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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Experimental Simulation on the pile toppling in the coast water

Tseng, Mei-hui 08 September 2007 (has links)
This paper studies the relationship between the degree of compactness of the pile structure foundation and how it will tilt under different wave condition. In the lab experiment setup, we use a periodic force generated by a magnetic coil to simulate the wave force impending on a scaled down model pile. With this setup, forces with different periods and magnitudes are used to find out the critical wave condition under which the pile will tilt, and it relationship with the results, engineering aspect of setting up a pile structure in the sea will have a better reference in the design stage.
2

Modeling Flows for Assessing Tidal Energy Generation Potential

Spurlock, Derek Scott 07 October 2008 (has links)
Tidal energy is a clean, sustainable, reliable, predictable source of energy. Recent developments in underwater turbines have made harvesting tidal energy feasible. Determining the power potential available in a given water body can be accomplished by using numerical hydraulic models to predict the flow velocity at a location of interest. The East River in Manhattan has been used here in an effort to develop a modeling methodology for assessing the power potential of a site. Two two-dimensional CFD models, FESWMS and TUFLOW, as well as one one-dimensional model, HEC-RAS, are used to analyze flows in the East River. Comparisons are made between the models and TUFLOW proves to best represent flows in the East River. HEC-RAS provides accurate results; however, the one-dimensional results lack the necessary detail of a two-dimensional model. FESWMS cannot produce results that mimic actual flow conditions in the East River. Using the TUFLOW model, power and energy estimates are made. These estimates show that a two-dimensional model, such as TUFLOW, can be a great tool for engineers and planners developing tidal energy projects. Using the results of this work, a methodology is developed to assess power potential at other sites using publicly available data. / Master of Science
3

Evacuation Timing Computations Using Different Evacuation Models

Tan, Yong Kiang January 2011 (has links)
In New Zealand, a new method of specific design, Verification Method 2 (C/VM2) has been proposed to be used for fire safety compliance. Previous researchers have investigated different fire parameters and their applications. However, there is a lack of research effort in evacuation calculations and in this research the author uses three different types of evacuation software to calculate the evacuation timings for four different buildings. These buildings include a cinema complex, a four-storey office building, a two-storey restaurant and a sport and recreation complex. Furthermore, this work conducts evacuation analyses to test the applicability of these evacuation tools. Simulex, FDS+Evac and EvacuatioNZ are the evacuation software used and the simulation results are compared with the hydraulic model recommended by C/VM2. Through careful analyses of the escape routes, the hydraulic model can be used to obtain evacuation times in a short timeframe. This calculation can be concise for a simple geometry, but lengthy for complex buildings. However, the hand calculation method has been found to be unsuitable in certain applications, for example buildings with specific seating arrangements, different occupant groups etc. FDS+Evac, in general, generates comparable evacuation times compared to the hydraulic model. As FDS+Evac has a good user interface, one can study the evacuation process easily. However, the computation time for one simulation can be relatively longer than with the other software tools. It was found that this tool is good for complex evacuation situations where a merging or counter-flow situation arises. Simulex, in general, generates faster evacuation times compared to the hydraulic model. Nevertheless, the computation time to complete one run is not too long and the evacuation process can be observed during and after the simulation. Finally, it was discovered that Simulex is not designed for counter-flow evacuation scenarios. EvacuatioNZ generates significantly longer evacuation timings in highly-congested evacuation scenarios, although for single spaces it has comparable results to hydraulic model. Some future work is required before this evacuation tool can be used as a design tool.
4

Development of a high-resolution 1D/2D coupled flood simulation of Charles City, Iowa

Moore, Matthew Roger 01 May 2011 (has links)
The development of a high-resolution coupled one-dimensional/two-dimensional hydrodynamic model of Charles City, Iowa is presented in this study as part of a larger Iowa Flood Center initiative to create a library of steady inundation maps for communities in Iowa which have a high risk of flooding. Channel geometry from bathymetric surveys and surface topography from LiDAR were combined to create the digital elevation model (DEM) used in numerical simulations. Coupled one- and two-dimensional models were used to simulate flood events; the river channel and structures were modeled one-dimensionally, and the floodplain was modeled two-dimensionally. Spatially distributed roughness parameters were estimated using the 2001 National Land Cover Dataset. Simulations were performed at a number of mesh resolutions, and the results were used to investigate the effectiveness of re-sampling simulation results using higher- resolution DEMs. The effect of removing buildings from the computational mesh was also investigated. During 2011, the stream channel geometry is being changed as part of a recreational park in downtown Charles City. After incorporating the planned changes to the stream channel, the model was used to create a library of steady inundation maps which are available on the Iowa Flood Center website.
5

Modelling retention time in a clearwell

Yu, Xiaoli 23 September 2009
Clearwells are large water reservoirs often used at the end of the water treatment process as chlorine contact chambers. Contact time required for microbe destruction is provided by residence time within the clearwell. The residence time distribution can be determined from tracer tests and is the one of the key factors in assessing the hydraulic behaviour and efficiency of these reservoirs. This work provides an evaluation of whether the two-dimensional, depth-averaged, finite element model, River2DMix can adequately simulate the flow pattern and residence time distribution in clearwells. One question in carrying out this modelling is whether or not the structural columns in the reservoir need to be included, as inclusion of the columns increases the computational effort required.<p> In this project, the residence time distribution predicted by River2DMix was compared to results of tracer tests in a scale model of the Calgary Glenmore water treatment plant northeast clearwell. Results from tracer tests in this clearwell were available. The clearwell has a serpentine baffle system and 122 square structural columns distributed throughout the flow. A comparison of the flow patterns in the hydraulic and computational models was also made. The hydraulic model tests were carried out with and without columns in the clearwell.<p> The 1:19 scale hydraulic model was developed on the basis of Froude number similarity and the maintenance of minimum Reynolds numbers in the flow through the serpentine system and the baffle wall at the entrance to the clearwell. Fluorescent tracer slug injection tests were used to measure the residence time distribution in the clearwell. Measurements of tracer concentration were taken at the clearwell outlet using a continuous flow-through fluorometer system. Flow visualization was also carried out using dye to identify and assess the dead zones in the flow. It was found that it was necessary to ensure the flow in the scale model was fully developed before starting the tracer tests, and determining the required flow development time to ensure steady state results from the tracer tests became an additional objective of the work. Tests were carried out at scale model flows of 0.85, 2.06, and 2.87 L/s to reproduce the 115, 280, and 390 ML/day flows seen in the prototype tracer tests.<p> Scale model results of the residence time distribution matched the prototype tracer test data well. However, approximately 10.5 hours was required for flow development at the lowest flow rate tested (0.85 L/s) before steady state conditions were reached and baffle factor results matched prototype values. At the intermediate flow, baffle factor results between the scale model and prototype matched well after only 1 h of flow development time, with improvements only in the Morril dispersion index towards prototype values with increased flow development time (at 5 h). Similar results were seen at the highest flow tested. For fully developed flow, there was little change in the baffle factor and dispersion index results in the scale model with varied flow rate.<p> With the addition of columns to the scale model, there was no significant change in the baffle factor compared to the case compared to without the columns, but up to a 13.9 % increase in dispersion index as compared to the tests in the scale model without columns for fully developed flow. Further, the residence time distribution results from the scale model tests without columns matched the entire residence time distribution found in the prototype tests. However, for the model with columns, the residence time distribution matched the prototype curve well at early times, but departed significantly from it at times later in the tests. It appears the major effect of the addition of columns within a model clearwell is to increase the dispersion index and increase the proportion of the clearwell which operates as a mixed reactor.<p> The results also showed there was good agreement between the physical model tests and River2DMix simulations of the scale model tests for both the flow pattern and residence time distributions. This indicates that a two-dimensional depth-averaged computer model such as River2DMix can provide representative simulation results in the case where the inlet flow is expected to be quickly mixed throughout the depth of flow in the clearwell.
6

Modelling retention time in a clearwell

Yu, Xiaoli 23 September 2009 (has links)
Clearwells are large water reservoirs often used at the end of the water treatment process as chlorine contact chambers. Contact time required for microbe destruction is provided by residence time within the clearwell. The residence time distribution can be determined from tracer tests and is the one of the key factors in assessing the hydraulic behaviour and efficiency of these reservoirs. This work provides an evaluation of whether the two-dimensional, depth-averaged, finite element model, River2DMix can adequately simulate the flow pattern and residence time distribution in clearwells. One question in carrying out this modelling is whether or not the structural columns in the reservoir need to be included, as inclusion of the columns increases the computational effort required.<p> In this project, the residence time distribution predicted by River2DMix was compared to results of tracer tests in a scale model of the Calgary Glenmore water treatment plant northeast clearwell. Results from tracer tests in this clearwell were available. The clearwell has a serpentine baffle system and 122 square structural columns distributed throughout the flow. A comparison of the flow patterns in the hydraulic and computational models was also made. The hydraulic model tests were carried out with and without columns in the clearwell.<p> The 1:19 scale hydraulic model was developed on the basis of Froude number similarity and the maintenance of minimum Reynolds numbers in the flow through the serpentine system and the baffle wall at the entrance to the clearwell. Fluorescent tracer slug injection tests were used to measure the residence time distribution in the clearwell. Measurements of tracer concentration were taken at the clearwell outlet using a continuous flow-through fluorometer system. Flow visualization was also carried out using dye to identify and assess the dead zones in the flow. It was found that it was necessary to ensure the flow in the scale model was fully developed before starting the tracer tests, and determining the required flow development time to ensure steady state results from the tracer tests became an additional objective of the work. Tests were carried out at scale model flows of 0.85, 2.06, and 2.87 L/s to reproduce the 115, 280, and 390 ML/day flows seen in the prototype tracer tests.<p> Scale model results of the residence time distribution matched the prototype tracer test data well. However, approximately 10.5 hours was required for flow development at the lowest flow rate tested (0.85 L/s) before steady state conditions were reached and baffle factor results matched prototype values. At the intermediate flow, baffle factor results between the scale model and prototype matched well after only 1 h of flow development time, with improvements only in the Morril dispersion index towards prototype values with increased flow development time (at 5 h). Similar results were seen at the highest flow tested. For fully developed flow, there was little change in the baffle factor and dispersion index results in the scale model with varied flow rate.<p> With the addition of columns to the scale model, there was no significant change in the baffle factor compared to the case compared to without the columns, but up to a 13.9 % increase in dispersion index as compared to the tests in the scale model without columns for fully developed flow. Further, the residence time distribution results from the scale model tests without columns matched the entire residence time distribution found in the prototype tests. However, for the model with columns, the residence time distribution matched the prototype curve well at early times, but departed significantly from it at times later in the tests. It appears the major effect of the addition of columns within a model clearwell is to increase the dispersion index and increase the proportion of the clearwell which operates as a mixed reactor.<p> The results also showed there was good agreement between the physical model tests and River2DMix simulations of the scale model tests for both the flow pattern and residence time distributions. This indicates that a two-dimensional depth-averaged computer model such as River2DMix can provide representative simulation results in the case where the inlet flow is expected to be quickly mixed throughout the depth of flow in the clearwell.
7

Study on The Application of FLOW-3D for Wave Energy Dissipation by a Porous Structure

Chen, Chun-Ho 11 September 2012 (has links)
Wave is one of the most common dynamic factors in marine engineering. This is the major affecting factor in the design of structures and coastal engineering that wave affect the structure or the coast, so there are many topics about wave absorbing issues. In this paper, FLOW-3D modeling is implemented for wave interaction with porous structures, and comparing with experiment. This is very different between the results of models using the proposed method by the FLOW-3D User Manual to set drag coefficients of porous media and the results of experiments. Therefore, to discuss the setting drag coefficients of porous media is one of this research project. Configuration of this study, four different types of porous structures to explore the interaction with wave, the major categories: single, double and three-tier (two forms). FLOW-3D simulations of wave boundary in this article is to simulate the wave plate to manufacture wave, FLOW-3D simulations of wave with the previous studies are different with its built-in wave boundary. The results of simulation compare with experiment, and obtain water depth data both of them, and then programmatically wave analysis explore the differences between simulation and experiment. The simulation results show that stroke set by the analog wave board need to reduce 10 percent of the original settings, and the simulation results are similar to experiment results. The differences between simulation and experiment are smaller when porous media parameter ¡¥b¡¦ setting formula adjust to 0.03/D ( D is the particle diameter)and parameter ¡¥a¡¦ setting formula changeless. Reducing wave of the four porous structures relate to the wave period. The wave period is bigger and more difficult to wave absorption, and the reflectivity is proportional to wave period.
8

Modeling the hydraulic characteristics of fully developed flow in corrugated steel pipe culverts

Toews, Jonathan Scott 25 September 2012 (has links)
The process of fish migration within rivers and streams is important, especially during the spawning season which often coincides with peak spring discharges in Manitoba. Current environmental regulations for fish passage through culverts require that the average velocity be limited to the prolonged swimming speed of the fish species present. In order to examine the validity of this approach, physical model results were used to calibrate and test a commercially available Computational Fluid Dynamics (CFD) model. Detailed analysis showed that CFD models and the empirical equations used were both able to give a better representation of the flow field than the average velocity. However, the empirical equations were able to provide a more accurate velocity distribution within the fully developed region. A relationship was then developed, to estimate the cumulative percent area less than a threshold velocity within CSP culverts, to be used as a guideline during the design phase.
9

Modeling the hydraulic characteristics of fully developed flow in corrugated steel pipe culverts

Toews, Jonathan Scott 25 September 2012 (has links)
The process of fish migration within rivers and streams is important, especially during the spawning season which often coincides with peak spring discharges in Manitoba. Current environmental regulations for fish passage through culverts require that the average velocity be limited to the prolonged swimming speed of the fish species present. In order to examine the validity of this approach, physical model results were used to calibrate and test a commercially available Computational Fluid Dynamics (CFD) model. Detailed analysis showed that CFD models and the empirical equations used were both able to give a better representation of the flow field than the average velocity. However, the empirical equations were able to provide a more accurate velocity distribution within the fully developed region. A relationship was then developed, to estimate the cumulative percent area less than a threshold velocity within CSP culverts, to be used as a guideline during the design phase.
10

Hazard map based on the simulation of sludge flow in a two-dimensional model, Case Quebrada Malanche-Punta Hermosa -Lima-Perú

Garcia, Luis Jimenez, Iruri Guzman, Osnar, Hurtado, Sissi Santos 30 September 2020 (has links)
El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / This research presents the numerical simulation to reproduce the transport and deposition processes of the sludge flow on March 15, 2017, strongly impacting the town of Pampapacta in Punta Hermosa-Peru.The debris flow initiation process in the basin was represented by hydrographs obtained from the estimated volumes of stormwater runoff and solid materials. The sludge flow was modeled in Flo2D to calculate hazard maps with the discharge event and others with different return periods.The numerical simulation results show acceptable results in relation to what happened. The model used to assess the hazard due to debris flow can predict and delineate, with acceptable precision, potentially hazardous areas for a landslide. The application of the proposed methodology to assess the hazard of disasters due to debris flows in basins and streams is useful to understand the extent of the impact of the mud flow during extreme weather events, as well as to develop emergency plans and formulate disaster policies.

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