Scholarship & Research
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Item Numerical simulation of rock ramp fishway for small-bodied Great Plains fishes(Montana State University - Bozeman, College of Engineering, 2023) Ufelle, Cindy Chidumebi; Chairperson, Graduate Committee: Kathryn PlymesserThe preservation and restoration of fish populations and their habitats have become significant aspects of environmental conservation efforts. Effectiveness of fish passage structures plays a crucial role in facilitating the successful migration of various fish species. This research focused on utilizing Computational Fluid Dynamics (CFD) models to assess the hydraulic conditions within a rock ramp fishway with varying slopes and flow rates for small-bodied Great Plains fishes. This work built upon a previous study conducted by Swarr (2018) to investigate the passage success rates of three small-bodied fish of the Great Plains of North America: Flathead Chub (Platygobio gracilis), Arkansas Darter (Etheostoma cragini), and Stonecat (Noturus flavus) within a full-scale laboratory rock ramp fishway. Using commercial software, Flow-3D Hydro, CFD models were developed to simulate and predict hydraulic parameters such as flow depths, velocities, and turbulence kinetic energies (TKEs) within the fishway. To validate the accuracy of the CFD models, predicted flow depths and velocities were compared with observed data for two slopes: 2% and 10%. The CFD model results indicated that increasing slopes and flow rates led to corresponding increases in the mean values of the studied parameters. The mean depth varied from 0.051 m on the 2% slope to 0.068 m on the 10% slope. The mean velocity increased from 0.272 m/s on the mildest slope to 1.003 m/s on the steepest slope. Additionally, the average TKE ranged from 0.003 J/kg on the 2% slope to 0.014 J/kg on the 10% slope. The study highlighted that higher velocity and TKE values at steeper slopes may have contributed to the poor upstream passage rate, particularly for weaker swimmer species, like the Arkansas Darter, at slopes greater than 4%, as observed in the physical model study. Findings demonstrated that the presence of rocks in the fishway created diverse flow conditions. Low-velocity zones observed behind rocks within the fishway may provide favorable conditions for successful fish ascent. This research showcases the capabilities of CFD in providing quantitative data for optimizing fish passage structure design and contributing to conservation efforts.Item Investigation of crack arrest fracture toughness of laboratory-manufactured polycrystalline ice(Montana State University - Bozeman, College of Engineering, 2021) Alcorn, Derek West; Chairperson, Graduate Committee: Edward E. AdamsApproximately 50% of ice mass loss from ice sheets is due to icebergs breaking off in a process called calving. Icebergs are created through the incremental growth of crevasses, which are large fractures in the ice. Crevasse propagation and iceberg calving predictions within ice sheet models conflict with direct observations of crevasse processes. Current ice sheet models assume that a crevasse will propagate until it reaches a depth where the stress intensity factor at the crack tip is less than that of crack initiation, however, this is likely an oversimplification as current models over estimate crevasse depth. A more robust model would also account for the crack arrest fracture toughness, a measure of how well a material can stop an already propagating crack. Here, we calculate crack arrest fracture toughness for samples of laboratory-manufactured polycrystalline ice. These samples were created using a radial freezing technique with a reproducible grain size distribution of 0.95 mm + or - 0.28 mm analyzed by cross-polarized light. Specimens were notched and brought to failure via a short-rod fracture toughness test at controlled temperatures and a constant displacement rate in a commercial mechanical testing apparatus with an environmental chamber. The presented data agrees with short-rod fracture toughness data collected from ice cores at the Filchner- Ronne Ice Shelf in Antarctica, demonstrating quasi-stable crack growth behavior. Results show the crack arrest fracture toughness of laboratory-manufactured polycrystalline ice is approximately 25 - 50% of fracture toughness. Using the crack arrest fracture toughness determined in this study would further increase modeled crevasse depth, indicating more analysis is required. Future studies can incorporate these data to more accurately determine crevasse penetration depth and improve iceberg calving predictions within ice sheet models.Item Applications of the Green-Ampt infiltration model to watersheds in Montana and Wyoming(Montana State University - Bozeman, College of Engineering, 1989) Van Mullem, Joseph AlphonseItem A computational model of two-phase, turbulent atmospheric boundary layers containing blowing snow(Montana State University - Bozeman, College of Engineering, 1991) Liston, Glen EddyItem A new aggregate gradation modulus(Montana State University - Bozeman, College of Engineering, 1990) Surdahl, Roger WardItem Control of air related problems for PVC and aluminum irrigation pipelines(Montana State University - Bozeman, College of Engineering, 1984) Kishel, JefferyItem Sequential optimization of multiple non-monetary objectives in the operation of multiple reservoir systems(Montana State University - Bozeman, College of Engineering, 1974) Rao, Gadepalli Venkata VisweswarItem The mechanical placement of orthopedic magnets within the human knee joint(Montana State University - Bozeman, College of Engineering, 1996) Barber, Deborah A.A mechanical analysis of an orthopedic knee implant is presented. The analysis is performed on an orthopedic knee implant that utilizes repelling magnets placed on the articulating surfaces of the tibia and the femur. The repelling magnets theoretically serve to decrease the contact force and friction within the knee joint. A three-dimensional mathematical model of the human knee joint is utilized to analyze the mechanical effects of the implants within the knee. The geometry of the surface and the effects of the ligaments are incorporated into the model. The model is evaluated at several flexion angles. The placement of the magnets within the knee joint is varied, and magnet strengths are proposed. The model is then solved for the contact forces at the knee joint with and without the implanted magnets. The decrease in contact force due to the presence of the magnets within the knee joint is evaluated. The initial implant design consisted of a total of four magnets on the femoral surface, two medial and two lateral, and two magnets on the tibial surface, one medial and one lateral. The initial design was evaluated and the conclusion was made that a more effective design could be proposed. An implant that utilized a series of three magnets on both the medial and lateral femoral surfaces repelling against a single magnet placed on both the medial and lateral aspects of the tibial plateau was analyzed. The final conclusion was made that the alternate design using six magnets on the femoral articulating surface and two on the tibial articulating surface is indicated to be the preferred mechanical placement for magnets within the human knee joint. A summary of results for the initially proposed implant design and the alternative design options are presented.Item A tentative method of estimating k and u for Janssen's bin pressure equations(Montana State University - Bozeman, College of Engineering, 1961) Steeves, Harry F.Item Use of mixture theory to represent a cohesive elastic-viscoplastic material(Montana State University - Bozeman, College of Engineering, 1997) Barber, Michael JamesThe analysis of material properties depends upon detailed information of the physical, geometric, and chemical properties of the materials. Relating these properties to a set of mathematical models is the principle objective of mechanics. Mixtures of materials made up of several constituents require special consideration since the constituent behavior must be reconciled with the overall behavior of the mixture. Mathematical models and their validity must be established to represent these materials. This thesis establishes a methodology whereby a logical sequence of considerations may be followed to represent complex mixtures adequately. Several existing theories of mechanics are assimilated into a cohesive theory to demonstrate the validity of the mathematical model used to represent mixtures. A structured development of the second law of thermodynamics is constructed to allow additional constraint equations which will restrict the form of new parameters. An example of a wood-snow mixture is used to show how the analysis is to be completed. Laboratory tests were run to use as a means of constructing the values of the new constitutive parameters. Proposed ways of including more constituents and spatial dimensions suggested.