力学学报

ON THE THEORETICAL BASE OF VISCOUS SHOCK LAYER EQUATIONS AND THE FURTHER DEVELOPMENTS

In the present paper, the method of matched asymptotic expansions is introduced to the Davis' viscous shock layer theory, and the result of the first order of approximation leads to the same hypersonic chemically reacting viscous shock layer equations as with the Davis' method. Although the resulting equations are the same, the fundamental assumptions of the latter method is more restricteived. The result of the second order approximation given for me first time in the present paper leads to a theoretical m...

1992, 24(1): 1-8. doi: 10.6052/0459-1879-1992-1-1995-704

PDF

ON THE THEORETICAL BASE OF VISCOUS SHOCK LAYER EQUATIONS AND THE FURTHER DEVELOPMENTS

In this paper, using the reductive perturbation method combined with thePLK method and two-parameter expansion procedure, we treat the problem of head-on colli sion between two solitary waves described by the generalized Korteweg-de Vries equation (the gKdV equation) and obtain its second-order approximate solution. The results show that after the collision, the gKdV solitary waves preserve their profiles and during the collision, the maximal amplitude is the linear superposition of the maximal amplitudes o...

1992, 24(1): 9-18. doi: 10.6052/0459-1879-1992-1-1995-705

PDF

APPLICATION OF CAPACITANCE MATRIX METHOD IN VORTEX METHOD

A fast vortex method for solving complex irregualr regions is developedin the present paper, using combination of capacitance matrix technique(CMT), fast Fourier transforms (FFT) as well as vortex-in-cell method (VIC). Using this fast solver, separated flows about a plat flate normal to incoming flow with any thickness and a wedge are, impulsed or accelerated motion from rest, computed at high Reynolds numbers. Expecially, the fine field patterns are obtained around the plat flate flow. Due to Kelvin-Helmho...

1992, 24(1): 19-25. doi: 10.6052/0459-1879-1992-1-1995-706

PDF

UNSTEADY INTERACTION OF SHOCK WAVE DIFFRACTING AROUND A CIRCULAR CYLINDER IN AIR

The reflection and diffraction of a planar shock wave around a circularcylinder is a typical problem of the complex nonlinear shock wave phenomena in literature. It has long been studied experimentally, analytically as well as numerically. Takayama in 1987 obtained clear experimental pictures of isopycnics in shock tube under the condition that the impinging shock wave propagates as far as 3 diameters away from the cylinder. To know more completely the whole unsteady process, it is desirable to get experime...

1992, 24(1): 26-31. doi: 10.6052/0459-1879-1992-1-1995-707

PDF

SYMMETRIC BIFURCATION OF STOKES WATER WAVES

Using the fourth-order Zakharov equation the theory of bifurcation by Sa-ffman & Yuen is extended to include the case where the modulation wavelength (p,q) = 0(1). Reasonable three-dimensional symmetrical wave patterns bifurcated from Stokes waves are obtained, and are in good agreement with those given by numerical results by Mclean (1982). Both critical amplitude and modulation wavelength are calculated. They are also close to the experimental data by Su (1981).

1992, 24(1): 32-39. doi: 10.6052/0459-1879-1992-1-1995-708

PDF

LASER SPECKLE MOVEMENT CAUSED BY SURFACE DEFORMATION AND LIGHT WAVELENGTHCHANGE

When a surface is illuminated by laser, the field of diffusing reflectivelight can be described by Fresnel-Kirchhoff integration in the region of Fersnel. If the correlation, before and after the change of intensity field, is analysed by statistical method, three governing equations for variance of intensity field and speckle movement formula can be obtained. In these equations.the surface motion, deformation and wavelength change are all considered to cause the speckle movement.

1992, 24(1): 40-47. doi: 10.6052/0459-1879-1992-1-1995-709

PDF

A NEW PHONOMENON OF ACOUSTIC STREAMING

This paper describes a new phenomenon of acoustic streaming, which ta-kes place when a Helmholtz resonator is excited by an inside sound source with resonant frequency, and takes the form of a turbulent jet. Flow visualizations, hot wire measurements and LDV measurements were applied to investigate the streaming process. It is found that the streaming is forced by the action of Reynolds stress.

1992, 24(1): 48-54. doi: 10.6052/0459-1879-1992-1-1995-710

PDF

CENTROSYMMETRIC CHAOS

1992, 24(1): 55-58. doi: 10.6052/0459-1879-1992-1-1995-711

PDF

ON TOPOLOGY OPTIMIZATION OF TRUSSES WITH MULTIPLE LOADING CONDITIONS AND BE-HAVIOUR CONSTRAINTS

A topology optimization method for truss structures is described in this paper. In this method, the member forces are considered as design variables and the structural weight as objective function. Three main advantages, compared with the prevailing methods, existed in the method. Firstly, the introduction of new design variables makes that not only the main difficulty of pregiven displacement field is warded off but it is more easily for the constraints such as stress and displacement to be dealt with duri...

1992, 24(1): 59-70. doi: 10.6052/0459-1879-1992-1-1995-712

PDF

APPLICATION OF FRACTURE MECHANICS AND BEM TO STRAIN LOCALIZATION PROBLEMS IN A FINITE BODY

The microslip model is a new approach to the mechanism of strain localization in sand deformation. As an extension of the previous study [Mechanics of Materials 8 (1989)89-102] , the paper presents a mathematical formulation of the microslip model with boundary constraints, based on the method of pseudo-tractions and the boundary element methol. Special attention is given to the effect of boundaries on strain localization. Some interesting aspects of the problem, such as the dependence of the deformation ch...

1992, 24(1): 71-81. doi: 10.6052/0459-1879-1992-1-1995-713

PDF

THE BUCKLING AND POST-BUCKLING OF SIMPLY-SUPPORTED RECTANGULAR PLATES UNDER COMBINATIONLOADS

The buckling and post-buckling behaviour of simply-supported ortho-tropic rectangular plates subjected to compressive forces along two opposite edges in the mid-plane is studied in this paper. The stability region of the load is obtained and it is shown that the critical load is at most double. By using the perturbation method with double parameters the asymptotic solution of the buckled state near the critical load is given, the possible buckled states and the dependence of them on parameters are analysed ...

1992, 24(1): 82-92. doi: 10.6052/0459-1879-1992-1-1995-714

PDF

A THEORETICAL SOLUTION FOR AXIALLY SYMMETRIC PROBLEMS IN ELASTODYNAMICS

The paper presents a theoretical solution for the basic equation of axial-ly symmetric problems in elastodynamics. The solution consists of a quasi-static solution which meets inhomogeneous boundary conditions and a dynamic solution which meets homogenerous boundary conditions. After the quasi-static solution has been solved, an inhomogenerous equation on dynamic solution is found from the basic equation. By making use of eigenvalue problem of homogenerous equation, the finite Hankel transform is defind. Th...

1992, 24(1): 93-101. doi: 10.6052/0459-1879-1992-1-1995-715

PDF

APPLICATION OF TENSOR EQUATIONS IN COMPUTATION OF THREE DIMENSIONAL VISCOUS FLOW

The tensor viscous shock-layer equations are used for computing thehypersonic viscous flow over sphere-cone and ellipsoid-cone with angle of attack. The results show that the method can be applied to compute the flow over a complex geometry. The none-quilibriurn chemical reactions of hypersonic flow are considered, the chemical reactions are assumed to proceed at finite rate.

1992, 24(1): 102-108. doi: 10.6052/0459-1879-1992-1-1995-716

PDF

ODE TECHNIQUES AND APPLICATIONS IN COMPUTATIONAL MECHANICS

The rapid advances of new computational technology in solution of ordinary differential equation (ODE) boundary value problems (BVPs) have made a number of high-quality general-purpose ODE solvers well available, but various ODE problems arising in scientific and engineering applications are frequently not in the 'standard' forms for these codes to accept. However, many problems can be transformed into such forms by using some simple and novel conversion techniques. In this paper, a number of ODE conversion...

1992, 24(1): 109-115. doi: 10.6052/0459-1879-1992-1-1995-717

PDF

ANALYTICAL SOLUTION FOR THE UNSTEADY FLOW OF MAXWELL FLUIDS THROUGH ANNULAR PIPES

This paper presents analytical solutions to the partial differentical equation for unsteady flow of Maxwell fluids in annular pipes by using the integral transform method. The results can be used to analyse the behavior of axial velocity and shear stress for unsteady flow of non-Newtonian Maxwell fluids in annular pipes and to provide a theoretical base for pipeline engineering design.

1992, 24(1): 116-121. doi: 10.6052/0459-1879-1992-1-1995-718

PDF

THE BASIC EQUATIONS FOR SUSPENSION FLOWS DERIVED THROUGH A NEW METHOD

This paper presents a new method, with which a set of basic equations forsuspension flows is developed based on the conservation principles of mass, momentum and energy through a quite rigorous derivation. The equations are more practical and easily understood and acceptable since their form is simpler and the quantities in them have concise physi-cal meaning.

1992, 24(1): 122-128. doi: 10.6052/0459-1879-1992-1-1995-719

PDF

1992 Vol. 24, No. 1

NoticeMORE+

Exquisite ArticlesMORE+

Download Center

Author Center