A NEW TURBULENCE MODULATION IN SECOND-ORDER MOMENT TWO-PHASE MODEL AND ITS APPLICATION TO HORIZONTAL CHANNEL

A new second-order moment two- phase turbulence model accounting for particle wake effect was established and used to simulate gas-particle flow in a horizontal channel for different values of wall roughness. The results show that compared with the model without considering the particle wake effect, the present model gives simulation results agreeing much better with the experimental results for the gas turbulence modulation, but the predicted results for particle motion with the two kinds of models are quite close.     

NUMERICAL SIMULATION FOR THE STEPPED SPILLWAY OVERFLOW WITH TURBULENCE MODEL

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｓｔｅｐｐｅｄｓｐｉｌｌｗａｙｈａｄｂｅｅｎｕｓｅｄａｔｔｈｅｂｅｇｉｎｎｉｎｇｏｆｔｗｅｎｔｙｃｅｎｔｕｒｙ[1 ] .Ｉｎ 1 971 ,Ｅｓｓｅｒｙｅｔａｌ.[2 ] ｃｏｎｄｕｃｔｅｄａｍｏｄｅｌｔｅｓｔｆｏｒｔｈｅｄｅｓｉｇｎｏｆ     

A NEW DEPTH-AVERAGED ALGEBRAIC STRESS MODEL AND ITS VERIFICATION TEST

1.mThonvrmNTurbulencemodelshavefoundtheirwideapplicationsinscienceandtechnolOgyrelaedtofiuidflOw.UptonowvariouskindsOfturbulencemedelsaredeveloPedincludingtheone-equatbomodel(Bradshaw,P.etal.,1967),thetwo-equatbomedel(SPalding,l969),themuliple-equationmodel(Davidov,1961),thealgebraicstressmodl(Launder,etal.,1972)andsoon.Amongthesemodels,thetwo-equationkBmodeliswidelytestedandued.Thealgebraicstressmodelsareintermediatebetweensecond-ordercforuerschemesusingtranSPOrtequatbosfortheindividual…     

THREE-DIMENSIONAL TURBULENCE NUMERICAL SIMULATION OF A STEPPED SPILLWAY OVERFLOW

In this paper, the κ-ε two-equation turbulence model was used to simulate the three-dimensional turbulent flow of the stepped spillway at the Yubeishan reservoir. In order to solve the curved free water surface and to handle the complex boundary conditions, the fractional Volume Of Fluid (VOF) model that is applicable to the solution of the stratified two-phase flow was intorduced to the κ-ε turbulence model and the unstructured grid was used for the discretization of the irregular simulation domain. By these methods, the turbulent flow field of the stepped spillway was simulated successfully.The location of the free surface along the spillway, the magnitude and distribution of the velocity, the pressure distribution on the step surface, the turbulence kinetic energy and turbulence dissipation rate were obtained by simulation. The changes and distributions of these characteristics along the width of the spillway were also obtained. The energy dissipation ratio of the stepped spillway was calculated according to the upstream and downstream water depth and velocities.     

THREE-DIMENSIONAL TURBULENCE NUMERICAL SIMULATION OF A STEPPED SPILLWAY OVERFLOW

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅａｐｐｌｉｃａｔｉｏｎｏｆｔｈｅｓｔｅｐｐｅｄｓｐｉｌｌｗａｙｈａｓｈａｄａｌｏｎｇｈｉｓｔｏｒｙ .Ｔｈｅ ｐｈｙｓｉｃａｌｍｏｄｅｌｔｅｓｔｓｔｕｄｙｏｆｔｈｅｓｔｅｐｐｅｄｓｐｉｌｌｗａｙｈａｓｂｅｅｎ ｐｅｒｆｏｒｍ     

APPLICATION OF A MODIFIED QUICK SCHEME TO DEPTHAVERAGED k-( TURBULENCE MODEL BASED ON UNSTRUCTURED GRIDS

The modified QUICK scheme on unstructured grid was used to improve the advection flux approximation, and the depth-averaged turbulence model with the scheme based on FVM by SIMPLE series algorithm was established and applied to spur-dike flow computation. In this model, the over-relaxed approach was adopted to estimate the diffusion flux in view of its advantages in reducing errors and sustaining numerical stability usually encountered in non-orthogonal meshes. Two spur-dike cases with different defection angles (90oand 135o) were analyzed to validate the model. Computed results show that the predicted velocities and recirculation lengths are in good agreement with the observed data. Moreover, the computations on structured and unstructured grids were compared in terms of the approximately equivalent grid numbers. It can be concluded that the precision with unstructured grids is higher than that with structured grids in spite that the CPU time required is slightly more with unstructured grids. Thus, it is significant to apply the method to numerical simulation of practical hydraulic engineering.     

STUDY OF THE MATHEMATICAL MODEL FOR RIVER CLOSURE USING BI-EMBANKMENT

This paper is concerned with a mathematical model for river closure using two embankments. Some novel techniques of computational fluid dynamics and the two equation (k-ε)turbulent model are used to solve the shallow water equations in curvilinear coordinates; and the technique of moving boundary is used to deal with the river bed exposed to water surface. Comparison between computed and experimental data shows a satisfactory agreement. The mathematical model can be employed to accurately simulate the characteristics for the studied flows and could find more applications in hydraulic engineering.     

NUMERICAL SIMULATION OF MOVING SCOUR BOUNDARY AND TURBULENCE FLOW AROUND SUBMARINE PIPELINES

A two dimensional vertical mathematical model is proposed in this paper for simulating the equilibrium profile of local scour around submarine pipelines. The current model is composed of a new k-ε turbulence model, fitting moving boundary with pre-meshed grid lines and incipient criterion of shear stress for sediments. Employing the proposed model, an instance is carried out numerically and compared with experiments. The calculation results agree well with the experiments. It shows that the improved two equation turbulence model, adopted in this paper is appropriate to simulating the turbulent flow ficld around submarine pipelines, fitting moving boundary with pre-mcshed grid lines method is efficient for moving boundary problems in a multiply connected domain and the stability evaluation method for seabed with critical shear stress based on log-wall law is a reliable choice.     

THE TURBULENT MODEL OF LIQUID-PARTICLE FLOWS AND ITS APPLICATION TO NUMERICAL PREDICTION OF OIL POLLUTION

Simulation of particle turbulent transport in present mathematical models of two-phase turbulent flows is algebraic model based on local following theory. The predicted results bythese models are not consistent with that of experiments available. The motion of two-phase flowis described by a unified model of multi-fluid in this paper. The two-fluid turbulent model oftwo-phase flow based on k-e equations for particles and fluid, and corresponding numerical thch-nique are both developed. The proposed model and the numerical technique are successfully em-ployed to numerical modelling for oil-water two-phase turbulent recirculating flow.     

SIMPLIFIED MODEL AND ITS APPLICATION FOR WAVEMAKING INDUCED BY EXPLOSION

ＳＩＭＰＬＩＦＩＥＤＭＯＤＥＬＡＮＤＩＴＳＡＰＰＬＩＣＡＴＩＯＮＦＯＲＷＡＶＥＭＡＫＩＮＧＩＮＤＵＣＥＤＢＹＥＸＰＬＯＳＩＯＮ￥ＳｈｅｎＧｕｏ－ｇｕａｎｇ；ＬｉＤｅ－ｊｕｎ（ＴａｉｎｊｉｎＵｎｉｖｅｒｓｉｔｙ，Ｔｉａｎｊｉｎ３０００７２，Ｐ．Ｒ．Ｃｈ...     

A TURBULENCE MODEL FOR VARYING DENSITY FLOW IN GENERAL CURVILINEAR COORDINATES

ＡＴＵＲＢＵＬＥＮＣＥＭＯＤＥＬＦＯＲＶＡＲＹＩＮＧＤＥＮＳＩＴＹＦＬＯＷＩＮＧＥＮＥＲＡＬＣＵＲＶＩＬＩＮＥＡＲＣＯＯＲＤＩＮＡＴＥＳＺｈｅｎｇＢａｎｇ－ｍｉｎｇ；ＹａｎｇＸｉａｏ－ｔｉｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＲｉｖｅｒＥｎｇｉｎｅｅｒｉｎｇ...     

A SECOND-ORDER MOMENT TURBULENCE MODEL FOR POWER LAW FLUID WITH PARTICLES

The USM-θ model of power law fluid for dense two-phase turbulent flow was developed, which combines the unified second-order moment model for two-phase turbulence with the particle kinetic theory for the inter-particle collision. This model was used to simulate the turbulent flow of power law fluid single-phase in pipe. It is shown that the USM ? θ model has better prediction result than the k f ? ε f?kp?εp?θ model. The USM ? θ model was then used to simulate the dense two-phase turbulent up flow of power law fluid with particles. With the increase of the flow exponent, the velocities of power law fluid and particles increase near the pipe centre. Comparison between the two-phase flow of power law fluid-particle and of liquid-particle indicates that the axial fluctuation velocity of fluid phase and particle phase in liquid-particle two-phase flow is smaller than that in the power law fluid two-phase flow, but the two-phase velocities of power law fluid-particle and liquid-particle are close to each other.     

模糊控制的预测模型及其应用

本文以青铜峡大坝变形观测资料为例 ,依据模糊控制理论 ,研究了用模糊聚类分析法建立复杂结构混凝土坝变形的预测模型。这对综合分析和评价复杂结构混凝土坝的变形性态具有较大的实用价值     

STOCHASTIC ANALYSIS MODEL FOR RIVER WATER QUALITY AND ITS APPLICATION

１．　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｗａｔｅｒｅｎｖｉｒｏｎｍｅｎｔｉｍｐａｃｔｓｔａｔｅｍｅｎｔａｎｄｗａｔｅｒｑｕａｌｉｔｙｓｙｓｔｅｍａｎａｌｙｓｉｓａｎｄｐｌａｎｎｉｎｇ，ｗａｔｅｒｑｕａｌｉｔｙｍｏｄｅｌｓａｒｅｗｉｄｅｌｙｕｓｅｄｔｏｓｉｍｕｌａｔｅｔｈｅｐｒｏｃｅｓｓｏｆｐｈｙｓｉｃａｌ，ｃｈｅｍｉｃａｌａｎｄｂｉｏｌｏｇｉｃａｌｃｈａｎｇｅｓｏｆｃｏｎｔａｍｉｎａｎｔｉｎｗａｔｅｒｂｏｄｙ．Ｇｅｎｅｒａｌｌｙｔｈｅｗａｔｅｒｑｕａｌｉｔｙｍｏｄｅｌｓｃａｎｂｅｃｌａｓｓｉｆｉｅ…     

STUDY AND APPLICATION OF STEADY FLOW AND UNSTEADY FLOW MATHEMATICAL MODEL FOR CHANNEL NETWORKS

Based on the Preissmann implicit scheme for the one-dimensional Saint-Venant equation, the mathematical model for one-dimensional river networks and canal networks was developed and the key issues on the model were expatiated particularly in this article. This model applies the method of three-steps solution for channel-junction-channel to simulate the river networks, and the Gauss elimination method was used to calculate the sparse matrix. This model was applied to simulate the tree-type irrigation canal networks, complex looped channel networks and the Lower Columbia Slough networks. The results of water level and discharge agree with the data from the Adlul and field data. The model is proved to be robust for simulating unsteady flows in river networks with various degrees of complex structure. The calculated results show that this model is useful for engineering applications in complicated river networks. Future research was recommended to focus on setting up ecological numerical model of water quality in river networks and canal networks.     

A NUMERICAL MODEL FOR 3-D FLOW IN OPEN CHANNELS

A 3-D model based on the Reynolds equations with closed k-ε turbulence model ispresented in this paper,which can be used to predict surface water flow in open channels.In-stead of the“rigid lid”approximation,the solution of the free surface equation is implemented inthe velocity-pressure iterative procedure on the basis of the conventional SIMPLE method.Thismodel was used to compute the flow in rectangular channels with trenches dredged across the bot-tom.The velocity,eddy viscosity coefficient,turbulent shear stress,turbulent kinetic energyand elevation of the free surface over the trenches dredged in the main channel,can be obtained.The computed results are in good agreement with existing experimentaing data.     

基于开关控制策略的厂内经济运行模型及应用

通过划分机组的约束限制条件为安全运行区和非安全运行区，提出了一 种基于开关控制策略的厂内经济运行模型。该模型有效地反映了机组的运行状态，并且保证 了设备的可利用率，较好地解决了影响水轮机效率、使用寿命、甚至可能危及电站运行安全 的机组不可运行区等约束限制问题。算例表明，该方法是有效的。     

COUPLING DISTINCT AND CONTINUOUS MEDIUM MODEL FOR FLOW ANALYSIS IN A FRACTURED ROCK MASS AND ITS APPLICATION

Fractures in a rock mass can be divided into dominant fracture system and network fracture system. An approach for the analysis of three dimensional ground water flow in a fractured rock mass is presented, in which flow in the dominant fracture system is described by a distinct medium model while flow in the network fracture system plus rock matrices (if considered) is described by a continuous medium model, and the two models are coupled by hydraulic head and flux. The coupling model facilitates to calculate one-by-one the fluid flow in the dominant fractures which are functioned as the major water transmission conduits, and it avoids unnecessary calculating fluid flow in individual network fractures which are numerous in number. In this way, the method can be applied to a large-sized calculation domain. In addition, a method of using network geometry data to calculate its equivalent porous permeability is presented in the paper, and the model implementation of water source and sink such as the pumping     

SIMULATION OF STRONG TURBULENCE FLOW WITH FREE SURFACE INCLUDING THE EFFECTS OF STREAMLINE CURVATURE

This paper is concerned with a mathematical model for two-dimensional strong turbulence flow with free surface including the effects of streamline curvature in orthogonal curvilinear coordinate system, with which the characteristics of the turbulence flow field on the ogee spillway was numerical simulated. In the numerical simulation, the flow control equations in orthogonal curvilinear coordinate system were discretized by the finite volume method, the physical parameters（ P, U,V,K,ε,γt , etc. ） were arranged on a staggered grid, the discretized equations were solved with the SIMPLEC method, and the complex free surface was dealt with VOF method. The computed results show that the velocity fields, pressure field, shear stress distribution and kinetic energy of turbulent flow on the ogee spillway are in agreement with experimental data. This confirms that the model can be used for numerieal simulation of the turbulence flow on ogee spillway.     

THE APPLICATIONS AND STUDY OF NUMERICAL SIMULATION OF TURBULENCE FLOW WITH FREE SURFACE IN HYDRAULIC SPILL WAYS STRUCTURE

The turbulence flow Free Surface has important applications in hydraulic spillways structure,such as the hydraulic jump,energy dissipation flow etc.This is being considered as very complicated flow,and has not yet been solved quite well by numerical method. In this paper,a Large-scale computational software package are developed for numerical laboratory of hydraulic spillway structure.Some methods,such as turbulence model, free surface and irregular boundary treating techniques,scientific computer visualization are put forward and performed.