ON THE MECHANISM OF TURBULENT COHERENT STRUCTURE（II）──A PHYSICAL MODEL OF COHERENT STRUCTURE FOR THE ROUGH BOUNDARY LAYER

（刘宇陆）（蔡树棠）ＯＮＴＨＥＭＥＣＨＡＮＩＳＭＯＦＴＵＲＢＵＬＥＮＴＣＯＨＥＲＥＮＴＳＴＲＵＣＴＵＲＥ（ＩＩ）──ＡＰＨＹＳＩＣＡＬＭＯＤＥＬＯＦＣＯＨＥＲＥＮＴＳＴＲＵＣＴＵＲＥＦＯＲＴＨＥＲＯＵＧＨＢＯＵＮＤＡＲＹＬＡＹＥＲ￥ＬｉｕＹｕｌｕ；Ｃ...     

ON THE MECHANISM OF TURBULENT COHERENT STRUCTURE (I)──THE PYSICAL MODEL OF THE COHERENT STRUCTUREFOR THE SMOOTH BOUNDARY LAYER

In this paper, based on the discussion of properties of the turbulent coherent structure for smooth boundary layer, a physical model has been established. The width of slowly-moving streak line and bursting time of coherent structure expressed by momentum thickness Reynolds number of boundary layer have been obtained, which are in agreement with the experimental data^[3,4,5,7] Project supported by the National Natural Science Foundation of China     

ON THE MECHANISM OF TURBULENT COHERENT STRUCTURE (III)──A STATISTICAL AND DYNAMICALMODEL OF COHERENT STRUCTURE AND ITSHEAT TRANSFER MECHANISM

I.IntroductionItisaveryinlportulltdiscoveryofcoherentstrLICturcinshetlrturbulellt11owsbyexperimentinthelate1950s,whichleadsustoseekthenaturall,ropertiesofturbulcllcefromthenewideaandilladifferentway.ThestudyofthecoherclltstrLlcttlrcisofgreatimportallcetounderstandthegeneration,developmentanddecayof'tLlrbulellce,allditlsoconstructsInorerealisticturbulencemodeltheory.Meanwhile,itwillbeor11elpIYomengineerillgpoint,suchaslllassandheattrallslbr,dl'agI.eductiolland11oisecontrolproblems.Soinlnlel…     

ON THE MECHANISM OF TURBULENT COHERENT STRUCTURE (III)──A STATISTICAL AND DYNAMICAL MODEL OF COHERENT STRUCTURE AND ITS HEAT TRANSFER MECHANISM

Following Tsai & Ma^[1] and Tsai & Liu^[2], a statistical and dynamical near-wall turbulent coherent structural model with separate consideration of two different portions: locally generated and upstream-transported large eddies has been established. With this model, heat transfer in a fully developed open channel in the absence of pressure gradient is numerically simulated. Database of fluctuations of velocity and temperature has also been set. Numerical analysis shows the existence of high-low temperature streak caused by near-wall coherent structure and its swing in the lateral direction. Numerical results are in accordance with the computations and experimental results of other researchers.     

THE METHOD OF TRANSFORMATION OF THE BOUNDARIES FOR STRUCTURE THE ADMISSIBLE DISPLACEMENTS

In this paper the method of transformation of the boundaries for structure theadmissible displacements with various boundary conditions is presented What is called themethod of transformation of the boundaries is that. first we transform the actual systeminto the basic system and additional boundary forces and displacements on the basis of thesuperposition principle, then apply variational principles to the basic system,finally find thepermissible displacement of the actual system by means of the method of transformation ofthe series.In this paper, we also give mixed energy prinapies under Variation of boundaryconditions. The mixed energy principles as the potential and complementary energyprinciples under variation of boundary conditions are all the chief theoretical fundamentalof the method of transformation of the boundaries.Applying the method of transformation of the boundaries. we form the permissibledisplacements of rectangular plates of plane stress and bending problems with various edgeconditio     

REMABKS ON THE STRUCTURE OF EVOLUTION EQUATIONS

ＲＥＭＡＢＫＳＯＮＴＨＥＳＴＲＵＣＴＵＲＥＯＦＥＶＯＬＵＴＩＯＮＥＱＵＡＴＩＯＮＳＪ．Ｂａｄｕｒ；ＳｕｎＢｏｈｕａ（孙博华）（Ｒｕｈｒ－ＵｎｉｒｅｒｓｉｔＢｏｃｈｕｍ，ＬｅｈｒｓｔｕｈｌｆｒＡｌｌｇｅｍｅｉｎｅＭｅｃｈａｎｉｋＤ－４４７８０Ｂｏｃｈｕ...     

TURBULENT COHERENT STRUCTURE AND DYNAMIC SYSTEM

The main difficulties in the study of turbulence via dynamic system lie in how to relatecontinuum systems of infinite dimension with dynamic system in low dimension space andhow to depict its special structure.In this paper,we’ll give a comprehensive review onvarious methods to describe complex systems in low dimension space and new approaches tothe resolution of turbulence problems.     

THE ANALYSES OF THE THREE-DIMENSIONAL STRESS STRUCTURE NEAR THE CRACK TIP OF MODE Ⅰ CT SPECIMENS IN ELASTICPLASTIC STATE(Ⅱ)—THE ANALYSES OF THE STRESS STRUCTURE

Based on[1],the stress structures of the smooth region and shear lip of thespecimens have been investigated in the paper.The characteristics of the stress structure inthe smooth region have been found that the variable z can separated out;the stressesin the midsection can be obtained by the plane strain FEM results or HRR structuremodified by the stress triaxiality.The effects of load level and thickness on the stressstructure can be reflected by the distribution of CTOD along the thickness direction.The obtained expressions of the stresses are very simple and visualized.The analysesof the stress structure in the shear lip show that the stresses can be obtained bydifferent methods of interpolation to a certain precise degree.A new degree parameter of the plane strain state has been put forward andstudied.The parameter can reflect relatively well the variation of the kind andthickness of the specimen as well as the load level.The fracture parameter has alsobeen investigated to be sure that it can be obta     

THE ANALYSES OF THE THREE-DIMENSIONAL STRESS STRUCTURE NEAR THE CRACK TIP OF MODE I CT SPECIMENS IN ELASTICPLASTIC STATE(II)—THE ANALYSES OF THE STRESS STRUCTURE

Based on [1], the stress structures of the smooth region and shear lip of the specimens have been investigated in the paper. The characteristics of the stress structure in the smooth region have been found that the variable z can separated out; the stresses in the midsection can be obtained by the plane strain FEM results or HRR structure modified by the stress triaxiality. The effects of load level and thickness on the stress structure can be reflected by the distribution of CTOD along the thickness direction. The obtained expressions of the stresses are very simple and visualized. The analyses of the stress structure in the shear lip show that the stresses can be obtained by different methods of interpolation to a certain precise degree. A new degree parameter of the plane strain state has been put forward and studied. The parameter can reflect relatively well the variation of the kind and thickness of the specimen as well as the load level. The fracture parameter has also been investigated to be sure that it can be obtained by modified CTOD with the stress triaxiality.     

ON THE DYNAMICAL STRUCTURE OF THE WIND FIELD OF JUPITER''''S GREAT RED SPOT

Based on the geographic approximation the two-dimensional dynamical structure of the wind fields of Jupiterls Great Red Spot and White Oval BC is obtained. The results of calculation are in good agreement with the observations. Thus, an explanation of the observed dispersion of the velocities along the horizontal streamline is given. The major physical mechanism of this dispersion is as follwos: The distance between two adjacent elliptical streamlines varies along the elliptical streamline; leading to the variance of the normal pressure gradient. Thus, the horizontal velocity V_T has to vary correspondingly so that the Coriolis force can approximately balance the normal pressure gradient Another less important factor, i.e., the change of the Coriolis force parameter with the latitude, is also taken into account. The distributions of the vorticities of GRS and White Oval BC are also calculated.     

ON THE STRUCTURE OF CONTINUA AND THE MATHEMATICAL PROPERTIES OF ALGEBRAIC ELASTODYNAMIC OF A TRICLINIC STRUCTURAL SYSTEM

This paper is neither laudatory nor derogatory but it simply contrasts with what mightbe called elastostatic(or static topology),a proposition of the famous six equations.Theextension strains and the shearing strainsfor all i,j,k=1,2,3.which were derived by A.L.Cauchy,are linearly expressed in terms of nine partialderivatives of the displacement function(u_i,u_j,u_k)(?)u(x~i,x~j,x~k)and it is impossiblefor the inverse proposition to sep up a system of the above six equations in expressing thenine components of matrix((?)(u_i,u_j,u_k)/(?)(x~i,x~j,x~k)).This is due to the fact that ourgeometrical representations of deformation at a given point are as yet incomplete .On theother hand,in more geometrical language this theorem is not true to any triangle,exceptorthogonal,for“squared length”in space.The purpose of this paper is to describe some mathematic laws of algebraicelastodynamics and the relationships between the above-mentioned important questions.     

THE DESIGN AND ANALYSIS OF VIBRATION STRUCTURE OF VERTICAL DYNAMIC BALANCING MACHINE

I. INTRODUCTION The shape of some ?ying objects (called workpieces) is similar to that of shafts. These ?ying objectsoften have a large size. Their dispersion e?ect a?ects the ?ying control and the precision in hitting atarget. The dispersion e?ect is the statistical deviation when ?ying objects depart from their preconcerted?ying orbits. As the unevenness of mass distribution is the major cause of the dispersion e?ect, thedouble-plane vertical dynamic balancing technique for ?ying ob…     

A GASEOUS SHOCK WAVE THEORY OF THE GALACTIC SPIRAL STRUCTURE

In this paper, the galactic spiral structure is studied bythe galactic shock wave of interstellar gas with self-gravita-tion. The perturbed gravitation of stars is not a necessarycondition for the existence of such Shock.It is proved firstof all that there exists solution of local Shock wave even ifthe perturbed gravitation is absent.The condition │ω_(no)│>a isrequired for such solution. The spiral structure can onlg beexplained by the shock solution when the difference of densitybetween the regions of arm and interarm is larger. The granddesign of shock wave with self-gravitation is obtained by theiterative method.The features of shock wave can be analyzedqualitatively in the velocity plane for a special perturbedgravitation Which is used to simulate the self-gravitation.ofinterstellar gas.As the mass distribution in proto-galacticdisk is irregular initially.the grand design of the galacticShock wave was developed by the processes of Winding,growth ofinstability and overlapping of waves.Hence.it giv     

STRUCTURE OF THE ATTRACTING SET OF A PIECEWISE LINEAR HNON MAPPING

Detailed structure of the attracting set of the piecewise linear Hnon mapping (x,y)→(1-a|x|+by,x) with a=8/5 and b=9/25 is described in this paper using the method of dual line mapping. Let A and B denote the fixed saddles in the first quadr ant, and in the third quadrant, respectively. It is claimed that (1) the attracting set is the closure of the unstable manifold of saddle B, which includes the unstable manifold of A as its subset, and (2) the basin of attraction is the closure of the stable manifold of A, bounded by the stable manifold of B, which is in the limiting set of the stable manifold of A. Relations of the manifolds of the periodic saddles with the manifolds of the fixed point are given. Symbolic dynamics notations are adopted which renders possible the study of the dynamical behavior of every piece of the manifolds and of every homoclinic or heteroclinic point.     

THE METHOD OF MIXED BOUNDARY CONDITION FOR A KION OF LINEAR AND NONLINEAR COMPOSITE STRUCTURE

This paper deals with the axisymmetrical deformation of shallow shells in largedeflection,which are in conjunction with linear elastic structures at the boundary.A methodof mixed boundary condition for this problem is introduced.then the problem of a compositestructure is transformed into a problem of a single structure and the integral equations aregiven.The perturbation method is used to obtain the solutions and an example of compositestructure consisting of a shallow spherical and a cylindrical shell is presented.     

THE ANALYSES OF THE THREE-DIMENSIONAL STRESS STRUCTURE NEAR THE CRACK TIP OF MODE I CT SPECIMENS IN ELASTICPLASTIC STATE(Ⅰ)—THE ANALYSES OF CONSTRAINT PARAMETERS AND FRACTURE PARAMETERS

In the present paper, three dimensional analyses of some general constraint parameters and fracture parameters near the crack tip. of Mode I CT specimens in two different thicknesses are carried out by employing ADINA program. The results reveal that the constraints along the thickness direction are obviously separated into two parts: the keeping similar high constraint field (Z₁) and rapid reducing constraints one (Z₂). The two fields are experimentally confiremed to correspond to the smooth region and the shear lip on the fracture face respectively. So the three dimensional stress structure of Mode I specimens can be derived through discussing the two fields respectively. The distribution of the Crack Tip Opening Displacement (CTOD) along the thickness direction and the three dimensional distribution of the void growth ratio (V_g) near the crack tip are also obtained. The two fracture parameters are in similar trends along the thickness direction, and both of them can reflect the effect of thickness and that of the loading level to a certain degree.     

THE ANALYSES OF THE THREE-DIMENSIONAL STRESS STRUCTURE NEAR THE CRACK TIP OF MODE I CT SPECIMENS IN ELASTICPLASTIC STATE(Ⅰ)—THE ANALYSES OF CONSTRAINT PARAMETERS AND FRACTURE PARAMETERS

In the present paper,three dimensional analyses of some general constraintparameters and fracture parameters near the crack tip of Mode I CT specimens in twodifferent thicknesses are carried out by employing ADINA program.The results revealthat the constraints along the thickness direction are obviously separated into twoparts:the keeping similar high constraint field(Z_1)and rapid reducing constraintsone(Z_2).The two fields are experimentally confiremed to correspond to the smoothregion and the shear lip on the fracture face respectively.So the three dimensionalstress structure of Mode I specimens can be derived through discussing the two fieldsrespectively.The distribution of the Crack Tip Opening Displacement(CTOD)alongthe thickness direction and the three dimensional distribution of the void growth ratio(V_9 )near the crack tip are also obtained.The two fracture parameters are in similartrends along the thickness direction,and both of them can reflect the effect ofthickness and that of the loading l     

STUDY FOR THE BIFURCATION TOPOLOGICAL STRUCTURE AND THE GLOBAL COMPLICATED CHARACTER OF A KIND OF NONLINEAR FINANCE SYSTEM(Ⅰ)

ＩｎｔｒｏｄｕｃｔｉｏｎＣｈａｏｔｉｃｉｓｔｈｅｉｎｈｅｒｅｎｔｒａｎｄｏｍｎｅｓｓｉｎｔｈｅｄｅｆｉｎｉｔｅｓｙｓｔｅｍ .Ｔｈｅｄｅｆｉｎｉｔｅｎｅｓｓｉｓｃａｕｓｅｄｂｙｔｈｅｓｙｓｔｅｍｉｎｔｅｒｎａｌｓｂｕｔｎｏｔｂｙｔｈｅｅｘｔｅｒｎａｌｄｉｓｔｕｒｂａｎｃｅ[1- 4],ｗｈｉｌｅｔｈｅｉｎｈｅｒｅｎｔｒａｎｄｏｍｎｅｓｓｉｓｔｈｅｉｒｒｅｇｕｌａｒａｎｄｄｉｆｆｉｃｕｌｔ＿ｔｏ＿ｂｅ＿ｐｒｅｄｉｃｔｅｄｂｅｈａｖｉｏｒｏｆｔｈｅｓｙｓｔｅｍ[5 ,6 ].Ｗｈａｔｉｓｍｏｓｔａｔｔｒａｃｔｉｖｅ…     

SYMPLECTIC STRUCTURE OF POISSON SYSTEM

When the Poisson matrix of Poisson system is non-constant, classical symplectic methods, such as symplectic Runge-Kutta method, generating function method, cannot preserve the Poisson structure. The non-constant Poisson structure was transformed into the symplectic structure by the nonlinear transform.Arbitrary order symplectic method was applied to the transformed Poisson system. The Euler equation of the free rigid body problem was transformed into the symplectic structure and computed by the midpoint scheme. Numerical results show the effectiveness of the nonlinear transform.     

STUDY FOR THE BIFURCATION TOPOLOGICAL STRUCTURE AND THE GLOBAL COMPLICATED CHARACTER OF A KIND OF NONLINEAR FINANCE SYSTEM(Ⅱ)

ＩｎｔｒｏｄｕｃｔｉｏｎＣｈａｏｔｉｃｉｓｔｈｅｉｎｈｅｒｅｎｔｒａｎｄｏｍｎｅｓｓｉｎｔｈｅｄｅｆｉｎｉｔｅｓｙｓｔｅｍ .Ｔｈｅｄｅｆｉｎｉｔｅｎｅｓｓｉｓｃａｕｓｅｄｂｙｔｈｅｓｙｓｔｅｍｉｎｔｅｒｎａｌｓｂｕｔｎｏｔｂｙｔｈｅｅｘｔｅｒｎａｌｄｉｓｔｕｒｂａｎｃｅ,ｗｈｉｌｅｔｈｅｉｎｈｅｒｅｎｔｒａｎｄｏｍｎｅｓｓｉｓｔｈｅｉｒｒｅｇｕｌａｒａｎｄｄｉｆｆｉｃｕｌｔ＿ｔｏ＿ｂｅ＿ｐｒｅｄｉｃｔｅｄｂｅｈａｖｉｏｒｏｆｔｈｅｓｙｓｔｅｍ .Ｗｈａｔｉｓｍｏｓｔａｔｔｒａｃｔｉｖｅｏｆｔｈｅｃ…