力学学报

IMPLICIT FINITE VOLUME METHOD FOR THREE-DIMENSIONALNAVIER-STOKES COMPUTATION

In this study, a new fully-implicit finite-volume numerical algorithm is developed tosolve the time-dependent Navier-Stokes equations using NND finite difference scheme. Both inviscid and viscous fluxes across cell boundaries are treated implicitly. The present work emphasizesthe finite-volume approximation of the integral form of the conservation laws. The integral approach enhances both stability and accuracy of the algorithm. Nonequilibrium reacting hypersonicionizing air viscous flows over the reentry v...

1998, 30(6): 641-647. doi: 10.6052/0459-1879-1998-6-1995-172

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GALERKIN SOLUTIONS OF LAMINAR FLOW IN HELICAL ELLIPTICAL PIPES

Helloal pipes are used extensively in industrial applications and the secondary flow affects the various aspects of the fluid in them considerably. For this reason, many efforts have been made in this field and mostly focused on planar curved pipe flows. Furthermore, since the circular cross-section is a special elliptical cross-section, the researches of the flow in elliptical pipes must have more profound significant.In terms of tensor analysis technique, the Navier-Stokes equations in a curvilinear coord...

1998, 30(6): 648-655. doi: 10.6052/0459-1879-1998-6-1995-173

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AN EXPERIMENTAL STUDY ON SOME FEATURES OF TURBULENT FRONTS IN STRATIFIED FLUID

Some features on the turbulent fronts were studied experimentally. The turbulence was produced by towing a grid with vertical square bars through a tank filled with linear stratified fluid. The shapes and behaviors of front motions were observed and recorded by shadowgraph and photograph. The data and paxameters of fronts were collected and computed by using an im age-digitized-microcomputer processing system from the traces of fronts.The variation of front pattern with time was examined. The front rapid co...

1998, 30(6): 656-661. doi: 10.6052/0459-1879-1998-6-1995-174

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NUMERICAL INVESTIGATION OF PRESSURE FLUCTUATIONS WITHIN CRACK LAYERS OF LOWER SURFACES OF SLABS

Fluctuating pressure and its propagation within cracks under bed slabs in a plungepool downstream of a high dam are two main factors which cause destruction and scour of bed slabs in a plunge pool. The impingement by a free jet on the slabs in a plunge pool downstream of a large dam creates intense pressure flutuations within the cracks under slabs and causes the bed slabs to be unstable.The instantaneous differences of pressure on the upper and the lower surfaces of bed slabs can generate transient uplift ...

1998, 30(6): 662-671. doi: 10.6052/0459-1879-1998-6-1995-175

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NON-PROMGATING SOLITON AND SURMCE TENSION

The contradictory between experiments and theory about the effect of the surface tension on the non-propagating soliton was discussed in this article. Since the lateral wave length was short, the effect of the surface tension on the non-propagating soliton was discussed by Miles and Zhou. They modified the relation between the frequency and the wave length by the surface tension, and brought it into higher order. According to the theoritical analysis, Zhou divided the kh-σ plane into three regions (Fig.1), ...

1998, 30(6): 672-675. doi: 10.6052/0459-1879-1998-6-1995-176

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A CHAOTIC ATTRACTOR IN THE NORMAL FORM NETWORK

Biological experiments of mammalian brain have shown that real neural systems exhibit a range of phenomena such as oscillations, phase-locking and even chaos. The chaotic behaviors simulate the information processing mechanisms of the real neural systems at a higher level. In this paper the bifurcation and chaos of the high order correlation networks will be studied.In some previous discussions about the high order correlation neural networks, we learned that the high order correlation networks expected to ...

1998, 30(6): 676-681. doi: 10.6052/0459-1879-1998-6-1995-177

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EXPERIMENTS AND THEORETIC ANALYSIS FOR THE FRACTURE OF BRITTLE MATERIALSUNDER BIAXIAL STRESS

The fracture behavior of brittle materials under biaxial plane stress, especially theinfluence of the stress parallel to the crack plane on critical fracture parameters, was investigated by means of thermomechanical method. Biaxial and uniaxial tension tests were performed with thin glass and zirconia disk specimens. The aims of this study is to clarify the fracture dependenceof brittle material in plane stress state and their difference between biaxial and uniaxial tension,baized on experimental and analyt...

1998, 30(6): 682-689. doi: 10.6052/0459-1879-1998-6-1995-178

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CHAOTIC AND HYPERCHAOTIC BEHAVIORS OF VISCOELASTIC RECTANGULAR PLATES UNDER TRANSVERSE PERIODIC LOAD

On the basis of the hypotheses of the Karman theory for elastic thin plates and the Boltzmann laws for linear isotropic viscoelastic materials, the constitutive equations for viscoelasticthin plates airs derived by using the "structure function" introduced in this paper. The initialboundary value problem of nonlinear dynamical analysis for viscoelastic thin plates is formulatedby using the procedure that is similar to the process deriving the Karman theory for elastic thinplates. If Poisson ration v of a ma...

1998, 30(6): 690-699. doi: 10.6052/0459-1879-1998-6-1995-179

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CONTACT PROBLEM IN BUCKLING ANAlYSIS OF DELAMINATED LAMINATES

, Zhenhan Yao

In this paper, the buckling analysis of laminates with an embedded delaminationhas been conducted by employing the finite element method based on the Mindlin plate theory.To avoid the overlap between two delaminated layers in the buckling mode, an effective solutionmethod has been put forward to deal with the contact problem in the buckling analysis. In thismethod, an iterative updating process incorporating the first-order sensitivity gnalysis and thequadratic programming technique has been proposed to com...

1998, 30(6): 700-710. doi: 10.6052/0459-1879-1998-6-1995-180

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PARAMETERS FOR FINITE ROTATIONAL TENSOR AND ITS APPLICATION IN MULTIBODY SYSTEMS

Large deformation of components in multibody systems is usually caused by relativelylarge rotation between the particles in the component. Finite rotational tensors are used to describelarge rotation. To model the motion of the component with finite element methods, the finiterotational tensor must be approximated by nodal paxameters and shape functions. What kind ofparameters are used to represent finite rotational tensor is a fundamental aspect in formalism ofmultibody systems. Euler parameters are most c...

1998, 30(6): 711-718. doi: 10.6052/0459-1879-1998-6-1995-181

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A DYNAMIC CONTROL MODEL OF PIEZOELECTRIC CANTILEVERED BEAM-PLATE BASED ON WAVELET THEORY

Based on the scaling function transform of the Daubechies wavelet theory, an oneto-one explicit relation betWeen electric signals measured in piezoelectric sensors and denectionof the plates is established in this paper, which overcomes the deficiency of conventional methodof modal analysis which sometimes leads to failure of measuring deformation of the plate whenthe inverse matrix in the method does not exist. After that, a dynamic control model for thepiezoelectric plates with feedback of negative deflec...

1998, 30(6): 719-727. doi: 10.6052/0459-1879-1998-6-1995-182

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TIME DOMAIN BEM FOR WAVE PROPAGATION PROBLEMS IN ANISOTROPIC MEDIA AND ITS EXPERIMENTAL VERIFICATIONS

Attributed primarily to the reduction of dimensionality of problems, high accuracyof results and automatic consideration of the radiation conditions at infinity, Boundary ElementMethod (BEM)has become increasingly popular for the solution of linear elastodynamic problems.Time domain Boundary Element Method for wave propagation problems in anisotropic media iseffectively applicable in the research fields of earthquake engineering, rock dynamics and compositedynamics. Due to the complexity of time domain fund...

1998, 30(6): 728-736. doi: 10.6052/0459-1879-1998-6-1995-183

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TURBULENT BOUNDARY LAER STUDY OF FLOW BEHINDSMALL OBSTACLES PLACED ON THE WALL

The solid wall turbulent shear flow behind two-dimensional small obstacles placed onthe plane is numerically simulated using RNG K-ε model and standard K-ε model. The model ofsmall obstacles used in this study have nine types, such as plate, square and cylinder et al. A finitevolume method with the collocated variable arrangement employing orthogonal grids was used tosolve the equation system. The pressure and mean velocity, turbulent energy, dissipation rate ofturbulent energy are coupled by SIMPLE algori...

1998, 30(6): 737-742. doi: 10.6052/0459-1879-1998-6-1995-184

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INTERACTIONS OF THE RIGID-RODLIKE POLYMER AND THE COHERENT STRUCTURES IN A MIXING LAYER

The spectral method, ie. Galerkin method and the pseudo-spectral method wereused to solve the diffusion equation of the distribution function in configurational space for amultibead-rod model and N-S equation respectively. The properties of the coherent structure ina plane mixing layer with rigid-rodlike polymer additives and the most probable orientations ofthe multibead rods were obtained simultaneously. The results indicate that adding polymer tothe Newtonian fluid will make flows have stronger vorticity...

1998, 30(6): 743-747. doi: 10.6052/0459-1879-1998-6-1995-185

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THE EQUIVALENT ROBUST POLE ASSIGNMENT IN VIBRATION CONTROL DESIGN

In this paper, we consider the vibration controllable system where A ∈ R2n×2n,B ∈ R2n×m and X ∈ R2n×1, U ∈ Rm×1,, are the state and input of the above system. If we usestate feedback, that is, if we set U = FX, in which F ∈E Rp×2n, then we haveX = (A + BF)XFrom the control theory we know that if the system is controllable, then for any given numbersλ1，λ2，……λ2n. there exists a matrix F, such that matrix (A + BF) has eigenvalues λ1,λ2,… λ2n.Robust control is necessary for structures due to the inherent modeli...

1998, 30(6): 748-753. doi: 10.6052/0459-1879-1998-6-1995-186

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DISCUSSION ON "APPLICATIONS OF A SECOND-ORDERUPWIND TVD SCHEME TO NONEQUILIBRIUM HYPERSONICFLOWS AROUND BLUNT-BODY

1998, 30(6): 754-756. doi: 10.6052/0459-1879-1998-6-1995-187

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REPLY TO DISCUSSION ON“ APPLICATIONS OF A SECONDORDER UPWIND TVD SCHEME TO NONEQUILIBRIUMHYPERSONIC FLOWS AROUND BLUNT-BODY”

1998, 30(6): 757-760. doi: 10.6052/0459-1879-1998-6-1995-188

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1998 Vol. 30, No. 6

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