共查询到20条相似文献,搜索用时 46 毫秒
1.
Yves P. Marx 《国际流体数值方法杂志》1991,13(6):775-796
An upwind MUSCL-type implicit scheme for the three-dimensional Navier-Stokes equations is presented and details on the implementation for three-dimensional flows of a ‘diagonal’ upwind implicit operator are developed. Turbulence models for separated flows are also described with an emphasis on the numerical specificities of the Johnson-King non-equilibrium model. Good predictions of separated two- and three-dimensional flows are demonstrated. 相似文献
2.
Methods and results of studies of the three-dimensional viscoplastic stress–strain state of engineering structures under thermomechanical loading are presented. The following classes of thermoviscoplastic problems are considered: axisymmetric problems, nonaxisymmetric problems for bodies of revolution, three-dimensional problems for bodies of arbitrary shapes, and three-dimensional problems for anisotropic bodies of revolution 相似文献
3.
Hui Pih 《Experimental Mechanics》1980,20(12):437-444
The theories of the birefringent flow are reviewed. The development of the experimental techniques, the search for suitable birefringent fluids, and the application of the method to various engineering problems are presented. The special scattered-light polariscope for the three-dimensional birefringent flow and the research to establish the three-dimensional flow-optic law are discussed. A few examples of three-dimensional flow through straight channels with various cross sections are given. 相似文献
4.
《应用数学和力学(英文版)》2017,(9)
Boundary-layer receptivity is always a hot issue in laminar-turbulent transition. Most actual laminar-turbulent transitions belong to three-dimensional flows. An infinite back-swept flat-plate boundary layer is a typical three-dimensional flow. Study of its receptivity is important both in theory and applications. In this paper, a freestream turbulence model is established. A modified fourth-order Runge-Kutta scheme is used for time marching, and compact finite difference schemes are used for space discretization. On these bases, whether unsteady cross-flow vortices can be excited in the three-dimensional boundary layer(the infinite back-swept flat-plate boundary layer) by free-stream turbulence is studied numerically. If so, effects of the level and the direction of free-stream turbulence on the three-dimensional boundary-layer receptivity are further studied. Differences of the three-dimensional boundary-layer receptivity are then discussed by considering the non-parallel effect, influence of the leading-edge stagnation point of the flat plate, and variation of the back-swept angle separately. Intensive studies on the three-dimensional boundary-layer receptivity will benefit the development of the hydrodynamic stability theory, and provide a theoretical basis for prediction and control of laminar-turbulent transition. 相似文献
5.
6.
本文提出了固支复合材料各向异性层合圆板受均布横向载荷作用下的满足三维弹性力学基本微分方程和边界条件的解析解答。文中采用一种发展的摄动方法进行求解,板中的每个应力和位移都展开为无量纲厚度参数ε的摄动级数,并采用二维板理论解答作为其相应三维摄动解答的一个基本解的形式,通过摄动方法逐级求解而获得完整的三维解答。文中以解析形式和数值形式给出了高精确度的三维应力和位移结果,结果表明,本文求解三维问题的解析方法是合理有效的。 相似文献
7.
8.
David J. Steigmann 《International Journal of Non》2007,42(2):233-240
Non-linear plate theory for thin prismatic elastic bodies is obtained by estimating the total three-dimensional strain energy generated in response to a given deformation in terms of the small plate thickness. The Euler equations for the estimate of the energy are regarded as the equilibrium equations for the thin plate. Included among them are algebraic formulae connecting the gradients of the midsurface deformation to the through-thickness derivatives of the three-dimensional deformation. These are solvable provided that the three-dimensional strain energy is strongly elliptic at equilibrium. This framework yields restrictions of the Kirchhoff-Love type that are usually imposed as constraints in alternative formulations. In the present approach they emerge as consequences of the stationarity of the energy without the need for any a priori restrictions on the three-dimensional deformation apart from a certain degree of differentiability in the direction normal to the plate. 相似文献
9.
NONLINEARTHREE-DIMENSIONALANALYSISOFCOMPOSITELAMINATEDPLATES¥(江晓禹,张相周,陈百屏)JiangXiaoyu;(SouthwesternJiaotongUniversity,Chengdu6... 相似文献
10.
An effective approximate technique for calculating heat transfer, viscous stress, and species components on the windward side of three-dimensional bodies at incidence in hypersonic flow is developed. Using the similarity method, the solution of the three-dimensional problem is reduced to the solution of an axisymmetric problem. For determining the heat flux on a real body, modified two-dimensional equations are solved for equivalent axisymmetric bodies, specially constructed for meridional planes of the original body. For an arbitrary three-dimensional geometry and angle of attack formulas are derived and a conversion program is developed. These make it possible to determine all the parameters of the equivalent body corresponding to a given meridional plane of the original body; then these parameters are used as input data for calculating the viscous flow past the body. The solutions of the two-dimensional equations for the equivalent bodies are in good agreement with more exact solutions of the three-dimensional equations. 相似文献
11.
In this paper, new nonlinear dynamic formulations for belt drives based on the three-dimensional absolute nodal coordinate formulation are developed. Two large deformation three-dimensional finite elements are used to develop two different belt-drive models
that have different numbers of degrees of freedom and different modes of deformation. Both three-dimensional finite elements
are based on a nonlinear elasticity theory that accounts for geometric nonlinearities due to large deformation and rotations.
The first element is a thin-plate element that is based on the Kirchhoff plate assumptions and captures both membrane and bending stiffness effects. The other three-dimensional
element used in this investigation is a cable element obtained from a more general three-dimensional beam element by eliminating degrees of freedom which are not significant in
some cable and belt applications. Both finite elements used in this investigation allow for systematic inclusion or exclusion
of the bending stiffness, thereby enabling systematic examination of the effect of bending on the nonlinear dynamics of belt
drives. The finite-element formulations developed in this paper are implemented in a general purpose three-dimensional flexible
multibody algorithm that allows for developing more detailed models of mechanical systems that include belt drives subject
to general loading conditions, nonlinear algebraic constraints, and arbitrary large displacements. The use of the formulations
developed in this investigation is demonstrated using two-roller belt-drive system. The results obtained using the two finite-element
formulations are compared and the convergence of the two finite-element solutions is examined. 相似文献
12.
13.
An automated quasi three-dimensional finite element grid generation method is presented for particular three-dimensional complex connected domain, across which some are simply connected two-dimensional.regions and some are multiply connected two-dimensional regions. A subdivision algorithm based on the variational principle has been developed to ascertain the smoothness and orthogonality of the generated grid in any cross sections. Smooth transition between the simply and multiply connected regions is maintained. For illustration, the method is applied to generate a finite element three-dimensional grid for human above knee stump. 相似文献
14.
陈至达 《应用数学和力学(英文版)》1984,5(5):1581-1585
Various exprressions of three-dimensional J integral are proposed. We derive here three-dimensional J integral by means of general potential energy principle and Green's theomem. Its physical meaning and application are shown in the paper, the results are true both for infinitesimal and finite deformation. 相似文献
15.
A three-dimensional enriched finite-element methodology is presented to compute stress intensity factors for three-dimensional cracks contained in functionally graded materials (FGMs). A general-purpose 3D finite-element based fracture analysis program, FRAC3D, is enhanced to include this capability. First, using available solutions from the literature, comparisons have been made in terms of stresses under different loading conditions, such as uniform tensile, bending and thermal loads. Mesh refinement studies are also performed. The fracture solutions are obtained for edge cracks in an FGM strip and surface cracks in a finite-thickness FGM plate and compared with existing solutions in the literature. Further analyses are performed to study the behavior of stress intensity factor near the free surface where crack front terminates. It is shown that three-dimensional enriched finite elements provide accurate and efficient fracture solutions for three-dimensional cracks contained in functionally graded materials. 相似文献
16.
IntroductionNumerical manifold method is a new numerical method established on the basis of finitecover of manifold[1,2].By using continuous and non-continuous finite cover system,thenumerical manifold method includes the continuous and non-continuous as … 相似文献
17.
本文利用三台照相机系统记录三维射流的流动,通过照相机系统的标定、三维空间粒子的重构、空间粒子的对应及误对应向量的判断和消除等,建立了一种三个图像记录设备组成的三维PIV图像处理算法,并对其精度进行了分析,通过对三维射流图像的处理和分析表明,该方法是切实可行的。 相似文献
18.
A numerical method of calculating a three-dimensional laminar supersonic underexpanded jet escaping into an accompanying supersonic flow is developed. The simplified Navier-Stokes equations for a steady-state three-dimensional flow are employed. Numerical calculations are carried out for several cases relating the outflow of jets from a four-nozzle assembly into an accompanying supersonic flow, and a number of the characteristics of three-dimensional flows of this kind are presented.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 88–93, November–December, 1972. 相似文献
19.
An efficient reduced-order modeling to analyze three-dimensional unsteady partial cavity flows is proposed. The proposed approach is based on the boundary element method along with the potential flow assumption. To this end, a novel non-iterative method based on the flow eigenmodes of three-dimensional partial cavity flows is applied. Eigenanalysis and reduced-order modeling for unsteady flows over a three-dimensional hydrofoil with various sections are performed. The results obtained from the present analysis are compared with those reported in the literature to verify the strength of the proposed approach. In order to examine the performance of the introduced algorithm for unsteady cavitating flows, various simulations for several reduced frequencies, hydrofoil geometries and different cavitation numbers are also investigated. Comparison between the obtained results using the novel and conventional methods indicates that the present algorithm works very well with sufficient accuracy. Moreover, it is shown that the proposed method is computationally more efficient than the conventional ones for unsteady sheet cavitation analysis on three-dimensional hydrofoils. 相似文献
20.
三维双材料结构的应力奇异性分析 总被引:1,自引:1,他引:1
应用有限单元法子模型技术,对具有不同界面角的三维双材料结构的应力奇异性进行了分析。结果表明,应用子模型技术估算三维双材料结构的应力奇异性指数是有效的。然后分析了界面端线和界面端点处附近奇异性指数,得到了一些重要而有趣的结果。最后对消除三维双材料结构应力奇异性的几何条件进行了讨论。 相似文献