Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 21 for “"Boundary shear"”.
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Boundary Shear Stress Along Vegetated Streambanks
… examined the effects of riparian vegetation on boundary shear stress (BSS) by completing the following objectives: (1) evaluating the effects of streambank vegetation on near-bank velocity and turbulence; (2) determining a method for measuring BSS; and, (3) examining the effects of streambank …
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Boundary shear stresses in curved trapezoidal channels
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Sanitary Engineering, 1961.
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Grain-boundary shear in AA7050: an experimental investigation using digital image correlation and finite element techniques
… under standard tensile loading, and shear deformation along grain boundaries has been shown to be a key mechanism for deformation and failure of the material. Using experimental and simulation techniques, the behavior of hot-rolled and aged aluminum alloy 7050 is investigated under …
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A continental shelf bottom boundary layer model : the effects of waves, currents, and a movable bed
A simple model for the bottom boundary layer on the continental shelf is presented. The governing equations are developed for a stratified, turbulent Ekman layer in a combined wave and current flow over a moveable sediment bed. An eddy diffusivity closure scheme that includes the effect of …
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Flow, sediment transport, and bed topography in straight and curved gravel-bed channels
… the mechanism that accommodates for spatial boundary shear stress variations in curved gravel bed channels. The flume experiments involved detailed measurements of bed topography, velocity, and sediment transport in both a curved channel and straight channel with and without an upstream …
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Modelling of simple prismatic channels with varying roughness using the SKM and a study of flows in smooth non-prismatic channels with skewed floodplains
… distributions of depth-averaged velocity and boundary shear stress for both roughness types. Furthermore, the percentage shear force on the wall of a channel is accurately obtained for both roughness types and guidance is given as to the choice of the three calibration coefficients the model …
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The Effect of Wall Jet Flow on Local Scour Hole
… cases. The model predictions of velocity and shear stress were compared against experimental observations. The experimental data was used to develop new empirical relationships to describe the pattern of boundary shear stress caused by a wall jet over fixed beds and in equilibrium scour holes. …
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Exploration of incompatibility in Al-Li alloys using high energy diffraction microscopy and a crystal plasticity model
… delamination failure, and identified grain boundary shear as a driving force for delamination. The extent of localization may be controlled by precipitates, grain orientation, and grain interactions. The current work leverages in situ High Energy Diffraction Microscopy (HEDM) and polycrystal …
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High Resolution Measurements of the Mean Three-dimensional Flow Field in a Natural River
… quantify flow features including mean velocity, boundary shear stress, and sediment motion. Two survey procedures are typically employed with an ADCP. Moving-vessel (MV) measurements provide spatially-rich velocity data while temporally-rich data are obtained with fixed-vessel (FV) procedures. …
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Using Cross-sets for Paleodischarge Estimation and Paleocurrent Vectors in the Parthenon Sandstone, Northwest Arkansas
… channel belt width, channel width, paleoslope, boundary shear stress, Darcy-Weisbach friction factor, paleoflow velocity, paleodischarge, and overall paleocurrent direction. Paleodischarge estimates in this study average 13,000 m3/s; the minimum estimates average 2,200 m3/s; and the maximum …
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Stochastic estimation of near-wall closure in turbulence models
… best mean square estimator, is used to formulate boundary closure models for the numerical large eddy simulation (LES) of turbulence. The stochastic estimation method resolves coherent structure of the wall layer using empirical correlation functions, and provides an accurate estimation of the …
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Non-perennial streamflow & geomorphic patterns in a semi-arid rangeland slated for development
… and post-development distributed detention. Boundary shear stresses were used to compare the different simulations. Overall, the pre-development existing scenario had the lowest flows shear stresses for the two smallest storm scenarios (water quality capture volume and 2-year storms). For the …
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Sediment Heterogeneity and Sand Production in Gas Hydrate Extraction: Daini-Atsumi Knoll, Nankai Trough, Japan
… The results of these tests suggest the boundary shear stress of the fluid on the grains is a significant control on sand production for the Daini-Atsumi Knoll reservoir and the layering and grainsize structure of the sediments encourages sand production. Relative density of the sediments …
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Quantifying Near-Bank Turbulence Through a Storm Event
… failure. Fluvial entrainment, initiated by near-boundary turbulence, is one of the main drivers of streambank retreat as it leads to unstable streambank geometries. This research characterized the turbulent structure of flow near the toe of a streambank throughout a storm event, at times of high …
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Constitutive equations for granular materials : application to dry sand and powder metal
Strain localization into shear bands is commonly observed in natural soil masses, as well as in human-built embankments, footings, retaining walls and other geotechnical structures. Although the onset of strain localization can be derived from standard bifurcation analyses, few numerical …
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Dredge spoil dispersion from an inner shelf dump-mound
… rippled bed of fine sand during peak flow. Total boundary shear stresses indicate that stresses induced by waves are increased by the additional effect of currents. The current also provides a directional component to the stress. It is suggested that low threshold velocities on a gentle slope …
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Non-cohesive bank migration in meandering rivers and bank accretion in weakly braided rivers
… bank shape over the region where the critical shear stress is exceeded will be concave upward. Under conditions of uniform, fully-developed bend-flow, the transverse slope at the base of the bank (the channel thalweg) is demonstrated to be zero when considering boundaries consisting of uniform …
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Physical constraints on phytoplankton in estuaries and shallow coastal waters
… seemed solely governed by current velocities, shear and wind mixing events. Other passive constituents of the water column, such as suspended particulate matter, were also closely coupled with boundary shear and followed regular patterns of re-suspension similar to those shown by the diatom …
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In situ characterization of sediment oxygen demand across the spectrum of non-resuspension to full resuspension with varying bed shear stress
… dependence of SOD on near-bed velocity and bed shear stress prior to the point of sediment resuspension, there has been limited research that has attempted to characterize the complex and dynamic phenomenon of resuspended-sediment oxygen demand. To address this issue, a new in situ experimental …
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