HAGEN POISEUILLE FLOW OF A GRANULAR MATERIAL IN A CYLINDER

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｒｅｃｅｎｔｙｅａｒｓ ,ｓｔｕｄｙｉｎｇｔｈｅｍｏｔｉｏｎｏｆｆｉｎｅｇｒａｎｕ ｌａｒｍａｔｅｒｉａｌｓｉｓａｎｅｗｔｏｐｉｃｉｎｆｌｕｉｄｍｅｃｈａｎｉｃｓ.Ａｌｔｈｏｕｇｈｇｒａｎｕｌａｒｍａｔｅｒｉａｌｓｄｏｅｓｎｏｔｂｅｌｏｎｇｔｏｒｅａｌｆｌｕｉｄ ,ｔｈｅｍｅｔｈｏｄｓｏｆｓｔｕｄｙｉｎｇ ｇｒａｎｕｌａｒｍａｔｅｒｉａｌｓａｒｅｓｉｍｉｌａｒｔｏｔｈｏｓｅｏｆｆｌｕｉｄ ｓｔｕｄｙｉｎｇ .Ｓｏｍａｎｙｍｅｔｈｏｄｓｏｆｆｌｕｉｄ ｓｔｕｄｙｉｎｇｈａｖｅ…     

NUMERICAL SIMULATION OF BUBBLE FLOW INTERACTIONS

Bubble flow interaction can be important in many practical engineering applications. For instance, cavitation is a problem of interaction between nuclei and local pressure field variations including turbulent oscillations and large scale pressure variations. Various types of behaviours fundamentally depend on the relative sizes of the nuclei and the length scales of the pressure variations as well as the relative importance of bubble natural periods of oscillation and the characteristic time of the field pressure variations. Similarly, bubbles can significantly affect the performance of lifting devices or propulsors. We present here some fundamental numerical studies of bubble dynamics and deformation, then a practical method using a multi-bubble Surface Averaged Pressure (DF-Multi-SAP©) to simulate cavitation inception and scaling, and connect this with more precise 3-D simulations. This same method is then extended to the study of two-way coupling between a viscous compressible flow and a bubble population in the flow field.     

THE NUMERICAL COMPUTATION OF TURBULENT FLOW IN TEE-JUNCTION

A numerical model for calculating the turbulent flow in tee-junction is given in thispaper.The calculations are performed using a finite-difference procedure,and turbulence is ac-counted for by using a two-equation k-ε model of turbulence.Results,consisting of mean veloci-ty profiles and pressure losses due to the junction,have been obtained,and show that the flowsituation in tee-junction is very complex.The computed results agree closely with the experimen-tal data and validate that the present model is reasonable and the numerical calculations are suc-cessful.     

NUMERICAL SIMULATION OF THE TURBULENT FLOW IN ROTATING DUCT

l.INrnODUCT1oNFlowintherotatingductisakindofphenomenonofturbulentflow,whichisoftenfoundintheengineeringapplications,suchasinthecentrifugalcompressor,centrifugalpumpandturbomachinery.Theinvestigationontheductflowisveryimportantfortheen-gineeringpracticejustasthequalityofflowintheductmakesbiginfluenceontheperfor-manceandefficiencyofthemachine.Thestudyontheflowintherotatingductbeganin6os'.JohnsonL1jmeasuredthevelocityofthemainstreaminthetwodimensionalrotatingduct.Comparedwiththeflowinthestati…     

NUMERICAL SIMULATION OF THE FLOW PATTERNS OF YUQIAO RESERVOIR

In this paper the slot method is used in the computation of 2-dimensional flow withtransient boundary.The slot located inside the computation zone is placed in each space grid,parallel to both X and Y axes.Combined with the operator splitting method,the numerical simu-lation of the flow patterns of Yuqiao Reservior is made.The calculated results are in good agree-ment with observed data.     

NUMERICAL FLOW VISUALIZATION OF A MIXING LAYER

The Kelvin-Helmhotz rollup of three-dimensional time-developing mixing layers is simulated numerically. Dye lines or fluid interfaces, often visualized in experiments, are presented by computing the passive scalar at high Peclet number. The scalar contours reveal the mushroom-shaped streaklines observed in many experiments [l]and uncover by far more exquisite structures beyond experimental observations. The hydric bubbles released at a constant time interval are also simulated numerically. To help understand the visualization results, we analyze the behavior of the coherent structures, such as the streamwise ribs and the spanwise rollers. A comparison between the vortical structure and the passive scalar contours indicates that the wrapping by the vortices largely dominates the evolution of the passive scalar.     

NUMERICAL MODELING OF UNSTEADY SEPARATING FLOW AND ITS EXPERIMENT VERIFICATION

A simulation of unsteady separating flow in an expanding flume is presented inthis paper.The numerical modeling is based on a general horizontal 2-D mathematical model ofunsteady flow.It is verified that the flow pattern,whirlpool length and maximum reversalvelocity reasonably agree with the data from flume tests and this result could be an additionalproof for the validity of the earlier developed mathematical model.     

NUMERICAL SIMULATION OF DISCONTINUOUS FLOW IN CIRCULAR CONDUITS

ＮＵＭＥＲＩＣＡＬ　ＳＩＭＵＬＡＴＩＯＮ　ＯＦ　ＤＩＳＣＯＮＴＩＮＵＯＵＳ　ＦＬＯＷ　ＩＮ　ＣＩＲＣＵＬＡＲ　ＣＯＮＤＵＩＴＳＮＵＭＥＲＩＣＡＬＳＩＭＵＬＡＴＩＯＮＯＦＤＩＳＣＯＮＴＩＮＵＯＵＳＦＬＯＷＩＮＣＩＲＣＵＬＡＲＣＯＮＤＵＩＴＳ￥ＭａｏＺｅ...     

NUMERICAL SOLUTION OF INCOMPRESSIBLE VISCOUS FLOW OVER AEROFOIL WITH H-TYPE GRID

The numerical solution of incompressible viscous flow over an aerofoil is obtainedby H-type grids and a special difference scheme. The method of mass flux corection is introducedwith success in order to accelerate convergence in iteration of velocity and pressure calculation.     

AN EXPERIMENTAL AND NUMERICAL INVESTIGATION OF THE STARTING FLOW OF A UNIFORMLY ACCELERATING CIRCULAR CYLIINDER

The starting flow around a uniformly accelerated circular cylinder is investigatedby flow visualization techncque and solving N-S equations numerically in detail.The results ofthe starting flow are similar with those of the impulsively started one.At lower Re_α,numbers the“phenomenon a”is revealed;the“phenomenon β”appears at higher Re_α numbers,but withonly one secondary vortex.At the early stage of the starting vortex formation,the flow islaminar;at the later stage,the flow transforms into turbulent flow.The velocity distribution inthe flow field is measured with the multiwires installment.The calculational results are comparedwith the results of experiment,and both are in agreement with each other.     

NUMERICAL SIMULATION OF THE EFFECT OF FILLET FORMS ON APPENDAGE－BODY JUNCTION FLOW

ＮＵＭＥＲＩＣＡＬＳＩＭＵＬＡＴＩＯＮＯＦＴＨＥＥＦＦＥＣＴＯＦＦＩＬＬＥＴＦＯＲＭＳＯＮＡＰＰＥＮＤＡＧＥ－ＢＯＤＹＪＵＮＣＴＩＯＮＦＬＯＷＬｉＤｉｎｇ；ＺｈｏｕＬｉａｎ－ｄｉ（ＣｈｉｎａＳｈｉｐＳｃｉｅｎｔｉｆｉｃＲｅｓｅａｒｃｈＣｅｎｔｅｒＰ．...     

NUMERICAL MODEL FOR DYNAMIC SIMULATION OF TRAFFIC FLOW

ＮＵＭＥＲＩＣＡＬＭＯＤＥＬＦＯＲＤＹＮＡＭＩＣＳＩＭＵＬＡＴＩＯＮＯＦＴＲＡＦＦＩＣＦＬＯＷＷｕＺｈｅｎｇ；ＺｅｎｇＬｉ－ｎｏｎｇ（ＤｅｐａｒｔｍｅｎｔＡｐｐｌｉｅｄＭｅｃｈａｎｉｃｓ，ＦｕｄａｎＵｎｉｖｅｒｓｉｔｙ，Ｓｈａｇｈａｉ２００４３３，Ｐ...     

NUMERICAL INVESTIGATION ON FLOW CHARACTERISTICS IN RIBBED BEND

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｇａｓ ｐａｒｔｉｃｌｅｆｌｏｗｉｎｃｕｒｖｅｄｄｕｃｔｓｈａｖｅｂｅｅｎｗｉｄｅｌｙａｐｐｌｉｅｄｉｎｅｎｇｉｎｅｅｒｉｎｇ .Ｒｅｓｅａｒｃｈ[2 ] ｓｈｏｗｓｔｈａｔｔｈｅｅｒｏｓｉｏｎｅｆｆｉｃｉｅｎｃｙｏｆｂｅｎｄｉｓ 5 0ｔｉｍｅｓｈｉｇｈｅｒｔｈａｎｔｈａｔｏｆｓｔｒａｉｇｈｔｐｉｐｅ .Ｔｈｅｒｅｆｏｒｅ ,ｉｍｐｒｏｖｉｎｇｔｈｅａｂｉｌｉｔｙｏｆｂｅｎｄｅｒｏｓｉｏｎｐｒｏｔｅｃｔｉｏｎｉｓａｎｕｒｇｅｎｔｔａｓｋ .Ｔｈｅｐｒｅｖｉｏｕｓｒｅｓｅａｒｃ…     

NUMERICAL SIMULATION OF SKIMMING FLOW OVER MILD STEPPED CHANNEL

1. INTRODUCTION The stepped channel/spillway finds its extensiveapplications in hydraulic and environmentalengineering, which is used to dissipate the energy ofreleased flood and also to be a landscape structure.Flow over the stepped channel/spillway is a…     

A BOUNDARY INTEGRAL EQUATION AND ITS NUMERICAL SOLUTION OF POTENTIAL FLOW AROUND SURFACE-IRREGULA-RITIES

In this paper,using complex functional theory,the authors turn the potentialflow around the surface irregularities in a pressure conduit and semi-infinite platforms intoDirichlet problem.Based on Schwarz formula and by the application of Plemelj's formula,theauthors change the problem into the integration of a Cauchy boundary integral equation in theflow plane through the substitution of variables.Using numerical integration,the authors obtainthe velocity distribution and pressure coefficient along surface irregularities and platforms.Thephysical concept of this method is clear,the convergent speed is rapid and the computative effi-ciency is high.The calculated values agree well with the measured results.It is an effective andsimple method in solving potential flow.     

NUMERICAL SIMULATION OF FLOW THROUGH ORIFICE ENERGY-DISSIPATORS IN XIAOLANGDI FLOOD-DISCHAR-GE TUNNEL

1.　INTRODUCTIONThe Xiaolangdi project_ a key water conservancy project on the Yellow River_ isbeing built just now. According to the design scheme. three orifice energy-dissipators willbe installed in each flood-discharge tunnel. It is for the first time that orifice energy-dissipators are used in a large-scale hydraulic engineering.As a kind of internal energy-dissipator,orifices have the following advantages:energy dissipation region is shortand easyto control,and the flow pattern is …     

NUMERICAL SIMULATION OF TIP-CLEARANCE FLOW IN CASCADE

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｉｐ ｃｌｅａｒａｎｃｅｆｌｏｗｓｏｃｃｕｒｉｎｖａｒｉｏｕｓｅｎｇｉｎｅｅｒ ｉｎｇａｐｐｌｉｃａｔｉｏｎｓｓｕｃｈａｓａｘｉａｌ ｆｌｏｗ ｐｕｍｐｓａｎｄｄｕｃｔ ｅｄｐｒｏｐｅｌｌｅｒｓ .Ｔｈｅｉｎｅｒｔｉａｌｆｏｒｃｅｓａｃｔｉｎｇｕｐｏｎｔｈｅｆｌｕｉｄｉｎｔｈｅｎａｒｒｏｗ ｇａｐｂｅｔｗｅｅｎｂｌａｄｅｔｉｐａｎｄｔｈｅｓｕｒｒｏｕｎｄｉｎｇｗａｌｌａｒｅｓｕｆｆｉｃｉｅｎｔｔｏ ｇｅｎｅｒａｔｅａｔｉｐｌｅａｋａｇｅｖｏｒｔｅｘｏｎｔｈｅｓｕｃｔｉｏｎｓ…     

NUMERICAL SIMULATION OF NONLINEAR WAVE FLOW AROUND COCHLEA CHANNELED STERN SHIPS

A nonlinear method based on Gadd's model [1] [2] is developed to simulate the wave flow around cochlea-channeled stern ships. The subsurface division method is capable of dividing the complicated hull into panels and defining the computer simulated 3-D graphs. Good results are obtained and depicted by computer graphs.     

NUMERICAL SIMULATION OF ATOMIZATION RAINFALL AND THE GENERATED FLOW ON A SLOPE

This article studies the atomization rainfall and the generated flow on a slope by numerical simulations.The atomization rainfall is simulated by a unified model for splash droplets and a suspended mist,and the distribution of the diameter of splash rain drops is analyzed.The slope runoff generated by the atomization rainfall is simulated by a depth-averaged 2-D model,and the localization of the rainfall intensity in space is specially considered.The simulation results show that:(1) the median rain size of the atomization rainfall increases in the longitudinal direction at first,then monotonously decreases,and the maximum value is taken at the longitudinal position not in consistent with the position where the maximum rain intensity is taken.In the lateral direction the median rain size monotonously decreases,(2) since the atomization rainfall is distributed in a strongly localized area,it takes a longer time for its runoff yield to reach a steady state than that in the natural rainfall,the variation ranges of the water depth and the velocity in the longitudinal and lateral directions are larger than those in the natural rainfall.