Marshall C. Richmond

Measurements of Turbulence at Two Tidal Energy Sites in Puget Sound, WA

Field measurements of turbulence are presented from two sites in Puget Sound, WA, that are proposed for electrical power generation using tidal current turbines. Time series data from multiple acoustic Doppler instruments are analyzed to obtain statistical measures of fluctuations in both the magnitude and direction of the tidal currents. The resulting turbulence intensities (i.e., the turbulent velocity fluctuations normalized by the deterministic tidal currents) are typically 10% at the hub heights (i.e., the relevant depth) of the proposed turbines. Length and time scales of the turbulence are also analyzed. Large-scale, anisotropic eddies dominate the turbulent kinetic energy (TKE) spectra, which may be the result of proximity to headlands at each site. At small scales, an isotropic turbulent cascade is observed and used to estimate the dissipation rate of TKE, which is shown to balance with shear production. Data quality and sampling parameters are discussed, with an emphasis on the removal of Doppler noise from turbulence statistics. The results are relevant to estimating the performance and fatigue of tidal turbines.

Survival Estimates for Juvenile Fish Subjected to a Laboratory-Generated Shear Environment

Abstract Juvenile rainbow trout Oncorhynchus mykiss and steelhead (anadromous rainbow trout), fall (age-0 and age-1) and spring Chinook salmon O. tshawytscha, and American shad Alosa sapidissima were exposed to shear environments in the laboratory to establish injury–mortality thresholds based on estimates of strain rate. Fish were exposed to a submerged jet having exit velocities of 0 to 21.3 m/s, providing estimated exposure strain rates up to 1,185/s. Turbulence intensity in the area of the jet where fish were subjected to shear was minimal, varying from 3% to 6% of the estimated exposure strain rate. Injuries and mortalities increased for all species of fish at strain rates greater than 495/s. American shad were the most susceptible to injury after being subjected headfirst to a shear environment, while steelhead and rainbow trout were the most resistant. There was no apparent size-related trend in susceptibility to high shear except that age-0 fall Chinook salmon were more resistant to shear environm...

Use of an autonomous sensor to evaluate the biological performance of the advanced turbine at Wanapum Dam

Hydropower is the largest renewable energy resource in the United States and the world. However, hydropower dams have adverse ecological impacts because migrating fish may be injured or killed when they pass through hydroturbines. In the Columbia and Snake River basins, dam operators and engineers are required to make those hydroelectric facilities more fish-friendly through changes in hydroturbine design and operation after fish population declines and the subsequent listing of several species of Pacific salmon under the Endangered Species Act of 1973. Public Utility District No. 2 of Grant County, Washington, requested authorization from the Federal Energy Regulatory Commission to replace the ten turbines at Wanapum Dam with advanced hydropower turbines designed to improve survival for fish passing through the turbines while improving operation efficiency and increasing power generation. As an additional measure to the primary metric of direct injury and mortality rates of juvenile Chinook salmon using ...

Six-Degree-of-Freedom Sensor Fish Design and Instrumentation

Fish passing through dams may be injured or killed despite advances in turbine design, project operations and other fish bypass systems. The six-degree-of-freedom (6DOF) Sensor Fish device is an autonomous sensor package that characterizes the physical conditions and physical stresses to which fish are exposed when they pass through complex hydraulic environments. It has been used to identify the locations and operations where conditions are severe enough to injure or kill fish. During the design process, a set of governing equations of motion for the Sensor Fish was derived and simulated to understand the design implications of instrument selection and placement within the body of the device. The Sensor Fish package includes three rotation sensors, three acceleration sensors, a pressure sensor, and a temperature sensor with a sampling frequency of 2,000 Hz. Its housing is constructed of clear polycarbonate plastic. It is 24.5 mm in diameter and 90 mm in length and weighs about 43 g, similar to the size and density of a yearling salmon smolt. The accuracy of the pressure sensor was determined to be within 0.2 psi. In laboratory acceptance tests, the relative errors of both the linear acceleration and angular velocity measurements were determined to be less than 5%. An exposure is defined as a significant event when the acceleration reaches predefined thresholds. Based on the different characteristic of acceleration and rotation velocities, the exposure event is categorized as either a collision between the Sensor Fish and a solid structure or shear caused by turbulence. Since its development in 2005, the 6DOF Sensor Fish has been deployed successfully at many major dams in the United States.

Quantifying turbulence for tidal power applications

Using newly collected data from a tidal power site in Puget Sound, WA, metrics for turbulence quantification are assessed and discussed. Of particular interest is the robustness of the “turbulent intensity,” defined as the ratio of velocity standard deviation to velocity mean. Simultaneously, the quality of raw ping Acoustic Doppler Current Profiler (ADCP) data for turbulence studies is evaluated against Acoustic Doppler Velocimeter (ADV) data at a point. Removal of Doppler noise from the raw ping data is shown to be a crucial step in turbulence quantification. Excluding periods of slack tide, the corrected turbulent intensity estimates at a height of 4.6 m above the seabed are 10% and 11% from the ADCP and ADV, respectively. Estimates of the turbulent dissipation rate are more variable, from 10-3 to 10-1 W/m3. An example analysis of coherent Turbulent Kinetic Energy (TKE) is presented.

Pore-Scale and Multiscale Numerical Simulation of Flow and Transport in a Laboratory-Scale Column

Pore-scale models are useful for studying relationships between fundamental processes and phenomena at larger (i.e., Darcy) scales. However, the size of domains that can be simulated with explicit pore-scale resolution is limited by computational and observational constraints. Direct numerical simulation of pore-scale flow and transport is typically performed on millimeter-scale volumes at which X-ray computed tomography (XCT), often used to characterize pore geometry, can achieve micrometer resolution. In contrast, laboratory experiments that measure continuum properties are typically performed on decimeter-scale columns. At this scale, XCT resolution is coarse (tens to hundreds of micrometers) and prohibits characterization of small pores and grains. We performed simulations of pore-scale processes over a decimeter-scale volume of natural porous media with a wide range of grain sizes, and compared to results of column experiments using the same sample. Simulations were conducted using high-performance codes executed on a supercomputer. Two approaches to XCT image segmentation were evaluated, a binary (pores and solids) segmentation and a ternary segmentation that resolved a third category (porous solids with pores smaller than the imaged resolution). We used a multiscale Stokes-Darcy simulation method to simulate the combination of Stokes flow in large open pores and Darcy-like flow in porous solid regions. Flow and transport simulations based on the binary segmentation were inconsistent with experimental observations because of overestimation of large connected pores. Simulations based on the ternary segmentation provided results that were consistent with experimental observations, demonstrating our ability to successfully model pore-scale flow over a column-scale domain.

Fish Individual-based Numerical Simulator (FINS): A particle-based model of juvenile salmonid movement and dissolved gas exposure history in the Columbia River Basin

This paper describes a numerical model of juvenile salmonid movements in the Columbia and Snake Rivers. The model, called the Fish Individual-based Numerical Simulator or FINS, employs a discrete, particle-based approach to simulate the movements and history of exposure to dissolved gases of individual fish. FINS is linked to a two-dimensional (vertically-averaged) hydrodynamic simulator that quantifies local water velocity, temperature, and dissolved gas levels as a function of river flow rates and dam operations. Simulated gas exposure histories can be input to biological mortality models to predict the effects of various river configurations on fish injury and mortality due to dissolved gas supersaturation. Therefore, FINS serves as a critical linkage between hydrodynamic models of the river system and models of biological effects. FINS model parameters were based on observations of individual fish movements collected using radiotelemetry methods during 1997 and 1998. A quasi-inverse approach was used to decouple fish swimming movements from advection with the local water velocity, allowing inference of time series of non-advective displacements of individual fish from the radiotelemetry data. Statistical analyzes of these displacements confirm that strong temporal correlation of fish swimming behavior persists in some cases over several hours. A correlated random-walk model was employed to simulate the observed behavior, and parameters of the model were estimated that lead to close correspondence between predictions and observations.

Laboratory Studies on the Effects of Shear on Fish

The overall objective of our studies was to specify an index describing the hydraulic force that fish experience when subjected to a shear environment. Fluid shear is a phenomenon that is important to fish. However, elevated levels of shear may result in strain rates that injure or kill fish. At hydroelectric generating facilities, concerns have been expressed that strain rates associated with passage through turbines, spillways, and fish bypass systems may adversely affect migrating fish. Development of fish friendly hydroelectric turbines requires knowledge of the physical forces (injury mechanisms) that impact entrained fish and the fishs tolerance to these forces. It requires up-front, pre-design specifications for the environmental conditions that occur within the turbine system, in other words, determining or assuming that those conditions known to injure fish will provide the descriptions of conditions that engineers must consider in the design of a turbine system. These biological specifications must be carefully and thoroughly documented throughout the design of a fish friendly turbine. To address the development of biological specifications, we designed and built a test facility where juvenile fish could be subjected to a range of shear environments and quantified their biological response.

Pore-scale and continuum simulations of solute transport micromodel benchmark experiments

Four sets of nonreactive solute transport experiments were conducted with micromodels. Each set consisted of three experiments with one variable, i.e., flow velocity, grain diameter, pore-aspect ratio, and flow-focusing heterogeneity. The data sets were offered to pore-scale modeling groups to test their numerical simulators. Each set consisted of two learning experiments, for which all results were made available, and one challenge experiment, for which only the experimental description and base input parameters were provided. The experimental results showed a nonlinear dependence of the transverse dispersion coefficient on the Peclet number, a negligible effect of the pore-aspect ratio on transverse mixing, and considerably enhanced mixing due to flow focusing. Five pore-scale models and one continuum-scale model were used to simulate the experiments. Of the pore-scale models, two used a pore-network (PN) method, two others are based on a lattice Boltzmann (LB) approach, and one used a computational fluid dynamics (CFD) technique. The learning experiments were used by the PN models to modify the standard perfect mixing approach in pore bodies into approaches to simulate the observed incomplete mixing. The LB and CFD models used the learning experiments to appropriately discretize the spatial grid representations. For the continuum modeling, the required dispersivity input values were estimated based on published nonlinear relations between transverse dispersion coefficients and Peclet number. Comparisons between experimental and numerical results for the four challenge experiments show that all pore-scale models were all able to satisfactorily simulate the experiments. The continuum model underestimated the required dispersivity values, resulting in reduced dispersion. The PN models were able to complete the simulations in a few minutes, whereas the direct models, which account for the micromodel geometry and underlying flow and transport physics, needed up to several days on supercomputers to resolve the more complex problems.

Injury and Mortality of Juvenile Salmon Entrained in a Submerged Jet Entering Still Water

Abstract Development of more eco-friendly hydroelectric facilities requires better understanding of the biological response of juvenile fish when they migrate through the turbines and other downstream passage facilities. Juvenile fall Chinook salmon Oncorhynchus tshawytscha were exposed to turbulent shear flows in a laboratory by using a fast-fish-to-slow-water mechanism in which test fish were carried by the fast-moving water of a submerged turbulent jet into the slow-moving water of a flume. Fish were released at six nozzle velocities: 6.1 (reference control), 12.2, 15.2, 18.3, 21.3, and 22.9 m/s. The onset of minor and major injuries occurred at 15.2 and 21.3 m/s, respectively. The acceleration magnitude threshold (m/s2) of major injury for the fast-fish-to-slow-water mechanism in this study was found to be significantly higher than that for a slow-fish-to-fast-water mechanism used in a previous study in which test fish were introduced into a turbulent jet from slow-moving water through an introduction...