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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

Validation of finite element couple level-set volume of fluid method for plunging breaking wave prediction

Hubbard, Graham 01 May 2020 (has links)
Predictive capability of computational fluid dynamics simulations for the prediction of plunging breaking wave is assessed. Laminar flow simulations are performed for dam break, solitary wave run up on a slope and flow over a submerged bump using OpenFOAM, a finite volume solver with volume-ofluid (VoF) interface capturing method, and Proteus, a finite element solver with coupled level-set/ volume-ofluid (CLSVoF) methods. CLSVoF predicts wave elevation before the plunge, and primary and secondary plunger shapes better than VoF in all the cases. The primary limitation in the simulation is the airflow, which results in diffused plunger tips in VoF simulations, and results in surface peel-off in CLSVoF simulations. Future work should include 3D turbulent flow simulations.
2

Breaking and curing rates in asphalt emulsions

Banerjee, Ambarish 30 January 2013 (has links)
This PhD dissertation addresses a number of issues pertaining to the use and application of surface treatments using asphalt emulsions. The work conducted as part of this research study shows in detail the problems associated with the state-of-practice and how these issues can be addressed using a scientific and rational approach as opposed to the experience-based approach which is prevailing currently. The first objective of this research study focuses on developing a methodology to determine the total amount of evaporative water loss of an emulsion before the aggregates are placed. An algorithm is presented that can be used by field inspectors and practitioners for the optimal timing of chip placement. The second objective focuses on another key aspect associated with the constructability of surface treatments, i.e., the optimal time to open a new surface treatment to traffic. Laboratory tests were conducted on the emulsion and aggregates to measure the rate of moisture loss and the evolution of the rheological properties as function of time. This was related to the field measured evaporation rates to determine the minimum stiffness required for optimal performance of the chip seal towards adequate resistance to raveling. The final objective of this dissertation focuses on developing a theoretical understanding of the current flowing through a circuit when an emulsion separates into its constituent phases when placed in an electric field. The measured current depends on a set of material properties that include the emulsion’s viscosity, surface potential, and dielectric of the medium and the strength of the electric field. A theoretical formulation was developed that relates the current flowing through the circuit with the mobility of the charged particles and the bulk charge density. The proposed theory was further utilized in developing a test procedure to quantify the breaking characteristics of asphalt emulsions. Results demonstrated that the parameters obtained from these tests were repeatable and different for different types of asphalt emulsions. It was also noticed that for a given type of emulsion the test method is sensitive to factors such as water content and partial breaking due to mechanical agitation. / text
3

An experimental investigation of the performance of glazing systems exposed to enclosure fires

Flood, Maura Fiona January 2003 (has links)
No description available.
4

Modelling the M-effect in H.R.C. fuses

Beaujean, David Alexander January 1991 (has links)
No description available.
5

Extreme wave impinging and overtopping

Ryu, Yong Uk 02 June 2009 (has links)
This investigates the velocity fields of a plunging breaking wave impinging on a structure through measurements in a two-dimensional wave tank. As the wave breaks and overtops the structure, so-called green water is generated. The flow becomes multi-phased and chaotic as a highly aerated region is formed in the flow in the vicinity of the structure while water runs up onto the structure. In this study, particle image velocimetry (PIV) was employed to measure the velocity field of the water dominant region. For measurements of an aerated region that cannot be measured by PIV, a new measurement method called bubble image velocimetry (BIV) was developed. The principle and setup of the BIV method were introduced and validated. Mean and turbulence properties were obtained through ensemble averaging repeated tests measured by both methods. The dominant and maximum velocity of the breaking wave and associated green water are discussed for the three distinct phases of the impingement-runup-overtopping sequence. The distribution of the green water velocity along the top of the structure has a nonlinear profile and the maximum velocity occurs near the front of the fast moving water. Using the measured data and applying dimensional analysis, a similarity profile for the green water flow on top of the structure was obtained, and a prediction equation was formulated. The dam breaking solution used for the green water prediction was examined with determining initial water depth based on the experiment conditions. Comparison between measurements, the prediction equation, and the dam breaking flow was made. The prediction equation and the dam break flow with appropriate initial water depth may be used to predict the green water velocity caused by extreme waves in a hurricane. To demonstrate the aeration of the breaking wave and overtopping water, void fraction was also investigated. There is strong aeration in the region of overtopping water front generated by a plunging breaker. Void fraction of overtopping water was measured using a fiber optic reflectometer (FOR). The measured velocity and void fraction were also used to estimate flow rate and water volume of overtopping water.
6

Assessment of function index and engineering measure for Taiwan fish harbors

Wu, Hsien-cheng 14 September 2006 (has links)
There are 231 fishing ports and harbors along the coast of Taiwan now and utilize the phenomenon on the low side of function as to some fishing ports and harbors. This research intends to investigate a practical evaluation index for breakwater reduction based on the functions of fishing ports and the re-utilization of coastal space, the factors of security of fishing ports, fishing environment, development of tourism and some other factors are taking into account while evaluating the breakwater. In the research approach, the statistic data of usability ratio on the breakwaters at the fishing ports in Taiwan is first summarized. Then, to investigate the visiting scholar different fields, such as expert, government's fishing policy unit and fisherman's group, etc. The factors for evaluating breakwater reduction and the weighting number for the standard quantification of evaluation indices are proposed and the feasibility is confirmed with the statistic analysis. Furthermore, the evaluation criteria for the implementation of the construction methods of breakwater reduction in a fishing port is devised, and the breakwater reduction at Hemei Fishing Port is taken as a demonstrative example to analyze the achievement of reduction work, hoping to provide the reference basis for the fishing port facility reduction works evaluation by each level of fishery authorities and to achieve the requirements of the policy for the reduction of water-breaking to construct the decrement of things.
7

The overturning of steep water waves

Jillians, William James January 1988 (has links)
No description available.
8

Computer aided design of ice clearing system for fields of broken ice

Shih, Liang. January 1983 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1983. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 113-114).
9

Gross-Pitaevskii Theory of the Rotating Bose Gas

rseiring@math.princeton.edu 10 October 2001 (has links)
No description available.
10

Noise Signatures Analysis of Nearshore Breaking Wave

Wu, Jian-Yi 23 August 2010 (has links)
¡@The ocean ambient noise of coast is mainly influenced by sea waves, boats or ships, or human¡¦s coast activities. Among them, most of the ambient noise is from the breaking wave noise caused by wind, and its frequency range is quite wide (0.5~50 kHz). The breaking wave noise mechanism of surf zone is very complex, and has a variety of signal features. In this research, the location is at the Sizih Bay near Kaohsiung Harbor. Hydrophone was used to collect the noise and the wave motion process of surf zone was recorded simultaneously with a digital video camera. It was shown from the experiment results, as the wave evolved in the surf zone, it would eventually become unstable and collapsed, so a large amount of air would be trapped in water and forming bubble clouds. The oscillating bubble cloud from breaking wave would generate high frequency sound. The results also indicated that when breaking wave reached the location hydrophone, a wide band pulse sound was generated with a level as high as 120 dB. In the analysis of each frequency (1k, 2k, 3k, 4k, 5k Hz), due to the oscillating effects air bubbles after breaking wave, the noise level at 2~5k Hz were higher as compared to that without breaking wave passing the hydrophone. The last result was also validated by the time integral of the noise energy through out the wave evolution. In addition to the process of breaking waves and residual air bubbles under breaking waves contributing to the breaking wave source, for example discussed in the study breaking wave¡¦s period and breaking wave height, the results from these two studies found, when the longer the breaking wave period , the breaking wave SPL will be bigger with the longer the breaking wave period. And in the breaking wave height, when the breaking wave height much higher, breaking wave SPL will be much bigger too. And learned from these two conclusions , breaking wave periods and height will make the breaking waves source level caused by changes.

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