水流

Proceeding from the viewpoint of two-phase flow,the Bernoulli equation for silt-laden water flow is derived, which reflects real mechanic characteristics of silt-laden water flow.

从两相流动观点出发，推导了含沙水流时的伯努利方程式，使其更能真实地反映含沙水流的力学特性；对含沙水流条件下水轮机的工作参数进行了定义，进而推出其具体计算方法。

The vane is a technique for river bank protection,which can alter direction of velocity and eliminate observably the centrifugally induced secondary current to reduce concaved bank scour and protrude bank sediment in river curves.

导流板是一种保护冲刷河道河床的技术。它能够改变水流的流向并能显著地减少弯道水流中的次生水流，从而解决了弯道中凹岸冲刷，凸岸淤积的问题。

Because the condition of current drag force of group piles is more complex than that of single pile, it is difficult to solve the problem in theory.

桩群的水流阻力比单桩的水流阻力要复杂的多，理论上解决桩群水流阻力目前还比较困难。

At the time of dealing with the fourth problem, we try calculus of variation of spending, move route transform into a line issue of the victory, Utilize Euler formula , ask and publish time running orbit after a little while most , confirm right route most, It's a pity that we can't get a satisfactory answer in a short time.

得到如下结果：在水流速度不变的情况下，年第一名的游速为，与方向与X轴成，如竞渡者以行进，则与X轴成，用时分秒，竞渡者若与对岸垂直游不可能达到终点；在不同区段内水流速度不变的情况下，竞渡者以折线前进，用时约为；在同一区段内水流速度变化情况下，竞渡者以曲线前进，用时约为。

Based on the theory of tidal flow and sediment motion, a 2-D depth-integrated mathematical model for the Jiaojiang Estuary is developed by using explicit scheme of finite difference on the triangle elements. The results show that the rotary currents occurring in this area can be simply and effectively simulated by the model. Meanwhile, the suspended sediment concentration simulated is in agreement with the field data.

本文根据椒江口实测水文地形资料，从平面二维水流泥沙基本方程和基本理论出发，采用三角单元有限差分法对水流泥沙方程显示求解，对椒江口潮流泥沙进行了数值模拟，模型简单实用，较好地再现了具有旋转潮波性质的椒江河口水流运动特征，含沙量场也得到了基本正确的反映。

For a time, surface and subsurface current are in opposite directions; flow is seaward at the surface and landward near the bottom.

在一个时期，表层和次表层的水流方向相反；表层水流向外海方向流动，靠近底层的水流则向陆地方向流动。

It indicates that emphasis should be put on the following subjects in the future: the determination of field infiltration coefficient and roughness coefficient;the optimal combination of field standard and irrigation technical index ,and the rational ground levelness degree and mode.

对近10多年来地面灌溉水流运动数值模拟方面的国内外研究进展进行了归类整理，并就目前研究中存在的不足和未来急待深入研究的问题进行了探讨，认为在今后的研究中应把地面灌溉入渗参数和糙率的确定问题，不同地区和作物条件下合理的田块尺寸与灌水要素的优化组合研究及经济合理的田间土地平整度及平地模式的研究，长畦分段灌、阶式水平畦灌、覆膜灌溉条件下的水流运动和合理灌水技术指标的研究，浑水灌溉和土壤气阻对地面灌溉水流运动的影响机理研究等作为重点内容。

The experiment shows that negative pressure exists in the roof of pressure tunnel outlet and open channel segment, strong water-wing on sidewall, unstable flow in open channel.

结果表明，原设计方案压力洞出口顶板和明渠段存在负压，侧墙水翅高，明渠中水流不稳，流态差，水流空化数偏低，底空腔偏小，水流掺气能力不足。

The flow conditions in the outlet section of the suction box and in the entrance section of discharge passage are substantially different from those assumed in numerical computation, resulting in notable influence on hydraulic losses and pumping system performance.

研究发现，水泵叶轮旋转和导叶出口剩余环量与进、出水流道的内部流场相互作用，进水流道的出口水流条件和出水流道的进口水流条件与单独计算时的假定有本质不同，对进、出水流道的水力损失和装置性能有显著的影响。

This paper reviews and summarizes the progress in this field as follows: the mathematical model and the difficulty of the analytical solutions is introduced; discusses the latest progress of the numerical solutions is discussed; the finite difference method, the Godunov method, the Boltzmann method, and the KFVS method of one-dimensional dam-break problem are introduced; the TVD method, the discontinuous finite element method, the finite volume method and characteristic method of two-dimensional dam-break problem are discussed; the applicability, the advantage and the disadvantage of each method are analyzed; and the progress in the numerical calculations of flow of fluid with free surface are presented.

回顾和总结了国内外对溃坝水流演进问题的研究进展：介绍了溃坝水流的数学模型及解析解法存在的困难，进而讨论了数值解法的最新进展；论述了求解溃坝水流一维问题的有限差分法、近似黎曼解的Godunov格式法、Boltzmann法、KFVS法和二维问题的TVD格式法、间断有限元法、有限体积法、特征线法，并分析了各种方法的适用范围和优缺点，及讨论了限制函数的使用；介绍了利用自由水面追踪方法计算溃坝水流的研究进展，并根据目前存在的不足和实际工程的需要，提出了进一步研究的方向和发展趋势。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了