EFFECTS OF WATER-DEPTH ON HYDRODYNAMIC FORCE OF ARTIFICIAL REEF

The effects of water-depth on the hydrodynamic force of the artificial reef were studied by simulating regular and irregular waves. The computational results show that the water-depth has a substantial effect on hydrodynamic force. The hydrodynamic force increases with the decrease of water-depth in shallow. Especially, in the ultra-shallow water these loads increase very evidently with the decrease of water-depth. The long-term values of hydrodynamic force increase with the decrease of the ratio of water-depth to reef height, and are about 10% larger than those of deep water when the ratio of water-depth to reef height is 4.0. However water-depth hardly affects the long term values of hydrodynamic force when the ratio of water-depth to reef height is larger than 6.0.     

CALCULATION OF MANOEUVERING HYDRODYNAMIC FORCE INCLUDING THE EFFECT OF VISCOSITY

Based on the method of Chapman and Yamasaki, this paper calculates the wave making hydrodynamic forces acting on a yawed ship. In order to study the effect of viscosity, this paper calculates the wave making resistance of a new ship model whose boundary is formed by adding the displacement thickness on real ship body. The comparisons between the calculated results of a Wigley model and experimental values verify the validity of the new model and the numerical methods.     

LABORATORY STUDIES ON WAVE FORCE OF COASTAL STRUCTURES MADE OF FLAT GEOTUBES

Flat geotubes are widely used for coastal structures such as seawalls, breakwaters and sightseeing groins, etc.. However, the understanding of the stable mechanism involved in the wave-structure interactions should be deepened, and one of the important work is to clarify the stress state of the structure under the wave action. In this article, wave force acting on coastal structures made of flat geotube is experimentally investigated. The required drag, inertia and lift coefficients are especially analyzed from the results of hydraulic model experiments specially designed for geotube structure. Several types of structures made of flat geotubes under wave action have been tested in order to understand the stress state of the geotube fixed to force transducer within different structures. Experimental results show that the wave-induced forces on the instrumented geotube are markedly influenced by wave elements. Meanwhile, the magnitude of horizontal force of adjoining geotube is different at the same time.     

HYDRODYNAMIC MODEL OF THE WEIS-FOGH HYDROFOIL

ＨＹＤＲＯＤＹＮＡＭＩＣＭＯＤＥＬＯＦＴＨＥＷＥＩＳ－ＦＯＧＨＨＹＤＲＯＦＯＩＬＺｈａｎｇＳｈｅ－ｓｈｅｎｇ；ＷｕＸｉｕ－ｈｅｎｇ；ＷａｎｇＸｉａｎ－ｆｕ（Ｄｅｐａｒｔｍｅｎｔｏｆｍａｔｈｅｍａｔｉｃｓ，ＷｕｈａｎＴｒａｎｓｐｏｒｔａｔｉｏｎＵｎｉｖ...     

不对称等截面无铰圆拱的内力分析

采用弹性中心法和极坐标系计算，导出了各种外载作用下不对称等截面无铰圆拱的内力计算公式，供设计计算查用。     

RESEARCH ON HYDRODYNAMIC FORCES OF CAVITATING GRID FINS

Hydrodynamic forces and flow pattern of four kinds of cavitating grid fins with cavitation number from 2.5 to 0.25 were simulated numerically with a bubble two phase flow model embodied in the commercial CFD code Fluent 6. 0.Comparison with experimental datum showed that rules of hy drodynamic forces changing with cavitation number were coordinated with experiment, and cavitation made the ratio of lift to resistance decrease. Calculated axial force and chordal pressure center in all wetted condition or those at cavitation number less than 0. 75 agreed well with experiments. Normal force in all wetted condition was less by 20 per cent. The differences between computation and experiment in the total range of cavitation number were mainly because that the inciplent cavitation number in computation was less than that at experiment.     

鄱阳湖区土地利用变化驱动力分析

通过获得的遥感数据资料,对鄱阳湖区1988～1998年土地利用类型及土地利用类型转移进行了分析.并结合1998年之后土地利用类型的主要变化以及湖区的社会经济因素和特定的自然条件分析,发现人口、经济利益、自然灾害和政府政策是自1988年以来湖区土地利用变化的主要驱动力.     

THE PERTURBATION SOLUTIONS OF THE FLOW IN A ROTATING CURVED ANNULAR PIPE

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＡｓａｎｉｎｔｅｒｅｓｔｉｎｇｆｕｎｄａｍｅｎｔａｌｐｒｏｂｌｅｍｉｎｆｌｕｉｄｍｅｃｈｎｉｃｓ,ｔｈｅｆｌｏｗｓｉｎｒｏｔａｔｉｎｇｃｕｒｖｅｄ ｐｉｐｅｓｗｉｔｈｃｉｒｃｕｌａｒｏｒｒｅｃｔａｎｇｕｌａｒｃｒｏｓｓ ｓｅｃｔｉｏｎｓｈａｖｅｂｅｅｎｓｔｕｄｉｅｄｂｙｎｕｍｅｒｏｕｓａｕｔｈｏｒｓ .Ｌｕｄｗｉｅｇ[1] ｉｓｔｈｅｆｉｒｓｔｒｅｓｅａｒｃｈｅｒｔｏａｎａｌｙｚｅｔｈｅｆｌｏｗｉｎａｒｏｔａｔｉｎｇｃｕｒｖｅｄｒｅｃｔａｎｇｕｌａｒｄｕｃｔａｎｄｄｅｖｅｌｏ…     

ANALYTICAL SOLUTION OF WAVE-INDUCED SEEPAGE PRESSURE ACTING ON THE BASE OF BREAKWATER

The wave loads acting on a breakwater resting on seabed include not only the waveforce from the wave field around the structure but also the wave-induced seepage pressure actingon the base of breakwater.The latter is also a circumstance load which can not be neglected inengineering design.This paper presents a closed-form analytical solution of wave-induced seep-age pressure acting on the base of breakwater resting on an infinite-depth porous elastic seabed.Based on the Biot's consolidation theory,the soil deformation and the compressibility of pore wa-ter are considered.The water wave pressure on sea bottom is determined by the linear waterwave theory.The numerical results of uplifting force and moment caused by the wave-inducedseepage pressure are given and the influences of soil deformation and pore water compressibilityon the calculation results are discussed.     

止水破坏情况下的消力池护坦稳定分析

阐述止水破坏情况下消力池护坦受到脉动上举力的作用,并初步探讨止水破坏情况下消力池护坦抗浮稳定计算原则,对比止水有效及破坏情况下消力池护坦抗浮稳定安全性,提出应重视脉动上举力对消能工稳定的影响,并结合脉动上举力的产生机理及对板块的破坏形式提出消力池护坦防护措施.     

非饱和膨胀土变形规律的试验研究

通过室内膨胀土土样的膨胀试验，研究不同击实膨胀土土样在不同压力作用下膨胀变形与土样初始含水量、干密度的关系，总结膨胀上的膨胀变形规律。同时研究不同土样的膨胀力与初始含水量、干密度之间的相关性。此对研究膨胀土的变形和强度很有必要。     

A NUMERICAL STUDY ON MECHANISM OF S-STARTS OF NORTHERN PIKE （ESOX LUCIUS）

Northern pike is regarded as a specialist in swimming acceleration. The force production mechanism of northern pike,Esox lucius,during its predation S-starts was numerically studied in this article. The problem was reasonably simplified to a loose-coupling problem of fish swimming dynamics and hydrodynamics just in the swimming direction. The approach involved the simulation of the flow by solving the two-dimensional unsteady incompressible Navier-Stokes equations and decribing the fish motion dynamics based on Newton’s Second Law. Visualizations of flow fields and vortex structures were performed. The results show that the large acceleration is obtained mainly in the first undulatory cycle in which the amplitude increases. In the second cycle,a couple of vortices are generated and induce a jet. In the third cycle,the jet is strengthened by the mergence of the vortices in the same direction. Through discussing the effects of various controllable factors on the swimming performance,it is found that the actual locomotion mode of the northern pike in nature is just the best choice.     

水闸闸室化算梯形横截面上不平衡剪力的分配计算

当地弹性地基梁法计算非岩石地基的水闸底板应力时，首先要求解出不平衡剪力，当闸墩截面选择梯形时（主要是边墩），常用方法是作图法，这既有误差又繁琐。所以就此推导出一个公式，可直接求解平衡剪力。     

ANALYSIS OF BASSET FORCE OF PARTICLE MOTION IN TURBULENT FLOWS WITH SPECTRAL METHOD

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＷｉｔｈｔｈｅｗｉｄｅａｖａｉｌａｂｉｌｉｔｙｏｆｃｏｍｐｕｔａｔｉｏｎａｌｔｅ ｃｈｏｌｏｇｙ ,ｔｈｅｎｕｍｅｒｉｃａｌＬａｇｒａｎｇｉａｎｃｏｍｐｕｔａｔｉｏｎｆｏｒｆｌｏｗｓｉｎｖｏｌｖｉｎｇｄｉｓｐｅｒｓｅｄｓｏｌｉｄｐａｒｔｉｃｌｅｓｏｒａｉｒｂｕｂｂｌｅｈａｓｉｎｃｒｅａｓｅｄｄｒａｍａｔｉｃａｌｌｙｉｎｒｅｃｅｎｔｙｅａｒｓ .ＡｌｌｏｆｔｈｅｓｅｃｏｍｐｕｔａｔｉｏｎｓｕｓｕａｌｌｙｓｔａｒｔｅｄｗｉｔｈＬａｇｒａｎｇｉａｎｅｑｕａｔｉｏｎｏｆ ｐａｒｔ…     

BEARING FORCES OF EMERGENCY GATE DURING SHUTOFF

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＦｏｒａｈｙｄｒｏｐｏｗｅｒｓｔａｔｉｏｎｗｉｔｈａｌｏｎｇ ｄｉｓｔａｎｃｅｐｒｅｓｓｕｒｅｄｉｖｅｒｓｉｏｎｓｙｓｔｅｍ ,ｉｔｉｓａｌｗａｙｓｎｅｃｅｓｓａｒｙｔｏｃｏｎｓｔｒｕｃｔａｓｕｒｇｅｔａｎｋｉｎｏｒｄｅｒｔｏｒｅｄｕｃｅｅｘｃｅｓｓｉｖｅｗａｔｅｒｈａｍｍｅｒｐｒｅｓｓｕｒｅｒｅ ｓｕｌｔｅｄｉｎｔｈｅｄｉｖｅｒｓｉｏｎｓｙｓｔｅｍ [2 ,7] 　　 .Ｆｕｒｔｈｅｒｍｏｒｅ ,ｆｏｒｔｈｅｓａｆｅｔｙｏｆｔｈｅｄｏｗｎｓｔｒｅａｍｓｉｄｅｏｆｔｈｅｔａｎｋ ,ｉ…     

SPECTRAL ANALYSIS OF RANDOM WAVE UPLIFT FORCE ON A HORIZONTAL DECK

This article presents a spectral analysis of wave uplift loads on a horizontal deck.The wave uplift force spectrum on the underside of the deck is obtained.It is shown that the wave uplift force spectral density decreases with the increase of the relative clearance1/3Δh /H.The influences of different incident wave parameters,including the relative wave height1/3H /d,the relativedeck width/sB L and the relative clearance1/3Δh /Hon the dimensionless zeroth spectral moment of the uplift forces arediscussed.It is found that the zeroth spectral moment of the uplift forces increases with the increase of the relative wave height1/3H /d,and decreases with the increase of the relative clearance1/3Δh /H.A new dimensionless prediction model for the zerothspectral moment of wave uplift loads on the deck is proposed and the relationship between the wave uplift forces and the zerothspectral moment of the uplift force are obtained.     

水工隧洞设计中的几个问题的探讨

论述水工隧洞设计过程中应注意的几个问题及设计体会     

HYDRAULIC RESISTANCE OF SUBMERGED VEGETATION RELATED TO EFFECTIVE HEIGHT

Submerged vegetation has a significant impact on water flow velocity. Current investigations include the impact through adding drag resistance and increasing bottom roughness coefficient, which cannot elucidate the characters of real submerged vegetation. To evaluate the effects of submerged vegetation on water currents at different velocities, a laboratory experiment was conducted using three kinds of vegetations. The effective heights of these vegetations on varying flow velocities were evaluated. An equation describing the relationship between the normalized resistance of the submerged plants and the Reynolds number based on the plant effective height was then established and used to calculate the hydraulic resistance parameters of submerged plants in different stages of growth.     

THE NUMERICAL CALCULATION FOR THE STERN FLOW OF THREE DIMENSIONAL SURFACE SHIP WITH MULTI-PRO-PELLERS IN OPERATION

In this paper the complex structure and pattern of ship stern flow driven by multi-propellers is simulated numerically by using RANS equations with K-ε turbulence model and propeller lifting surface theory as essential research tool and coupling the computer code of ship stern flow to the computer code of propeller performance prediction through the medium of body force.A ship model with four propellers is selected as the numerical example.Detailed computational results are presented graphically and the qualitative and quantitative analysis is made. Finally,the comparison between the calculated result and the available experimental data is made.The agreement between them is satisfactory.     

HYDRODYNAMICS OF FRACTAL FLOCS DURING SETTLING

The settling and hydrodynamic properties of 3-D fractal flocs in quiescent water are investigated with a numerical model based on the Lattice Boltzmann Method (LBM), with considering the settling velocity, hydrodynamic drag force and infra-floc flow. The comparisons of floc settling velocities and effective densities indicate that the numerical results present good agreements with observations in field and at laboratory. The results show that the drag force FD increases with the floc size df according to the relationship FD∝df3. Moreover, the intra-floc flow field and movement of the pore water provide a better understanding of the intra-floc flow from the microscopic viewpoint. The results also indicate that the lattice Boltzmann method is a promising approach to reveal the mechanisms of the flocculation in aquatic environments.