PIV TECHNIQUE AND ITS APPLICATION IN SHIP HYDRODYNAMICS

1.　ＩＮＴＲＯＤＵＣＴＩＯＮＢｙｃｏｍｂｉｎｉｎｇｔｈｅｆｌｏｗｖｉｓｕａｌｉｚａｔｉｏｎ,ｌａｓｅｒｔｅｃｈｎｉｑｕｅａｎｄｉｍａｇｅｐｒｏｃｅｓｓｉｎｇｔｅｃｈｎｉｑｕｅｓ,ｔｈｒｏｕｇｈａｂｏｕｔ20ｙｅａｒｓｄｅｖｅｌｏｐｍｅｎｔ),ＰＩＶ(Ｐａｒ?..     

ON NONLINEAR STABILITY IN NONPARALLEL BOUNDARY LAYER FLOW

The nonlinear stability problem in nonparallel boundary layer flow for two-dimensional disturbances was studied by using a newly presented method called Parabolic Stability Equations (PSE). A series of new modes generated by the nonlinear interaction of disturbance waves were tabulately analyzed, and the Mean Flow Distortion (MFD) was numerically given. The computational techniques developed,including the higher-order spectral method and the more effective algebraic mapping, increased greatly the numerical accuracy and the rate of convergence. With the predictor-corrector approach in the marching procedure, the normalization condition was satisfied, and the stability of numerical calculation could be ensured. With different initial amplitudes, the non linear stability of disturbance wave was studied. The results of examples show good agreement with the data given by the DNS using the full Navier-Stokes equations.     

BOUNDARY LAYER EFFECTS ON SOLID PARTICLE MOTION AND EROSIVE WEAR

ＢＯＵＮＤＡＲＹＬＡＹＥＲＥＦＦＥＣＴＳＯＮＳＯＬＩＤＰＡＲＴＩＣＬＥＭＯＴＩＯＮＡＮＤＥＲＯＳＩＶＥＷＥＡＲＬｉｕＸｉａｏ－ｂｉｎｇ（ＳｉｃｈｕａｎＩｎｓｔｉｔｕｔｅｏｆＴｅｃｈｎｏｌｏｇｙ，Ｃｈｅｎｇｄｕ６１１７４４，Ｐ．Ｒ．Ｃｈｉｎａ）Ｃｈｅｎ...     

EFFECTS OF SURFACE CURVATURES ON HYDRAULIC CHARACTERISTICS AND TURBULENT BOUNDARY LAYER

Some hydraulic measurements have been made in buckets of model overflowdams.The effects of surface curvatures of buckets on velocity,pressure and turbulent boundarylayer have been systematically investigated.The results have shown that the effects of surfacecurvatures on velocity distributions are unproportional and the centrifugal pressure coefficientdefined in the report possesses a transitional quality.A definition of turbulent boundary layerthickness of bucket is suggested and the development of turbulent boundary layer is indicated ex-perimentally.It is found the maximum value of relative boundary layer thickness appears about0.25 of relative arc length.     

THEORY AND CONSERVATION THEOREM OF VORTICITY FLUX IN TRANSPORT

According to the theory of the transport and vorticity dynamics,the paper establishes the theory of vorticityflux and the conservation theorem between the vorticity flux and vortex strength in a plane flow.The theory ofvorticity flux is a basic one in research on turbulence.     

TURBULENT BOUNDARY LAYER DEVELOPMENT IN THE ENTRANCE REGION OF A SMOOTH ROUND PIPE

The study of the turbulent boundary layer along a smooth round pipe is of greatsignificance both in practice and in theory.In this paper,the formulae for calculating the tur-bulent boundary layer thickness are obtained by solving the momentum integral equation of theboundary layer in which the assumptions of the logarithmic law and exponential law of velocitydistribution are adopted.The methods for calculating the mean flow velocity in the developingregion of turbulent boundary layer in a round pipe are proposed.The relation between the expo-nent n and the factor μ·δ/ν is studied and a formula for calculating the exponent n is obtained.     

THREE－DIMENSIONAL MODELLING OF HYDRODYNAMICS AND WATER QUALITY IN COASTAL WATERS

ＴＨＲＥＥ－ＤＩＭＥＮＳＩＯＮＡＬＭＯＤＥＬＬＩＮＧＯＦＨＹＤＲＯＤＹＮＡＭＩＣＳＡＮＤＷＡＴＥＲＱＵＡＬＩＴＹＩＮＣＯＡＳＴＡＬＷＡＴＥＲＳ￥ＳｈｅｎＹｏｎｇ－ｍｉｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＣｉｖｉｌＥｎｇｉｎｅｅｒｉｎｇ，ＤａｌｉａｎＵｎｉｖ...     

DISCUSSION ON RELATION BETWEEN BOUNDARY LAYER AND WALL EROSION CAUSED BY STRIKING OF PARTICLES

The kinetic characteristics of particles moving through laminar or turbulent boundary layer are computed anddifferent erosive situations caused by striking of particles are compared. The function of anti-erosion sinews addedon the blades is analysed. The energy detrition in the two-phase turbulent flow is discussed. The content is helpfulto the design of anti-erosion fans.     

NUMERICAL STUDY FOR EVOLUTION OF COHERENT VORTEX IN UNIDIRECTIONAL OSCILLATORY BOUNDARY LAYER OVER SAND RIPPLES

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＳｈｅａｒｆｌｏｗｓｐａｓｔｗａｖｙ ｌｉｋｅｂｏｕｎｄａｒｉｅｓｈａｖｅａｔ ｔｒａｃｔｅｄｃｏｎｓｉｄｅｒａｂｌｅａｔｔｅｎｔｉｏｎｉｎｒｅｃｅｎｔｙｅａｒｓｂｅ ｃａｕｓｅｏｆｔｈｅｃｅｎｔｒａｌｒｏｌｅｔｈｅｙ ｐｌａｙｉｎｓｅｖｅｒａｌｉｎ ｔｒｉｇｕｉｎｇ ｐｈｅｎｏｍｅｎａ ,ｓｕｃｈａｓｔｈｅ ｇｅｎｅｒａｔｉｏｎｏｆｗｉｎｄｗａｖｅｓｏｎｗａｔｅｒ ,ｔｈｅｆｏｒｍａｔｉｏｎｏｆｓｅｄｉｍｅｎｔａ ｒｙｒｉｐｐｌｅｓａｎｄｄｕｎｅｓｉｎｄｅｓｅｒｔｓａｎｄｒｉ…     

EFFECT OF SOLID PARTICLES ON STABILITY FLOW IN THE BOUNDARY LAYER ON A FLAT PLATE

ＥＦＦＥＣＴＯＦＳＯＬＩＤＰＡＲＴＩＣＬＥＳＯＮＳＴＡＢＩＬＩＴＹＦＬＯＷＩＮＴＨＥＢＯＵＮＤＡＲＹＬＡＹＥＲＯＮＡＦＬＡＴＰＬＡＴＥ￥ＬｉｎＪｉａｎ－ｚｈｏｎｇ；ＺｈｏｕＺｅ－ｘｕａｎＤｅｐａｒｔｍｅｎｔｏｆＭｅｃｈａｎｉｃｓ，ＳｔａｔｅＫｅｙＬａ...     

A COMPUTATIONAL STUDY ON BACKWARD SWIMMING HYDRODYNAMICS IN THE EEL ANGUILLA ANGUILLA

1. INTRODUCTION It is well known that most aquatic vertebrates swi mby a traveling wave propagating fromheadto tail . However ,a few fish species can swi m back- ward by reversing the direction of the traveling wave along the body . Backward swi mming is used for escape from predators and for maneuvering in complex environments[1 ,2]. All these species such as eels , moray eels and congers[3]have elongated and flexible bodies and swi m forward and back- wardinthe anguilliform mode with mo…     

EXPERIMENTAL STUDIES AND NUMERICAL CALCULATION ON TURBULENT BOUNDARY LAYER OF WATER FLOW ALONG CURVED SURFACE

This paper will introduce experimental studies and numerical calculation onturbulent boundary layer of water flow along curved surface in our country in recent years.Onthe basis of the experimental studies,the effects of curvature and roughness on velocitydistribution and pressure distribution and the change of turbulent flow boundary layer onoverflow bucket concave surface is discussed.We proposed the empirical formula of velocity,pressure and the change of turbulent flow boundary layer on outlet bucket concave.According tothe momentum principle,we have deduced the momentum integral equation full water depthboundary layer and using the element as control unit inside the boundary layer on concavesurface of bucket.Combining with continuity equation,we have computed the boundary layerdevelopment on the bucket of a spillway.Compared with the field experimental data,thecalculation results are available.Under polar coordinates,a mathematical model for simulatingtime-averaged flow characteristics in concave surface of bucket is established.The turbulent flowfield on concave surface of bucket is calculated by SIMPLE method and this mathematicalmodel.The flow velocity field,pressure field,distribution of turbulent kinetic energy,distribution of turbulent energy dissipating rate and distribution of shear stress are available.Thecalculation value is consistent with measured test data.     

SECONDARY INSTABILITY WITH RESPECT TO SPATIAL GROWING THREE－DIMENSIONAL SUBHARMONIC DISTURBANCES IN BOUNDARY LAYER FLOW WITH SUCTION

ＳＥＣＯＮＤＡＲＹＩＮＳＴＡＢＩＬＩＴＹＷＩＴＨＲＥＳＰＥＣＴＴＯＳＰＡＴＩＡＬＧＲＯＷＩＮＧＴＨＲＥＥ－ＤＩＭＥＮＳＩＯＮＡＬＳＵＢＨＡＲＭＯＮＩＣＤＩＳＴＵＲＢＡＮＣＥＳＩＮＢＯＵＮＤＡＲＹＬＡＹＥＲＦＬＯＷＷＩＴＨＳＵＣＴＩＯＮ￥ＺｈａｏＧｅｎ...     

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.     

QUADRANT ANALYSIS OF BUBBLE INDUCED VELOCITY FLUCTUATIONS IN A TRANSITIONAL BOUNDARY LAYER

Our previous study showed that the frictional drag decreases with increasing void fraction at Re > 1300, while it increases at Re < 1000. Decomposition of the Reynolds shear stress also implied that bubbles induce isotropy of turbulence. In order to confirm our previous analysis and to further investigate flow fields in the vicinity of bubbles, we analyze velocity fluctuations on the quadrant space in the streamwise and transverse directions ( u′ – v′ plane). Here, we focus on two specific Reynolds numbers ...