力学学报

In this paper, the first approximation solutions of the incompressible plane turbulent mixing layer using the theories of Chou Peiyuanhave been given. We consi-der the continuity equation, the mean motion equations and the equations of the double velocity correlations, and ignore the triple velocity correlations of the double velocity correlation equations. We introduce the hypothesis of the self-preservation, and have gotten the theoretical results of the mean velocities, the double velocity correlations a...

1990, 22(1): 1-8. doi: 10.6052/0459-1879-1990-1-1995-904

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VISCOUSrINVISCID INTERACTION FLOW THEORY

A theory of viscous-inviscid interaction flow for incompressible, laminar, two-dimensional case is presented in this paper. Main points of this theory are as follows. 1) the interaction flow can be divided into three layers, in the normal direction perpendicular to the main streamwise direction. The three layers are viscous layer, interaction layer and inviscid layer, respectively. A concept of interaction layer where the momentum transferring in the normal direction plays a leading role is introduced. 2) W...

1990, 22(1): 9-19. doi: 10.6052/0459-1879-1990-1-1995-905

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THE DIFFRACTION OF SOLITARY WATER WAVE ON THREE-DIMENSIONAL FLOATING BO DIES

Depth averaged Boussinesj equations are usually used as governning equations for the nonlinear water wave motions in shallow water. These equations, however, are not applied in the vicinity of floating bodies or underwater" obstacles, in which the variation of the fluid flow in depth cannot be ignored.By using the method of matched asymptotic expansions and the idea of edge layer, a mathematical model for describing the interaction between weakly nonlinear shallow water waves and three-dimensional floating ...

1990, 22(1): 20-27. doi: 10.6052/0459-1879-1990-1-1995-906

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NUMERICAL MODELING OF THREE-DIMENSIONAL TURBULENT RECIRCULATING GAS-PARTICLE FLOWS IN A COMBUSTOR OF CO-FLOW JETS WITH LARGE VELOCITY DIFFERENCE

The three-dimensional turbulent recirculating gas-particle flows in a combus-tor of co-flow jets with large velocity difference are simulated by the multi-fluid model and k-8 turbulence model. Predicted results of gas velocity, particle velocity and particle mass flux distributions are in qualitative agreement with experiments, and reveal the machanism of flame stabilization and combustion intensification in such combustors. The discrepancy between pre--dictions and experiments, especially ,in turbulence in...

1990, 22(1): 28-34. doi: 10.6052/0459-1879-1990-1-1995-907

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ASYMPTOTIC SOLUTION FOR BUCKLING OF TOROIDAL SHELLS

Stability equations for toroidal shells under hydrostatic pressure are derived from Sanders' nonlinear equations of equilibrium and the equation of compatibility. They are solved by the use of asymptotic method. Theoretically predicted buckling pressures are in good agreement with experimental results obtained by Fishlowitz. The effect of prebuckling deflection on critical loads is investigated.

1990, 22(1): 35-44. doi: 10.6052/0459-1879-1990-1-1995-908

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RESISTIVE TEARING MODE IN MOVING PLASMA

The resistive tearing mode in a nonuniformly flowing plasma is discussed in the present paper. It is shown that the effect of velocity magnitude and distribution nonuni-formityy on resistive tearing mode is destabilizing. In addition, the shapes of magnetic islands are also given.

1990, 22(1): 45-52. doi: 10.6052/0459-1879-1990-1-1995-909

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THE NONLINEAR RESPONSES OF A FORCED TWO-DEGREE-OF-FREEDOM STRUCTURE

In this paper the nonlinear responses of a forced TDOF structure are investigated. There are some highly nonlinear and coupling terms in the motion equation of the system. Firstly, the responses of the system to deterministic excitation are calculated by the Re-cursive-digital-Filtering-Technich (RDFT). Then the responses of the system to random excitation are calculated by the Simulation Method based on RDFT and the Ito's Calculus-cum-Si-mulation-Method (ICSM).The results show that the ICSM is more efficie...

1990, 22(1): 53-59. doi: 10.6052/0459-1879-1990-1-1995-910

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ON THE EQUIVALENT OF THE WILSON ELEMENT WITH THE GENERALIZED HYBRID ELEMENT

In this paper eqivalent of the generalized hybrid element with the modified Wilson element, which is derived by the generalized hybrid method, is proved. The Wilson element in case of rectangular and the modified Wilson element Qmm5 can be regarded as a special generalized hybrid element.

1990, 22(1): 60-64. doi: 10.6052/0459-1879-1990-1-1995-911

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NONLINEAR STABILITY AND BIFURCATIONS OF AXISYMMETRIC HEAVY (GYROSCOPE

In this paper, the nonlinear stability criteria in the sense of Movchan for the permanent rotations of axisymmetric heavy gyroscopes in the presence of perfect dissipa-tive force are given. The main subdomains of the regions of asympototic stability are given and the bifurcation phenomena are discussed in detail.

1990, 22(1): 65-73. doi: 10.6052/0459-1879-1990-1-1995-912

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INFLUENCE OF EXTERNAL MAGNETIC FIELD ON THE FLOWFIELD OF MOLTEN SEMICONDUCTORS DURING CZO-CHRALSKI CRYSTAL GROWTH PROCESS -ANUMERICAL SIMULATION

. Numerical results show that the external magnetic field influences significantly the flow field of molten semiconductors during Czochralski crystal growth process. The melt flow could be heavily damped by a magnetic field with intensity of several thousand gauss, while the temperature field is nearly unaffected because of very low Prandtl number.

1990, 22(1): 74-78. doi: 10.6052/0459-1879-1990-1-1995-913

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ENTRANCE CONVERGING FLOW ANALYSIS FOR NON-NEWTONIAN FLUIDS

In this paper, a converging flow of Non-newtonian fluids in an entrance has been discussed. Considering the stick-slip behavior of viscoelastic liquids in this ;,flow, an extended equation in converging flovy boundary streamline and an extended equation of natural converging conical angle in entry flow are derived, using a theory of minimal energy. And then, the results are compared with those given in literature.

1990, 22(1): 79-85. doi: 10.6052/0459-1879-1990-1-1995-914

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PROBLEM OF ACCELERATING PLATE IN WATER CHANNEL

In this paper, we analyze by Lagrangian method the problem of a plate moving horizontally with an acceleration towards a fluid which is initially at rest. The nonlinear free surface boundary conditions are satisfied exactly. The results obtained roughly agree with [2] .

1990, 22(1): 86-90. doi: 10.6052/0459-1879-1990-1-1995-915

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ELASTO-PLASTIC ANALYSIS OF CYLINDRICAL SHALLOW SHELLS

This paper suggests the use of discrete least square method, one of the methods of weighted residuals, to analyse the elasto-plastic solution of a cylindrical shallow shell. The method presented in this paper may be uso-plastic solution of a cylindrical shallpw .shell, shallow shells with more complex loadings and boundary conditions.The use of the weighted residual method has specific advantages: simplicity; accuracy, quickness, less work and cost, very suitable to be used in micro computers in practice.

1990, 22(1): 91-94. doi: 10.6052/0459-1879-1990-1-1995-916

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THE ESTABLISHMENT OF THE GENERAL DYNAMIC EQUATIONS OF TREE-STRUCTURE RIGID BODIES SYSTEM WITH BALL JOINTS

A new method of establishing the dynamic equations of the multi-rigid-body system with tree-structure and the ball-joints is proposed. With the help of the dynamics of constrained system and the differential geometry, the concept of "generalized body" is put forward to replace the sub-system of the multi-rigid body system. By the extension of the generalized body, the recursive algorithm of the establishment of the dynamic equations of the constrained system is derived

1990, 22(1): 95-98. doi: 10.6052/0459-1879-1990-1-1995-917

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AN EXTENSION OF NEW FORM CANONICAL EQUATIONS TO GENERALIZED CLASSICAL MACHANICS

In this paper, the new form canonical equations are extended to the generalized classical mechanics and the generalized canonical equations are obtained. Then the generalized Poisson and Lagrange brackets and their characteristics are defined. The generalized canonical equations are expressed by Poisson bracket notation. In addition, the generalized Hamilton Variational principle and Hamilton-Jacobi's equations are established.

1990, 22(1): 99-105. doi: 10.6052/0459-1879-1990-1-1995-918

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MOLECULAR DYNAMICS SIMULATIONS OF GRAIN BOUNDARY STRUCTURES AT 0°K IN COPPER WITH SUBSTITUTIONAL IMPURITIES

The 0°K relaxed structures of grain boundaries in Cu and its alloys (Cu-Ag, Cu-Bi) were simulated with molecular dynamics method by using a five-parameter potential and constant volume assumption.In these cases, the results showed that the atomic distribution was periodic in the two directions paralled to the grain boundary and it was mirror-symmetric in the direction perpendicular to the boundary. The difference between relaxed structures of Cu and its alloys was small, nevertheless, the host atoms were cl...

1990, 22(1): 106-109. doi: 10.6052/0459-1879-1990-1-1995-919

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NUMERICAL ANALYSIS OF STABILITY FOR REVOLUTIONARY THIN SHELL

An analysis by the finite element method is presented for solving linear buckling probems of revolutionary thin shell. A general nonlinear strain-displacement relationship is used in the stability formulation which is based on the energy criterion. Under certain assumptions, the problem is reduced to a generalized eigenvalue problem. In the F. E, M, calculation, the coupling between harmonics is taken into consideration. The method is applied to several examples and the results are compared with the theoret...

1990, 22(1): 110-114. doi: 10.6052/0459-1879-1990-1-1995-920

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MOIRE INTERFEROMETRY OF STICKING FILM

In order to obtain a 1-D or 2-D moire pattern, a holographic film is adhered to the surface of the specimen and a densely covered grating is prepared in the film by holographic interference directly. A warping wavefront generated by a load is recorded, then the film is removed from the specimen for treatment; This method has many advantages and has broad prospects of applications, because it combines and simplifies the preparation of grating and measuring process.This paper expounds principles of the prepar...

1990, 22(1): 115-123. doi: 10.6052/0459-1879-1990-1-1995-921

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ANTIPLANE LINE FORCE IN NONLOCAL ELASTICITY

The classical line force problem is generalized to the case of nonlocal elasticity. The analytical expressions of both the antiplane line fprce and its stress field, have been obtained. None of the classical singularities exist in the stresses. Because of the nonlocal effect, the antiplane nonlocal line force has a Gaussian distribution quile different from the distribution of the classical line force and it satisfies the generalized line force definition.

1990, 22(1): 124-126. doi: 10.6052/0459-1879-1990-1-1995-922

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1990 Vol. 22, No. 1

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