimated using a Manning’s n value of 0.020. Results
showing simulated water velocities downstream of the
Bonneville Project are shown in Figure 2.
Figure 2. Numerically generated contours of velocity
magnitude downstream of the Bonneville Project
128 FY 2000 Laboratory Directed Research and Development Annual Report
Model data was then compared to water velocity data
collected using an acoustic Doppler current profiler.
Water velocities were compared at three depths through
the water column. A graphical comparison of observed
versus modeled data is shown in Figure 3.
Figure 3. Close-up of velocity magnitude contours near the
second powerhouse. Arrows compare numerical and
observed data at various locations.
Simulating Fish Behavior
Steady-state hydrodynamic results from the STAR-CD
application to the Bonneville tailrace were used as input
to NWGrid, developed by Harold Trease of PNNL.
NWGrid is capable of simulating the evolution of
particles introduced into the flow field. In addition, these
particles can be assigned various statistical properties
representing fish behavior. This ongoing area of research
is only beginning hence behavioral properties were
appropriately simplistic for this project. For the purposes
of this project, the “fish” particles were given a simple
uniform normal random distribution (Figure 4).
Figure 4. “Fish” particles entering Unit 5 of the first
powerhouse. Foreground structure is a prototype surface
collector which isolates flow from two of the turbine bays.