The purpose of this research is to adapt and improve existing two-dimensional numerical tidal models so that they can cope with regions where the tide falls and rises to uncover and cover inter-tidal banks without incurring numerical shocks which may be caused by the discretization of time and space. This thesis presents a review of current practices in the numerical modelling of flooding and drying banks in two dimensions. A two-dimensional depth-averaged numerical model has been written and is presented. It is used as a tool with which to investigate various existing algorithms which represent the physical process of the wetting and drying of intertidal zones. An alternative method with which to represent the moving boundary has been developed. This method is free from disturbances usually caused by the implementation of a moving boundary in such a numerical scheme. A 2NM numerical model of the Wash, U.K., is run to provide hind-cast tidal data pertaining to a particular site and period. A field programme is established to provide validation data for the model. Finally, conclusions from the programme of research are drawn.

Thesis (Ph. D.)--University of Southern California, 2008. / Title from PDF title page (viewed on Feb. 16, 2010) Includes bibliographical references (p. 147-151). Also issued in print.

Thesis (M.S.)--Naval Postgraduate School, 1996. / "September, 1996." Includes bibliographical references (p. 169-177).

Thesis (M. S.)--Florida State University, 2006. / Advisor: Sergio Fagherazzi, Florida State University, College of Arts and Sciences, Dept. of Geology. Title and description from dissertation home page (viewed June 12, 2006). Document formatted into pages; contains ix, 83 pages. Includes bibliographical references.

An acoustic Doppler current profiler (ADCP) has been tried and found suitable for taking profiles of the time-mean three-dimensional velocity, vertical shear. Reynolds stress and turbulent kinetic energy (TKE) density in a coastal tidal channel. The velocity profiles have been used to reveal the existence of a log-layer. The data collected with the ADCP have been combined with fine- and microstructure data collected with a moored instrument (TAMI) to examine the TKE budget and turbulence characteristics in tidal flows. The ADCP was rigidly mounted to the bottom of the channel and the instrument was set to rapidly collect samples of along-beam velocities. In the derivation of the mean flow vector and the second-order turbulent moments, one must assume that the mean flow and turbulence statistics are homogeneous over the distance separating beam pairs. A comparison of the estimated mean velocity against the “error” velocity provides an explicit test for the assumption of homogeneity of the mean flow. The number of horizontal velocity estimates that pass a simple test for homogeneity increases rapidly with increasing averaging distance, exceeding 95% for distances longer than 55 beam separations. The Reynolds stress and TKE density are estimated from the variances of the along-beam velocities. Doppler noise causes a systematic bias in the estimates of the TKE density but not in the Reynolds stress. With increasing TKE density, the statistical uncertainty of the Reynolds stress estimates increases, whereas the relative uncertainty decreases. The spectra of the Reynolds stress and the TKE density are usually resolved; velocity fluctuations with periods longer than 20 minutes contribute little to the estimates. Stratification in the channel varies with the strength of the tidal flow and is weak below mid- depth. The ADCP measurements provide clear examples of secondary circulation, intense up/down- welling events, shear reversals, and transverse velocity shear. Profiles of the streamwise velocity are fitted to a logarithmic form with 1% accuracy up to a height, defined as the height of the log-layer, that varies tidally and reaches 20 m above the bottom during peak flows of 1 m s ⁻¹. The height is well predicted by 0.04u*/ω, where u * is the friction velocity and ω is the angular frequency of the dominant tidal constituent. The mean non-dimensional shear, [special characters omitted],is within 1% of unity at the 95% level of confidence inside the log-layer. Estimates of the rates of the TKE production and dissipation, eddy viscosity and diffusivity coefficients and mixing length, are derived by combining measurements with the ADCP and TAMI located at mid-depth. Near the bottom (z = 3.6 m), the production rate is 100 times larger than all other measurable terms in the TKE equation. Hence, the rate of production of TKE must be balanced by dissipation. The observed rate of production is proportional to the rate of dissipation calculated using the observed TKE density and mixing length, following the closure scheme of Mellor and Yamada (1974). This proportionality holds for the entire 3 decades of the observed variations in the rate of TKE production. At mid-depth, the eddy diffusivity of density and heat, deduced from microstructure measurements, agrees with the eddy viscosity derived from measurements with the ADCP. The scaling of the log-layer height with tidal frequency in the channel is comparable to the scaling with Coriolis parameter for the log-layer in steady planetary boundary layer. However, some results are inconsistent with those from boundary layers over horizontal homogeneous bottoms. The Reynolds stress is not constant within the log-layer, and its magnitude at 3.6 m above the bottom is 3 times smaller than the shear velocity squared [special characters omitted] derived from log-layer fitting. The peak of the non-dimensional spectrum for the Reynolds stress, when compared to measurements from atmospheric boundary layer, is shifted to higher wavenumbers by a factor of 2.5. One possible explanation for these discrepancies is the influence of horizontal inhomogeneity caused by bed forms. / Graduate

Thesis (Ph.D.)--Murdoch University, 2004. / Thesis submitted to the Division of Arts. Bibliography: p. 366-426.

A set of closely-spaced tide-gauge records of the 1960 Chilean tsunami was obtained on the Pacific Coast of Canada. The object of this study was to glean as much as possible of the information contained in these records. The investigation was carried on by power spectrum analysis, cross-spectrum analysis and visual inspection of the tide-gauge records. An interpretation is offered which invokes the mechanisms of wave buildup due to shoaling, clapotis effect, resonance, viscous dissipation, and shift of energy between wave and current by Reynolds stresses to explain the form of the power spectra. In the appendices are given a formula for the response characteristics of stilling wells, an application of an electrical engineering result for the response characteristics of pressure gauges, an elucidation of the conversion of power estimates to the positive frequency range, an interpretation of the phase difference from cross-spectra, and a formula for prewhitening the covariances before performing the Fourier transform in the spectral analysis. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Offshore wind has proved to be one of the most reliable and clean energy sources over the last few years. The industry has experienced a significant growth, with an increase of 101% only in 2017 compared to 2016. This raises the importance of the need for more secure power supply systems, which can be used for controlling the offshore farms during disconnections from the main grid. Nowadays, diesel generators are being used to feed auxiliary services of the offshore wind turbines in situations of emergency. However, as the marine renewable energy industry evolves, tidal energy parks have the potential to replace diesel generators and provide a more sustainable and eco-friendly solution for a long-term auxiliary power system. Moreover, they have the potential to produce extra power, which can be either stored for future use or linked directly to distribution. This report demonstrates a technical, financial and environmental assessment of a potential tidal park within an offshore wind park. Comparison with alternative sources for emergency power supply is also performed. Three alternative locations with high wind speeds and large tidal resource around the UK coast and four different groups of tidal devices are evaluated and compared for the implementation of this solution with the use of ArcGIS maps and other accessible marine data. The Aberdeen wind farm and the tidal kites are selected for further investigation and cost analysis. Seven tidal kites with average power 700 kW and rated power 3.5 MW can provide adequate power to the offshore wind farm for three months without grid connection, whereas they can also provide excess of energy on daily basis when grid disconnection does not occur. The total cost for the project would be approximately 301.6 MSEK. Due to the current renewable energy market, the project is not feasible without high investment risks. However, this study should be evaluated again in the near future when the cost of the tidal device will be further decreased. / Havsbaserad vind har visat sig vara en av de mest tillförlitliga och rena energikällorna under senare år. Inom denna industri har en betydande tillväxt skett, med en ökning med 101% år 2017 jämfört med 2016. Detta relaterar till behovet av säkra elförsörjningssystem, som kan användas för att styra havsbaserade vindraftverksparker under urkoppling från huvudnätet. Numera används dieselgeneratorer som reservkälla till havsvindkraftverk i nödsituationer. Men när den marina förnybara energiindustrin utvecklas, har tidvattenkraftverk potential att ersätta dieselgeneratorer och ge ett mer hållbar och miljövänlig långtidslösning. Dessutom har de potential att producera extra el, som antingen kan lagras för framtida användning eller kopplas direkt till distributionsnätet. Denna rapport erbjuder en teknisk, finansiell och miljömässig bedömning av en potentiell tidvattenkraftverkspark kopplad till en havsvindpark. Jämförelse med alternativa källor för strömförsörjning genomförs också. Tre alternativa platser med hög vindstyrka och stora tidvattenresurser längs Storbritanniens kust och fyra olika grupper av tidvattenanordningar utvärderas och jämförs med hjälp av kartor och andra tillgängliga marina data. Aberdeen vindkraftpark och tidvattendrakar väljs för ytterligare undersökning och kostnadsanalys. Sju tidvattendrakar med genomsnittlig effekt på 700 kW och nominell effekt 3,5 MW kan ge tillräckligt med el till havsvindkraftverk i tre månader utan nätförbindelse, medan de också kan ge överflöd av energi dagligen när strömavbrott inte förekommer. Den totala kostnaden för projektet skulle vara cirka 301,6 MSEK. På grund av läget idag på elmarknaden för förnybar energi, är projektet inte genomförbart utan höga investeringsrisker. Men den här studien bör utvärderas igen inom en snar framtid när kostnaden för tidvattenanordningen har minskat.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24169号 / 理博第4860号 / 新制||理||1695(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 田中 貴浩, 准教授 久徳 浩太郎, 教授 橋本 幸士 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

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