ITER屏蔽块前集箱盖板的冷却强化

运用FLUNET软件对ITER屏蔽模块上的前集箱进行了数值模拟计算。计算结果表明,前集箱盖板存在冷却不均匀和冷却不够充分的问题。根据数值模拟的结果,对前集箱中的导流板进行了改进,并给出了改进后导流板的几何尺寸和结构。改进后的数值分析结果表明,采用改进后的T型导流板,前集箱盖板的冷却可以满足ITER的要求。     

利用Cramér-Rao理论研究相位差法的最佳离焦量

针对光子数足够多的情况,利用Cramér-Rao理论研究了在选取离焦作为附加像差时,不同的待测波前和目标对最佳离焦量选取的影响。结果表明:在点目标情况下,像差的大小和空间频率对最佳离焦量的影响不大;而在扩展目标情况下,最佳离焦量虽然与待测像差的空间频率关系不明显,但随着待测像差峰谷值的增大而增大。最佳离焦量与目标的结构有关而与其扩展程度关系不大,成像时目标上各点的干扰越大,最佳离焦量越大。     

具有多个奇点的广义的Liénard系统不存在任何闭轨的条件

本文不同于一般的方法，利用辅助函数建立了具有多个奇点的广义的Ｌｉéｎａｒｄ系统（Ｅ）不存在任何闭轨的若干判别条件，关于（Ｅ）的经典的Ｂｅｎｄｉｘｓｏｎ判别法则和Ｐｏｉｎｃａｒé地形系法则是其特例．此外，给出了包括三次振动系统在内的例子．     

对于局部有界函数的积分型Szász-Bézier算子的逼近估计

引入一种积分型的 Szász- Bézier算子 ,并研究其逼近性质 ,得到了此类算子对局部有界函数的逼近阶估计公式     

Étude numérique de l'écoulement d'un fluide non newtonien thermodépendant entre deux plaques parallèles

In this study, the heat transfer of a non Newtonian thermodependent fluid flowing between two parallel plates is considered. The effects of different parameters on the evolutions of thermal boundary layer and of Nusselt number are numerically investigated in two heating cases and correlations are proposed to compute the heat transfer. To cite this article: N. Van Tuan, M. Lebouche, C. R. Mecanique 333 (2005).     

Prolongation of two phases in the model of fluid displacement through a capillaryProlongement de deux phases dans le modèle du déplacement d'un fluide dans un capillaire

The problem of a piston-like displacement of a fluid by another in a capillary is examined. It is suggested that each fluid is prolonged into the domain occupied by the other fluid. This enables the replacement of the two-phase flow problem by a transient single-phase flow problem, with discontinuity in velocity and pressure on a film interface. The problems related to the triple point are solved by introducing a limit fluid near the pore wall. The demonstration of the Washburn equation contributes to the physical justification of our model. To cite this article: Y. Lucas et al., C. R. Mecanique 334 (2006).     

Transition in plane parallel shear flows heated internallyTransition dans des écoulements cisaillés parallèles chauffés intérieurement

The stability of internally heated inclined plane parallel shear flows is examined numerically for the case of finite value of the Prandtl number, Pr. The transition in a vertical channel has already been studied for 0?Pr?100 with or without the application of an external pressure gradient, where the secondary flow takes the form of travelling waves (TWs) that are spanwise-independent (see works of Nagata and Generalis). In this work, in contrast to work already reported (J. Heat Trans. T. ASME 124 (2002) 635–642), we examine transition where the secondary flow takes the form of longitudinal rolls (LRs), which are independent of the steamwise direction, for Pr=7 and for a specific value of the angle of inclination of the fluid layer without the application of an external pressure gradient. We find possible bifurcation points of the secondary flow by performing a linear stability analysis that determines the neutral curve, where the basic flow, which can have two inflection points, loses stability. The linear stability of the secondary flow against three-dimensional perturbations is also examined numerically for the same value of the angle of inclination by employing Floquet theory. We identify possible bifurcation points for the tertiary flow and show that the bifurcation can be either monotone or oscillatory. To cite this article: M. Nagata, S. Generalis, C. R. Mecanique 332 (2004).     

Espaces d'écoulements dits « universels »Spaces of universal flows

An isochoric motion can be performed both in perfect fluid, in Newtonian fluid, in Maxwell fluid (slow motions) and in Rivlin–Ericksen fluid of second grade whatever be viscosities and viscometric coefficients, iff the motion is universal. Every universal motion with steady vorticity is a generalised Belrami flow, and fulfils the Stokes equation. If the velocity $\text{u}$ of an universal motion complies with $\text{rot}\text{[(?}{}^{\mathrm{<mtext>t</mtext>}}\text{(}\text{Δ}\text{u}\text{))}\text{u}\text{]=}\text{0}$, the motion stands for feasible motion in every second order fluid. Brothers of the potential flows, all the sets of universal motions make up bundles of linear or cono??d spaces with various dimensions, finite or infinite, issued from the rest $\text{u}\text{≡}\text{0}$. The structures appear by scanning parallel to the potential flows. To cite this article: M. Bouthier, C. R. Mecanique 331 (2003).     

Étude tridimensionnelle des contraintes de cisaillement à la paroi dans un tube de section droite non circulaireThree-dimensional study of wall shear stresses in a tube of noncircular cross-section

This paper describes numerical solutions of the Navier–Stokes equations for incompressible steady flow through a rigid smooth straight tube with an axially uniform non-circular cross section which mimics collapsed veins at peculiar values of the transmural pressure. One of the peculiar values of the transmural pressure produces a contact of the opposite walls along a straight segment. This article deals with the space variations of the wall shear stress induced along the wetted perimeter of the cross section as well as in the streamwise direction especially in the entry length. The motivation of this study is to provide the data for experimental works on flow-subjected endothelial cell culture when the space variations of the wall shear stress are non-uniform. To cite this article: S. Naili et al., C. R. Mecanique 330 (2002) 483–490.