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31.
Implementation and evaluation of alternative wave breaking formulas in a coastal spectral wave model 总被引：2，自引：0，他引：2
This paper describes methods and results of research for incorporating four different parameterized wave breaking and dissipation formulas in a coastal wave prediction model. Two formulations assume the breaking energy dissipation to be limited by the Rayleigh distribution, whereas the other two represent the breaking wave energy by a bore model. These four formulations have been implemented in WABED, a directional spectral wave model based on the wave action balance equation with diffraction, reflection, and wave–current interaction capabilities. Four parameterized wave breaking formulations are evaluated in the present study using two high-quality laboratory data sets. The first data set is from a wave transformation experiment at an idealized inlet entrance, representing four incident irregular waves in a slack tide and two steady-state ebb current conditions. The second data set is from a laboratory study of wave propagation over a complex bathymetry with strong wave-induced currents. Numerical simulation results show that with a proper breaking formulation the wave model can reproduce laboratory data for waves propagating over idealized or complicated bathymetries with ambient currents. The extended Goda wave breaking formulation with a truncated Rayleigh distribution, and the Battjes and Janssen formulation with a bore model produced the best agreement between model and data. 相似文献
32.
Nonlinear contributions due to elevation of the free surface, the dynamic head, and the second-order velocity potential on the wave loads are presented in closed-form expressions. Such nonlinearities resulting from large-amplitude ocean waves are associated with the irrotational flow interacting with a fixed bottom-mounted vertical cylinder piercing the surface. These are expressed in the form of dynamic, waterline and quadratic forces all of which depend on the square of the wave amplitude. The appropriate modifications are made to both the classical Morison equation and the well-known linear diffraction theory of MacCamy and Fuchs for accounting the second-order effects.A limited comparative study is performed to verify the present theoretical derivations. In general, satisfactory agreements have been obtained with the test results from various laboratory studies by different researchers. However, under certain environmental conditions, some discrepancies still exist with the measured results. 相似文献
33.
Zeki Demirbilek 《Ocean Engineering》1983,10(5):359-374
In Part I of these series of papers, the complete problem formulation in a linearized form was presented. In order to provide the engineer with an in-depth knowledge about the exact solution of the problem, it is natural and essential to start with a linear solution. This will be the objective of Part II, together with an exposition to the analysis of numerical technique utilized.A truncated infinite Fourier series-type solution is adopted for the linearized boundary value problem. It is shown that such a solution is mathematically consistent and represents the phenomenon properly by satisfying all of the field equations and the imposed boundary conditions. The dependence of the Fourier coefficients on the truncation limit has been investigated. The best lower and upper “cutoff limits” for the truncation of an infinite series are determined. An error analysis of the solution technique is performed. 相似文献
34.
Morpho-tectonic evolution of the Marmara Sea inferred from multi-beam bathymetric and seismic data 总被引：1，自引：6，他引：1
Erkan?Goka?anEmail author Timur?Usta?mer Cem?Gazio?lu Zeki?Ya?ar?Yucel Kurultay??ztürk Hüseyin?Tur Berkan?Ecevito?lu Bu?ser?Tok 《Geo-Marine Letters》2003,23(1):19-33
In an initial stage, the Sea of Marmara developed as a graben and, in due course, considerable volumes of sediments were deposited in this basin. Before 200 ka, a new fault (New Marmara Fault) cutting through the whole basin developed, which postdated large sub-marine land sliding in the western part of the basin. This mass movement created the Western Ridge. The initiation of this strike-slip fault indicates that the extensional stress regime was replaced by a new, shearing stress field. In the eastern part of the Marmara Basin, the New Marmara Fault consists of two branches. The northern one replaces the normal faulting at the bottom of the northeastern slope of the basin. As a result, this slope has been rejuvenated. The southern branch is located along the central axis of the basin, forming the major extension of the North Anatolian Fault Zone within the region. Two restraining bends were formed because of the counterclockwise rotation of that part of the Anatolian Block. This resulted the uplifting of the Eastern Ridge and the formation of the positive flower structure within the Tekirdag Basin. The establishment of the compressional regime around the Sea of Marmara also resulted in the northwest–southeast shortening of the initial Marmara Basin. 相似文献
35.
The multicolor light curves (UBVRI) of HU Vir have been analyzed to study starspots for epochs 1987 and 1989. The term 'photometric
imaging' has been used for predicting cool surface spots by photometric data. Assuming the number of spots and the area are
about the same for the two hemispheres, the distributive solar analogy is introduced as a tool to constrain free values of
spot parameters into unique values. Therefore, final fitting parameters are claimed unique in a sense that they are independent
of free initial guesses. The light and color variations of HU Vir are better explained without polar spots. Finally, the spots
are found to be ∼ 1600 K cooler than the T∼ 5000 K of this cool subgiant and cover ∼ %13.9 of the total surface at ±8.0 degrees
from the equator for the epoch 1987. The spots at the epoch 1989 are found to be ∼ 2040 K cooler covering ∼ % 12.7 area at
± 27°.7 latitudes. Problems of photometric imaging and possible solutions with distributive solar analogy have been discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
36.
Three aquifer systems as deep, middle, and shallow were identified in the Kazan trona ore deposit area. The flow conditions
and the interaction between various layers were conceptualized into a site hydrogeological model. Each aquifer system was
hydraulically and chemically characterized and represented in a numerical groundwater model. The resulting model has been
calibrated under steady-state and transient conditions using available data. The flow model was used in conjunction with a
three-dimensional solute transport model to assess the impacts of the pilot well solution mining of the trona deposit on groundwater
resources during operation and post-operation periods. The results of operation period indicate that, even under the worse
conditions (50 times increase in vertical hydraulic conductivity due to subsidence), ion contribution from the mine area with
118,000 mg/l maximum concentration would be about 58 mg/l into the deep aquifer system. This contribution is about 1.45% of
the existing concentration (4,000 mg/l) in the deep aquifer. After 1,000 years of post-operation period, ion contribution
from the mine area with maximum 119,000 mg/l concentration would be about 205 mg/l into the deep aquifer under extremely worse
conditions. This contribution is about 5–20% of present concentrations in the deep aquifer. Retardation factors, which were
not considered during model simulations would decrease the predicted concentrations. It is concluded that pilot well solution
mining of the trona deposit would not have significant impact on the quality of groundwater resources in the overlying aquifers. 相似文献
37.
An artificial water canal opening is planned between the Agean Sea and the historical Ephesus site for the sake of tourism in the Selçuk sub-basin. In order to predict the effects of the planned canal on freshwater–seawater interface and related contamination in the aquifer, 3-D numerical density dependent flow and solute transport simulations were carried out. The simulations included the pre-pumping and pumping periods without a canal and the prediction period in the presence of the canal. Chloride concentration comparisons of the results obtained from the pre-pumping period and the pumping period indicate that the freshwater-seawater interface in the aquifer has progressed inland due to artificial discharge in the sub-basin. Drawdown during the pumping period is about 15 cm. The planned canal opening could further lower the groundwater levels in the area and would change the groundwater flow directions in the first 4 years. Then the levels and flow directions will nearly recover. However, the canal opening could cause further seawater intrusion into the aquifer to the extent that groundwater would be unfit to use for irrigation after the seventh year of the canal opening in the irrigation cooperative II wells area and would be unfit to use for drinking purposes after the tenth year in the municipality wells area located at the south of the cooperative II wells. On the other hand, the cooperative I wells would not be effected by the opening of the canal. 相似文献
38.
Abstract. seasonal sampling of three stations in Gulbahce Bay Aegean Sea for the zoobenthic organisms associated with a Zostera marina bed was carried out during 1993–94. Temperature, salinity and oxygen were recorded each sampling period. A total of 7 taxonomic groups were determined: Polychaeta was the dominant group comprising 77 % of the total taxa and individuals, followed by Crustacea, Bivalvia and other groups such as Nemertea. Sipuncula, Turbellaria and Phoronida. Of the 108 taxa encountered, the polychaetes Notomastus latericeus and Caulleriella alata accounted for 49 % of the total populations. The species abundance did not show major changes among seasons, with highest values in fall 982 indiv. ·m-2 and lowest in spring 754 indiv. ·m-2 . Diversity and evenness of the samples were relatively high and fairly constant, and were affected by the dominance levels of the species. 相似文献