The hydraulic analysis of culverts is complicated when using hand calculations. Fortunately, several computer programs are available to assist in analyzing culvert hydraulics, some of which include HY-8, Fish X-ing, Broken-back Culvert Analysis Program (BCAP), Hydraflow Express, Culvert Master, Culvert, and Hydrologic Engineering Center River Analysis System (HEC-RAS). While all of these programs can simulate the behavior of flow through a culvert, slightly different methodologies are utilized among the programs to complete a full hydraulic analysis, resulting in different predictions for headwater depth, flow control, and outlet velocities. The purpose of this paper is to compare (1) the available hydraulic features and (2) the numerical solutions from the seven programs to manually computed values. Four test cases were developed to test the accuracy of program results. The headwater depths and outlet velocities were compared to those obtained through calculations based on culvert hydraulic theory outlined in the Federal Highway Administration publication, Hydraulic Design Series 5. Based on the results, Fish X-ing was unable to analyze culverts under inlet control, while Culvert incorrectly predicted inlet control headwater depths at low flow conditions. Hydraflow Express struggled to predict correct outlet control headwater depths while BCAP had difficulty analyzing straight barrel culverts acting under outlet control. Overall, HY-8, Culvert Master, and HEC-RAS produced accurate results most consistently.

A skid steer loader is a machine used in construction for multiple tasks. Its small size and versatility makesit a use-full addition to any work site. The machine is driven by a combustion engine that in turn powers ahydraulic pump. This hydraulic fluid from the pump is then directed to either motor to propel the vehicle. Twospeed motors are used to allow high-speed operation. A problem present in the current design of the hydraulicsystem for a skid steer loader is its tendency to jerk when shifting speed at low temperatures. In an effort toidentify potential problems and rectify those, two models will be constructed in Simulink. One is a model ofthe whole system, where the pump and both motors are included as well as the machine itself. The other modelis designed to predict the system behaviour of one motor and a pump in a flywheel test rig. Also auxiliarycomponents are included in the models, including the two-speed shifting valve and pressure release valves. Bothmodels will predict the system behaviour from a set of input variables, including temperature, oil viscosity andgeometrical parameters. Improvements to the design where identified by analysing the simulation data. It wasfound that system performance could be enhanced by switching to an alternative notch shape of the two-speedshifting valve.

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Many of the free surface flow problems encountered by hydraulic engineers can be suitably analyzed by means of the depth-integrated equations of motion. A consequence of adopting a depth-integrated modeling approach is that closure approximations must be implemented to represent the so-called effective stresses. The effective stresses consist of the depth-integrated viscous stresses, which are usually small and neglected, the depth-integrated turbulent Reynold's stresses, and additional stresses resulting from the depth-integration of the nonlinear convective accelerations (here after called momentum dispersion). Existing closure schemes for momentum dispersion lack sufficient numerical and experimental verification to warrant consideration at this time, so consequently, attention is focused on examining closure for the depth-integrated turbulent Reynold's stresses. In the present study, an application at the depth-integrated (k-ε) turbulence model is presented for separated flow in a wide, shallow, rectangular channel with an abrupt expansion in width. The well-known numerical problems associated with the use of upwind and central finite differences for convection is overcome by the adoption of the spatially third-order accurate QUICK finite difference technique. Results presented show that modification of the depth-integrated (k-ε) turbulence closure model for streamline curvature leads to significant improvement in the agreement between model predictions and experimental measurements. / Ph. D.

A dimensionless equation is developed which describes the flow profile in rectangular channels with spatially varied flow. This equation is solved for various slopes and rates of discharge. The results show that when the slope and roughness are constant the dimensionless profiles are also constant over a very wide range of discharge. Once the dimensionless profile is established the water surface curve may be rapidly and accurately determined. Tests were conducted in the laboratory which reasonably verified the validity of the dimensionless profiles. / Master of Science

Yes / Within river systems, the process of bed-forming is intricate, dynamic and is shaped by different factors. Hydraulic forces exerted by water flow play a crucial role, forming the bed substrate over time. Additionally, the presence of vegetation within the riverbed and along its banks introduces further complexity, as the interaction between plants and hydrodynamics can alter sediment transport patterns and riverbed morphology. The movement of both suspended particles and bedload materials within the water column contributes to the ongoing riverbed landscape evolution. The primary aim of this editorial collection is to assemble an extensive range of research methodologies aimed to inform engineering practices pertinent to river management. Through an exhaustive exploration of various topics, including water quality indexing, erosion and sedimentation patterns, influence of vegetation, hydrological modelling for understanding flow dynamics, and identification of critical hydraulic parameters with the utilisation of both analytical and experimental modelling techniques, this paper endeavours to provide valuable insights derived from rigorous research efforts. By synthesising and presenting these findings, we offer a resource that can effectively guide future endeavours in river engineering and related disciplines.

No / In the search for sustainable city solutions, engineers face a bottleneck situation in balancing development and the intensified environmental challenges induced by scaled-up flooding, over-grown river vegetation, sediment transport, bridge and coastal scouring, and excessive pollution. The coupling impacts of uncontrolled flood and sediment to a city has caused difficulty in its management. Various numerical, theoretical, and experimental approaches have been proposed to reproduce flow and sediment transport conditions in real-world urban rivers, in order to perfect management strategies for them. This reprint, which is built from a well-planned journal’s Special Issue, aims to construct a collection of state-of-the-art studies and technologies to give insights to the related environmental, river, and sustainable city research and engineering communities. It is related and, hence, useful for environmental, river, and hydraulic engineers, authorities, and researchers to understand the current state-of-the-art practices in urbanized flow modelling, as well as vegetation- and sediment-related management. It also serves as a good knowledge source for research, post- or undergraduate students, in terms of knowledge about the most up-to-date topical advances.

The responsibility for mitigation of the ecological effects of urban stormwater runoff has been delegated to local government authorities through the Clean Water Act's National Pollutant Discharge Elimination Systems' Stormwater (NPDES SW), and Total Maximum Daily Load (TMDL) programs. These programs require that regulated entities reduce the discharge of pollutants from their storm drain systems to the "maximum extent practicable" (MEP), using a combination of structural and non-structural stormwater treatment — known as stormwater control measures (SCMs). The MEP regulatory paradigm acknowledges that there is empirical uncertainty regarding SCM pollutant reduction capacity, but that by monitoring, evaluation, and learning, this uncertainty can be reduced with time. The objective of this dissertation is to demonstrate the existing sources and magnitude of variability and uncertainty associated with the use of structural and non-structural SCMs towards the MEP goal, and to examine the extent to which the MEP paradigm of iterative implementation, monitoring, and learning is manifest in the current outcomes of the paradigm in Virginia. To do this, three research objectives were fulfilled. First, the non-structural SCMs employed in Virginia in response to the second phase of the NPDES SW program were catalogued, and the variability in what is considered a "compliant" stormwater program was evaluated. Next, the uncertainty of several commonly used stormwater flow measurement devices were quantified in the laboratory and field, and the importance of this uncertainty for regulatory compliance was discussed. Finally, the third research objective quantified the uncertainty associated with structural SCMs, as a result of measurement error and environmental stochasticity. The impacts of this uncertainty are discussed in the context of the large number of structural SCMs prescribed in TMDL Implementation Plans. The outcomes of this dissertation emphasize the challenge that empirical uncertainty creates for cost-effective spending of local resources on flood control and water quality improvements, while successfully complying with regulatory requirements. The MEP paradigm acknowledged this challenge, and while the findings of this dissertation confirm the flexibility of the MEP paradigm, they suggest that the resulting magnitude of SCM implementation has outpaced the ability to measure and functionally define SCM pollutant removal performance. This gap between implementation, monitoring, and improvement is discussed, and several potential paths forward are suggested. / Ph. D. / Responsibility for mitigation of the ecological effects of urban stormwater runoff has largely been delegated to local government authorities through several Clean Water Act programs, which require that regulated entities reduce the discharge of pollutants from their storm drain systems to the “maximum extent practicable” (MEP). The existing definition of MEP requires a combination of structural and non-structural stormwater treatment – known as stormwater control measures (SCMs). The regulations acknowledge that there is uncertainty regarding the ability of SCMs to reduce pollution, but suggest that this uncertainty can be reduced over time, by monitoring and evaluation of SCMs. The objective of this dissertation is to demonstrate the existing sources and magnitude of variability and uncertainty associated with the use of structural and non-structural SCMs towards the MEP goal, and to examine the extent to which the MEP paradigm of implementation, monitoring, and learning appears in the current outcomes of the paradigm in Virginia. To do this, three research objectives were fulfilled. First, the non-structural SCMs employed in Virginia were catalogued, and the variability in what is considered a “compliant” stormwater program was evaluated. Next, the uncertainty of several commonly used stormwater flow measurement devices were quantified in the laboratory and field, and the importance of this uncertainty for regulatory compliance was discussed. Finally, the third research objective quantified the uncertainty associated with structural SCMs, as a result of measurement error and environmental variability. The impacts of this uncertainty are discussed in the context of the large number of structural SCMs prescribed by Clean Water Act programs. The outcomes of this dissertation emphasize the challenge that uncertainty creates for cost-effective spending of local resources on flood control and water quality improvements, while successfully complying with regulatory requirements. The MEP paradigm acknowledged this challenge, and while the findings of this dissertation confirm the flexibility of the MEP paradigm, they suggest that the resulting magnitude of SCM implementation has outpaced the ability to measure and functionally define SCM pollutant removal performance. This gap between implementation, monitoring, and improvement is discussed, and several potential paths forward are suggested.

This study explores the design, testing, and modeling of a bubble injector intended for use in studying bubble dynamics in molten salt reactors using a room temperature surrogate fluid by matching the Reynolds number, Eötvös number, and Morton number defined by the properties of the helium bubbles in the pump bowl of the Molten Salt Reactor Experiment (MSRE). The injector, constructed from polydimethylsiloxane (PDMS) and acrylic, was tested to generate bubbles within a precise size range suitable for simulating conditions in molten salt reactors. Experimental data showed that the equivalent bubble diameter is directly proportional to gas flow rate and inversely proportional to liquid flow rate, with clear trends emerging when data were subdivided into constant flow rate plots. The study applied and adapted the bubble size control model proposed by Lu et al. (2014), revealing limitations in existing models under modified conditions such as an elongated two-phase channel. A novel model was developed to better predict bubble size, incorporating dependencies on both flow rate ratios and the capillary number of the microchannels. The injector's design facilitates convenient modifications in channel geometry to achieve target bubble sizes, and future improvements in pressure monitoring and imaging are recommended. This work contributes to the advancement of microfluidic bubble injection technology. / Master of Science / This study focuses on developing and testing a device that creates tiny bubbles to help us better understand bubble behavior in advanced nuclear reactors, specifically molten salt reactors. These reactors use a special type of liquid fuel, and understanding how bubbles move within them is important for improving their efficiency and safety. To simulate the conditions inside these reactors without using the actual molten salt, we used a substitute fluid that has similar properties to the molten salt and built a bubble injector made from clear, flexible materials. Our experiments showed that the size of the bubbles depends on the flow rates of the gas and liquid: larger bubbles are formed when more gas is injected, and smaller bubbles are created when the liquid flow is increased. We tested existing models that predict bubble size and found that they didn't always work well under the conditions we used, like longer channels where the gas and liquid mix. As a result, we developed a new model that better predicts bubble size by considering both flow rates and the Capillary number of the microchannels. The design of our injector allows for easy adjustments to make bubbles of different sizes, and we suggest future improvements in pressure measurement and camera equipment to enhance data accuracy.