EXPERIMENTAL RESEARCH OF EQUILIBRIUM AND NONEQUILIBRIUM DYNAMIC ADSORPTION OF Cd~(++) IN SOIL--EFFECT OF DIFFERENT ACIDITIES AND SATURATION

This paper studies water and solute transport in soil. It mainly deals with theadsorption behavior of heavy metal Cd~(++) in soil at different P~H values and the dynamic charac-ters of adsorption process in unsaturated state. Through theoretical analysis and experimental re-search, the adsorption isotherm and the equations of dynamic adsorption in saturated and unsatu-rated states are proposed.     

THE PERFORMANCES OF HIGH PRESSURE JET OF PURE WATER AND POLYMER SOLUTION WITH CONICAL NOZZLE

In this paper, the effects of polymer additives and nozzle shape on the proper-ties of high pressure water jet discharging into the air are investigated by theoryand experiments. Criteria of judging the jet quality are put forward. And, a methodthat can be used in analysing the fluid flow within the nozzle is developed. Then,the calculated results are compared with the experiments that we carried out;it is shown that the degree of agreement between the two is good. At last, themechanism to improve on the jet quality with polymer additives is discussed.     

PROBABILITY DISTRIBUTION OF IN-LINE WAVE FORCES ON A PILE IN IRREGULAR WAVES

The probability distribution of in-line wave forces on a pile can bemathematically summed up to that of a theory and the assumption of wave period being constantare used and the above probability distribution is simplified to that of a single dimentsionfunction.The probability density functions of the peak values of total wave forces on a wholevertical pile in irregular waves are derived from that of wave height which is the Rayleighdistribution(deep water wave)or the Kerohovski distribution(shallow water waves)on the baseof the Morison Equation.The identification with experimental data shows that suchsimplification is successful.These distributions are compared with Weibull distribution andRayleigh distribution and the result shows that the shallow water distribution of wave forcesobtained here is the best one and can be used in practice.     

A NEW NUMERICAL MODEL FOR THREE DIMENSIONAL SURFACE WATER FLOWS

A three dimensional numerical model based on the Reynolds equations is presented that can be used to predictthe surface water flow in open channels.The model uses a computational mesh that conforms to the free water sur-face and the bottom of the channel so that the accuracy of boundary condition application,code complexity,and e-conomy could be enhanced.The k-ε turbulence model is used to estimate the eddy viscosity coefficient.Instead ofusing the“rigid-lid”approximation a 2-D equation derived from integrating the continuity equation over the totaldepth is adopted to determine the elevation of the free water surface.A new algorithm is presented based on theconventional SIMPLE procedure.The block correction technique is employed to enhance rate of convergence.The model presented is applied to a bottom discharge into a rectangular straight channel for three dimensionalphenomena to obtain the free water surface configuration,velocities and pressure.The computed results are ingood agreement with the previous experimental values.     

THE NEW ENTROPY FORMULA FOR OPTIMAL DESIGN OF WATER DISTRIBUTION SYSTEMS

A new formula of entropy for optimal design of water distribution systems is developed in the paper. The value of entropy obtained by the formula can be used to specify the interior connectivity in system and .reliability of providing water for demanded nodes. Based on the formula, an entropy-optimization model is developed. Two networks are used as the examples of optimal design. The optimal results shows its obvious advantage of litter computer time. Therefore, the entropy-optimization model has more practical significance.     

RADICAL FLOW IN POROUS MEDIA WITH DISPERSION AND ADSORPTION

The radical transport of chemical concentration in porous media with dispersion and adsorption was studied in this paper. Using Langmuir‘s adsorption model, the numeri cal equation of concentration transport was derived. The flows with and without adsorption were simulated and analyzed. Comparison of the obtained solution with the known analytical solution for flow without adsorption shows the presented numerical method is correct and effective, which can be used in reservoir engineering     

A NOVEL 3-D MODEL FOR THE WATER CRESTING IN HORIZONTAL WELLS

In the presence of bottom water, a drop in the reservoir pressure due to fluid production causes the aquifer water to expand and to flow into the reservoir. Therefore, hydrocarbon production from a well is limited by the critical flow rate. The main purpose of this study is to investigate the breakthrough time and the critical rate by using a novel 3-D horizontal well model. Based on the hypothesis that the horizontal well is located in any position of a circular reservoir with no-flow boundary on the top of the reservoir and constant pressure boundary at the bottom, the horizontal well has been regarded as an infinite conductivity line sink and then a 3-D steady-state flow model of the horizontal well is set up. A point sink pressure solution can be obtained with the Fourier transform. The result of the pressure distribution of the uniform flux horizontal well can be presented by means of the principle of superposition. According to the stable water cresting theory, this study confirms the stable height of water cresting and the critical rate. Meanwhile, it can re-confirm the breakthrough time at a specific rate. The output of a comparison between this 3-D model and the reservoir numerical simulator （Eclipse） shows the method presented here can be applied to investigate the behavior of a water cresting and to predict the breakthrough time at the bottom water driver reservoir.     

PROBLEM OF SUDDENLY STARTING OF A VERTICAL PLATE IN DEEP WATER

In this paper, we apply Lagrangian method and analyse the problem of suddenly starting of a verti-cal plate in deep water. The solutions to the problem are obtained by means of conformal mappingand Green's function. Explicit expressions of the wave shape and the pressure coefficient areobtained. The pressure coefficient has a weak singularity at the free surface. It is possiblethat Lagrangian method may be applied to analyse more complex problem of the transient wave.     

THE MOTION OF A BUBBLE IN WAVES

The motion of a single spherical bubble due to buoyancy in the ideal fluid with waves is studied in this article. Assuming that the bubble has no effect on the wave field, equations of a bubble motion are attained. The equations are solved. It is found that the nonlinear effect increases with the increase of the bubble radius. Since the difference between the frequencies of gravity waves and the eigenfrequency of bubbles is great for small bubbles, their oscillations can not be coupled. During the rising of a bubble, the oscillation of the bubble decays very fast, so it can be ignored. The rising time and the motion orbit are given. When the wave is high and the bubble is small, the spiral orbit may appear.     

RELATIONSHIP AMONG EVAPORATION FLUX OF GROUNDWATER, DEPTH OF WATER TABLE AND NEGATIVE PRESSURE HEAD IN BARE SOIL

1.　 INTRODUCTIONThe crisis of water resources is a global problem.Compared with other countries,Chi-na relatively falls shortof water resources.The amount of water resources per capita is justone fourth as the world average value. The distribution of water resources is outof balance.81 % ofthe water resources is concentrated in the reach of the Yangtse River and the south-ern areas of China,while only1 9% is in the areas of the north to the Yangtse River,inwhich the population is4 5.3%…     

INFLUENCE OF LONG AND DEEPLY-BURIED DIVERSION TUNNELS ON THE WATER TEMPERATURE

A 3-D temperature model for diversion tunnel was developed by combining/e-e model and energy transport equation. The actual geometry data of the tunnel was used to construct a three-dimensional computational domain including the concrete lining. As the interaction between temperature and velocity fields can be taken into account, the model can be employed to accurately simulate the temperature and velocity field. The model was validated with the field data observed in the diversion tunnel of the Nanya River. The water temperature of the diversion tunnel of the Second Jinping Cascade Hydropower Station to be built was predicted. It is shown that the temperature increase is not observable due to the large diameter of the tunnel, the big flow rate and the short contact time. The result can provide scientific foundation or reference for the design of hydropower station, and protection strategy of aquatic organisms and aquatic ecosystem.     

DISTRIBUTIONS OF FLOW RATE AND CONTAMINANT IN RIVER OR CHANNEL DIVERSION

Based on numerical modelling for two-dimensional flow in which the density ofeffluent is different from that of environment,the flow and concentration fields are couplinglysolved.Through numerical integration the flow rate and contaminant distributions with differentangles and different momentum of effluent can be obtained.The results given in this paper couldbe a base for quantitative estimation in hydraulic engineering design and assessment and planningof water quality.     

THE GENERATION OF CNOIDAL WAVE IN A WAVE FLUME

The method of cnoidal wave generation in a wave flume is studied in this paper.According to the wave equa-tion in shallow water,the wave paddle motion equation for given wave parameters and water depth is derived.Thecontrolling signal for driving wavemaker can be converted from its solution,and high wave height shallow waterwaves can be generated.The experiment results show that,the parameters of the wave generated are very close tothe required ones in a certain distance in front of the paddle of the wavemaker.     

NUMERICAL RESEARCH ON WATER GUIDE BEARING OF HYDRO-GENERATOR UNIT USING FINITE VOLUME METHOD

With the consideration of the geometry of tilting pad journal bearing, a new form of the Reynolds equation was derived in this article. The film thickness, the squeeze motion of the journal and the rotation motion of the pad were explicitly contained in the equation. Based on this equation, together with the equilibrium equation of pad pivot, the water guide bearing used in the Gezhouba 10 F hydro-generator unit was numerically researched. The new Reynolds equation for the lubricating film was solved using Finite Volume (FV) discretization, Successive Over-Relaxation (SOR) iteration method and C code are included. According to the numerical solution, and the stability of the film and the influences of the film thickness, the journal squeeze effect and the pad rotation effect on film force were discussed. The results indicate that the squeeze effect can not be neglected, although the rotation effect is negligible for both low-speed and high-speed bearings, so the computing time could be greatly reduced.     

HYDRODYNAMIC BEHAVIOR OF FPSO UNDER VARIUS LOADING IN SURVIVAL STORMS IN SHALLOW WATER

The motion performance and clearance between the hull and seabed of a FPSO (Floating, Production, Storage and Offloading units) in survival storm conditions are closely related to its safety during the operation in shallow water. As an example the behavior of a 160 kDWT FPSO with single point mooring system in shallow water was investigated in this paper. Calculation for the FPSO is made based on the 3-D linear potential flow theory and time-domain numerical simulation method and corresponding model test is carried out in the wave basin at Shanghai Jiaotong University. Both the calculated and experimental results indicate that the heave, roll and pitch motions of FPSO become lazy with the increase of the draft. And the fully loaded FPSO in survival storm touched seabed few times. Therefore, it is concluded that the FPSO should be less loaded than that in the fully loaded condition when the survival storm is coming.     

NUMERICAL STUDY OF SQUARE-STERN SHIP WAVE IN SHALLOW WATER

This paper employed shallow water equations with moving pressure to calculate water waves generated by a square-stern ship in shallow water. The moving ship is considered as moving pressure on free surface. The finite element method with moving grids is used to solve the shallow water equations based on wave equation model [3]. A non-reflection boundary condition [5]is imposed on open boundaries surrounding the ship. 3-D surface elevations, depth-averaged horizontal velocities are presented. The numerical solutions are physically reasonable. It is found that wave resistance coefficients, draftchange and pitch angle vary rapidly in neighborhood of critical flow (Fh=u/ gh= 0. 9 -1. 1). The numerical results also indicate that the wave resistance coefficients, draft change and pitch angle of square-stern ship are larger than those of sharp-stern ship with the same hull structure at the same speed.     

WATER HAMMER ANALYSIS OF WATER FEEDING SYSTEM IN COAL FIRED POWER STATION AND ITS INFLUENCE ON THE SAFETY OF OPERATION

In the coal fired power station, the regulation of the load or the sudden stop operation of the unit in accident may result in water hammer, which would have critical influence on the safe operation of the unit. In this paper, the analysis of the water dynamic characters and the calculation of the pressure increment are shown, when the water hammer is produced in the system .     

NUMERICAL SIMULATION OF ROCK BREAKING MECHANISM WITH HIGH-PRESSURE WATER JET

Based on the analysis of experimental results.the rock damage model and the damage coupling model suitable for the whole rock breaking process with water jet were established with continuous damage mechanics and micro damage mechanics, and the numerical method was developed with continuum mechanics and the FEM theory. The rock breaking mechanism with water jet was studied systematically with numerical simulation for the first time in the field of water-jet rock breaking. The numerical results agree with the experimental ones which shows that the presented method is reasonable and can reflect the reality of water-jet rock breaking. The conclusion can be applied in practice.     

A LINEAR HYBRID MODEL OF MSE AND BEM FOR FLOATING STRUCTURES IN COASTAL ZONES

1. INTRODUCTION In coastal zones, wave propagation in water is considerably affected by the topography of the sea bottom, which may result in changes in the direction and shape of the waves and may cause redistribution of their energy in space, etc. Waves may also lose a certain amount of energy by wavebreaking or by other forms of dissipation. It can be easily seen that wave propagation in shallow waters is a very complicated process resulting from various mechanisms. The dominant mechan…     

RIABOUCHINSKY MODEL AND DEEP CLOSURES OF THE CAVITY AFTER VERTICAL WATER ENTRY OF A SPHERE

On the basis of [5] and [7], the process of surface closure and deep closures of a cavity developed bythe vertical entry of a body into water at a high Froude number is investigated, A modifiedRiabouchinsky model which is commonly applied to cases of steady cavity flows is used for this purporse.Agreement between experi mental and numerical results seems to be satisfactory.