Numerical Study on Instantaneous Discharge of Unsorted Particle Cloud in Cross Flow     

顾杰  李志伟杨红 詹咏 《中国海洋工程》2007,21(2):305-316

The mixing characteristics of particles such as dredged sediment of variable size discharged into cross flow are studied by a 3D numerical model, which is developed to model the particle-fluid two-phase flow. The Eulerian method with the modified k-ε parameterization of turbulence for the fluid phase is used to solve fluid phase, while a Lagrangian method for the solid phase (particles), both the processes are coupled through the momentum sources. In the model the wake turbulence induced by particles has been included as additional source term in the k-ε model; and the variable drift velocities of the particles are treated efficiently by the Lagrangian method in which the particles are tracked explicitly and the diffusion process is approximated by a random walk model. The hydrodynamic behavior of dumping a cloud of particles is governed by the total buoyancy of the cloud, the drag force on each particle and the velocity of cross-flow. The computed results show a roughly linear relationship between the displacement of the frontal position and the longitudinal width of the particle cloud. The particle size in the cloud and the velocity of cross flow dominate the flow behavior. The computed results are compared with the results of laboratory experiments and satisfactory agreement is obtained.  相似文献   

The Mathematical and Parameterized Expressions for Wave Induced Excess Flow of Momentum     

朱首贤丁平兴  张文静 《中国海洋工程》2007,21(1):137-146

Wave induced excess flow of momentum(WIEFM)is the averaged flow of momentum over a wave period due to wave presence,which may also be called 3-D radiation stress.In this paper,the 3-D current equations with WIEFM are derived from the averaged Navier-Stokes equations over a wave period,in which the velocity is separated into the large-scale background velocity,the wave particle velocity and the turbulent fluctuation velocity.A concept of wave fluctuating layer(WFL)is put forward,which is the vertical column from the wave trough to wave ridge.The mathematical expressions of WIEFM in WFL and below WFL are given separately.The parameterized expressions of WIEFM are set up according to the linear wave theory.The integration of WIEFM in the vertical direction equals the traditional radiation stress(namely 2-D radiation stress)given by Longuet-Higgins and Stewart.  相似文献   

The Levant Slumps and the Phoenician Structures: collapse features along the continental margin of the southeastern Mediterranean Sea     

Yossi Mart  William Ryan 《Marine Geophysical Researches》2007,28(4):297-307

Two distinct series of slumps deform the upper part of the sedimentary sequence along the continental margin of the Levant. One series is found along the base of the continental slope, where it overlies the disrupted eastern edge of the Messinian evaporites. The second series of slumps transects the continental margin from the shelf break to the Levant Basin. It seemed that the two series were triggered by two unrelated, though contemporaneous, processes. The shore-parallel slumps were initiated by basinwards flow of the Messinian salt, that carried along the overlying Plio-Quaternary sediments. Seawater that percolated along the detachment faults dissolved the underlying salt to form distinctly disrupted structures. The slope-normal slumps are located on top of large canyons that cut into the pre-Messinian sedimentary rocks. A layer of salt is found in the canyons, and the Plio-Quaternary sediments were deposited on that layer. The slumps are bounded by large, NW-trending faults where post-Messinian faulted offset was measured. We presume that the flow of the salt in the canyons also drives the slope-normal slumps. Thus thin-skinned halokynetic processes generated the composite post-Tortonian structural patterns of the Levant margin. The Phoenician Structures are a prime example of the collapse of a distal continental margin due to the dissolution of a massive salt layer.  相似文献   

波浪作用下岸坡和海底平衡条件的研究     

沈剑平  范德江 《中国海洋大学学报(自然科学版)》1993,(4)

提出波浪作用下岸坡和海底动态和静态平衡条件的数学模型。在已建立的推移质泥沙体积输沙率基本关系式的基础上,根据连续方程,计算出底坡、泥沙、波浪三要素在动态和静态平衡情况下的关系式,得出反映这种关系的底坡平衡函数曲线图。用实际资料对这一函数曲线进行了验证,并对实际资料相对模型的某些差异作出解释。  相似文献   

Bacterial sulphate reduction in sediments of a european salt marsh: Acid-volatile and tin-reducible products     

D. B. Nedwell  S. Takii 《Estuarine, Coastal and Shelf Science》1988,26(6)

The products of ³⁵S-sulphate reduction by sedimentary bacteria were measured at two sites in a salt marsh on the east coast of England. Non-acid-volatile products were measured, after acid-volatile sulphide was removed, by their reduction to sulphide by digestion with tin. The proportion of the sulphate reduced to tin-reducible products varied between 25% in a salt marsh pan and 61% in creek sediment, over a 0–25 cm depth profile. There were also variations with depth at each site in the proportions of sulphate reduced to tin-reducible products. Further examination revealed differences in the proportions of sulphate which were reduced to free sulphide, acid-volatile sulphide, sulphur or pyrite at the two sites. The data suggest that previous work which did not measure non-acid-volatile products underestimated sulphate reduction rates by three-fold in the creek site, but by only one third in the pan.  相似文献   

A perturbation solution for nonlinear structural response to oscillatory flow     

A.W. Lipsett   《Applied Ocean Research》1986,8(4):183-189

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Computation of Viscous Uniform and Shear Flow over A Circular Cylinder by A Finite Element Method     

赵明  滕斌 《中国海洋工程》2004,18(2):267-280

The incompressible viscous uniform and shear flow past a circular cylinder is studied. The two-dimensional Navier-Stokes equations are solved by a finite element method. The governing equations are discretized by a weighted residual method in space. The stable three-step scheme is applied to the momentum equations in the time integration. The numerical model is firstly applied to the computation of the lid-driven cavity flow for its validation. The computed results agree well with the measured data and other numerical results. Then, it is used to simulate the viscous uniform and shear flow over a circular cylinder for Reynolds numbers from lO0 to lO00. The transient time interval before the vortex shedding occurs is shortened considerably by introduction of artificial perturbation. The computed Strouhal number, drag and lift coefficients agree well with the experimental data. The computation shows that the finite element model can be successfully applied to the viscous flow problem.  相似文献   

东营凹陷王家岗地区王古1潜山构造特征及油气成藏条件     

侯方辉  李三忠  王金铎  于建国  吕海青  许淑梅 《中国海洋大学学报(自然科学版)》2007,37(2):341-344,322

进一步了解王古1潜山的构造特征及成藏条件,利用渤海湾盆地济阳坳陷东营凹陷王家岗地区的大量三维地震剖面和一些钻井资料,并结合东营凹陷南坡缓坡带区域构造背景及成藏条件分析认为,王古1潜山初始发育于印支期,后经燕山期拉张断陷,切割为断块并抬升,最后于燕山期定型,为典型的缓坡盆倾残丘潜山。该潜山被NW向和NE向断裂切割,潜山高部位侵蚀风化严重,上覆孔店组盖层及沙河街组烃源岩,油气通过断层和不整合面运移至潜山顶部形成侵蚀残丘型油气藏。  相似文献   

Artificial Upwelling of Deep Seawater Using the Perpetual Salt Fountain for Cultivation of Ocean Desert     

Shigenao Maruyama  Koutaro Tsubaki  Keisuke Taira  Seigo Sakai 《Journal of Oceanography》2004,60(3):563-568

Deep seawater in the ocean contains a great deal of nutrients. Stommel et al. have proposed the notion of a “perpetual salt fountain” (Stommel et al., 1956). They noted the possibility of a permanent upwelling of deep seawater with no additional external energy source. If we can cause deep seawater to upwell extensively, we can achieve an ocean farm. We have succeeded in measuring the upwelling velocity by an experiment in the Mariana Trench area using a special measurement system. A 0.3 m diameter, 280 m long soft pipe made of PVC sheet was used in the experiment. The measured data, a verification experiment, and numerical simulation results, gave an estimate of upwelling velocity of 212 m/day. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Pressure prediction in the Bullwinkle Basin through petrophysics and flow modeling (Green Canyon 65, Gulf of Mexico)     

P.B. Flemings  J.A. Lupa   《Marine and Petroleum Geology》2004,21(10):1311-1322

Reservoir pressures within the Bullwinkle minibasin (Green Canyon 65, Gulf of Mexico continental slope) increase at a hydrostatic gradient whereas pressures predicted from porosity within mudstones bounding these reservoirs increase at a lithostatic gradient: they are equal at a depth 1/3 of the way down from the crest of the structure. Two- and three-dimensional steady-state flow models demonstrate that bowl-shaped structures will have lower pressures than equivalent two-dimensional structures and that if a low permeability salt layer underlies the basin, the pressure is reduced. We conclude that at Bullwinkle, pressure is reduced due to an underlying salt body and the bowl-shape of the basin. A geometric approach to predict sandstone pressure is to assume that the reservoir pressure equals the area-weighted average of the mudstone pressure. When the mudstone pressure gradient is constant, as at Bullwinkle, the reservoir pressure equals the mudstone pressure at the average depth (centroid) of the reservoir.  相似文献