Numerical simulation of the flow field in a thermal plasma reactor

A numerical simulation is presented for a thermal plasma reactor with particle-trajectory model in this paper.Turbulance is considered by using simple SGS model.Thegoverning equations are solved by means of the algorithm of SIMPLER.The calculatedresults give the velocity and the temperature fields within plasma reactor,and thetrajectories of the injected particles.     

A new higher-order theory to laminated plates and shells

In this paper a new higher-order theory to laminated plates and shells is presented and then Symmetric and antisymmetric cross-ply laminated plates, cylindrie bending and bending of spherical shells are also studied. In order to examine the accuracy of the theory, several particular examples have been calculated. The numerical results are in good agreement with the exact solution, which shows the theory is possessed of higher accuracy and is easy to solve a problem with few unknowns.     

第4届国际物理学中的非线性与湍流过程专题讨论会(IWNTPP-4)

<正> 1 一般情况 由国际纯粹与应用物理联合会(IUPAP)委托苏联科学院主办两年一次的国际“物理学中的非线性与湍流过程”专题讨论会(IWNTPP),这次是第4届,于1989年10月9—22日在苏联的基辅举行.按照IWNTPP的惯例,除苏联学者外,会议的参加者必须是得到苏联科学院的邀请的.这次会议参加者共476人.苏联派出以5位院士为首的强大阵容代表苏联科学院朗道理论物理研究所、空间研究所、复杂问题“控制论”科学委员会,乌克兰科学      

湍流运动与非线性科学理论

本文较系统地介绍了近３０年来非线性科学理论的发展对湍流运动研究的贡献．它所涵盖的内容涉及到了当前非线性科学理论的大部分热点．从这里,可以隐约地看到一个正在形成中的湍流运动新理论的框架．      

在我国开展工程湍流研究的设想

本文包括三部分:１）提出开展工程湍流研究的背景;２）工程湍流研究的特征和内容;３）开展工程湍流研究的设想,其中包括:ａ）湍流理论的概念鉴别和在工程中的应用,ｂ）湍流模式理论的应用和完善,ｃ）湍流测量和ｄ）湍流控制．      

Vertical rotation effect on turbulence characteristics in an open channel flow

This paper solves the three-dimensional Navier-Stokes equation by a fractional-step method with the Reynolds number Reτ=194 and the rotation number Nτ=0-0.12. When Nτ is less than 0.06, the turbulence statistics relevant to the spanwise velocity fluctuation are enhanced, but other statistics are suppressed. When Nτ is larger than 0.06, all the turbulence statistics decrease significantly. Reynolds stress budgets elucidate that turbulence kinetic energy in the vertical direction is transferred into the streamwise and spanwise directions. The flow structures exhibit that the bursting processes near the bottom wall are ejected toward the free surface. Evident change of near-surface streak structures of the velocity fluctuations are revealed.     

Expressions for pressure-velocity-gradient correlations

The term for pressure-velocity-gradient correlation was initiated by Rott’srewriting the correlation between the pressure fluctuation gradient and velocity fluctuation.However,it is very difficult to consider the effect of this term.Since Rotta’s work,Launderet al.has made some estimates of this term.In this paper according to the equations forvelocity fluctuation,the pressure fluctuation is solved so that the average value of theproduct of the pressure fluctuation and the velocity fluctuation gradient is obtained.Thus,the whole expressions for the pressure-velocity-gradient correlation are derived.The resultexplains that the limited expressions by Rotta and Launder are reasonable to a certaindegree.The whole expressions in this paper are discussed respectively in two situations:oneis without a separate consideration of large and small vortexes;the other is with a separateconsideration of three kinds of vortexes.Therefore,the paper gives the whole expressions forpressure-velocity-gradient correlation     

Note on the critical variational state in elasticity theory

Recently Prof. Chien Wei-zang pointed out that in certain cases, by means of ordinary Lagrange multiplier method, some of undetermined Lagrange multipliers may turn out to be zero during variation. This is a critical state of variation. In this critical state, the corresponding variational constraint can not be eliminated by means of simple Lagrange multiplier method. This is indeed the case when one tries to eliminate the constraint condition of strain-stress relation in variational principle of minimum complementary energy by the method of Lagrange multiplier.By means of Lagrange multiplier method, one can only derive, from minimum complementary energy principle, the Hellinger-Reissner Principle, in which only two type of in-dependent variables, stresses and displacements, exist in the new functional. Hence Prof. Chien introduced the high-order Lagrang multiplier method bu adding the quadratic terms.to original functions. The purpose of this paper is to show that by adding to original functionals one     

Generalized variational principles with several arbitrary parameters and the variable substitution and multiplier method

The functional transformations of variational principles in elasticity are classified as three patterns: Ⅰ relaxation pattern, Ⅱ augmented pattern and III equivalent pattern.On the basis of pattern Ⅲ, the generalized variational principles with several arbitrary parameters are formulated and their functionals are defined. They are: the generalized principle of single variable u with several parameters, the generalized principle of two variables u, σ with several parameters, the generalized principle of two variables u, ε with several parameters, and the generalized principle of three veriables u, ε, σ with several parameters. From these principles, a series of new forms of equivalent functionals can be obtained. When the values of these parameters are properly chosen, a series of finite element models can be formulated.In this paper, the question of losing effectiveness for Lagrange multiplier method is also discussed. In order to "recover" effectiveness for multiplier method, a modified method, namely, the variable substitution and multiplier method, is proposed.     

Photoviscoelasticity—An experimental method in viscoelastic stress analysis

In this paper, the photoviscoelasticity method of viscoelastic stress analysis has been discussed in detail.lt is shown that,in order to avoid the effects of shrinkage andaging in the test specimens, it is suggested that the specimens should be tempered for three days at a temperature of 60℃ before starting the experiments, and the temperature filtering arrangement is recommended in the experimental setups to keep the temperature absolutely constant. Besides the axi-symmetrical time-dependent stress state, the determination of the principle axes of the refraction tensor experimentally remains an unsufficiently solved problem. To avoid dynamic effect in the step wise loading, the time of measurement in every step should be limited in about one secend.