共查询到20条相似文献，搜索用时 187 毫秒
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本文以城市地表与明渠河道水流运动为主要模拟对象。研制了模拟城市暴雨内涝积水的数学模型。模型以平面二维非恒定流的基本方程和无结构不规则网格划分技术为骨架,应用了一维非恒定流方程的算法。采用分类简化处理的方法,将通道分为河道型、路面型、特殊通道型（城市内的二级河道）网格,研究城市面雨量的计算方法以及数学模型在哈尔滨市的应用情况和误差分析。 相似文献
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针对目前过冷水制取流态冰的方法常会碰到冰堵并且极度依赖电能的问题,提出了一种新的流态冰制取方法.新方法主要包括2个部分：蒸发式过冷过程和溶液除湿过程.对蒸发式过冷过程进行了理论研究,通过影响因子的引入改进了经典的扩散-控制模型;同时,对蒸发式过冷过程进行了实验研究,用粒子分析仪测量水滴的粒径与速度,用红外热像仪测量蒸发过冷过程的温度场.研究结果表明：改进的理论模型所得出的结果与实验结果吻合得很好.另外,通过与传统过冷水制取流态冰方法的比较发现,新方法可以回收利用自身排出的废热,降低了对电能的依赖,提高了制流态冰的效率,从而使系统的整体性能得到改善. 相似文献
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一、水力学课堂教学改革1.改革课堂教学内容在多年的教学实践中,我们深切体会到教学大纲是课程设置的准则,必须贯彻到教学过程始终。但大纲并不是固定不变的条文,随着学科的发展,结合教改实践,也应对课程教学内容进行更新和优化,以便在有限的学时内高质量地完成教学任务。消枝强干,重组教学内容。我们删掉了偏于专业课讲述的内容,保证“三元流”及“三大方程”等水力学最基本的内容有足够的讲授课时;对专业基础内容,进行重新整合,如将管道非恒定流的部分内容与管道恒定流的内容进行整合、明渠非恒定流与明渠恒定非均匀流进行整合。讲课时,使… 相似文献
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本建立了一维数值模型来模拟顺直冲积渠道的冲刷过程．模型考虑了床沙的非均匀性、床面形态变化，应用该模型预测计算了冲刷过程中的床沙级配变化．模型计算结果表明床沙粗化过程不仅与水流的水力特性有关，还与床沙的颗粒大小及分布有关．模型计算结果与2组非均匀床沙水槽试验结果进行了比较，结果表明模型计算结果与试验结果符合得较好． 相似文献
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径向集体流是高能重离子碰撞物理学研究中十分重要的实验可观测量,它能够把碰撞过程中压缩和膨胀阶段的部分信息带到碰撞的末态,通过对径向流的分析可还原碰撞过程中的信息。 相似文献
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通过在某中心渔港工程中采用振冲碎石桩工艺对软地基进行加固的施工进行系统的总结。对比振冲碎石桩在道路、建筑等工程中的应用有诸多不同,在施工工艺、质量控制、加固效果检验有其独特之处,介绍振冲碎石桩在水工港口工程软地基处理的工艺原理、工艺流流程、质量控制的方法及效果、采用重型动力触探试验进行检测的方法及结果。 相似文献
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曾鸿能 《中山大学学报论丛》1993,(2)
本文用Stone-Brian隐式有限差分方法,结合实例对恒定非均匀流污染带计算,进行数值试验。认为方法切实可行,较之解析解有其显著优点,文中就计算及程序设计提出了应注意的问题. 相似文献
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采用计算流体力学领域中的新技术建立了双戗堤进占截流的数学模型 .用适体坐标技术克服天然河道复杂的几何边界给有限差分法所带来的困难 ;用交替方向隐式有限差分格式求解变换平面上的偏微分方程 ;用动边界技术处理河床的淹露 .该模型已用于预测三峡工程截流过程中的水力特性 ,计算结果与实验数据吻合较好 相似文献
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针对沙棘植物“柔性坝”的拦粗淤细作用,结合黄河粗沙区沟道侵蚀及泥沙输移的规律,开展了这方面的机理研究及野外拦沙保水试验,推导了沙棘植物柔性坝前壅水计算迭代公式．分析结果表明,沙棘植物坝具有良好的拦沙阻水作用,起到了滞流和增大入渗的作用;“柔性坝”可显著调节沟道土壤水分,提高水源涵养能力,对发展沟头林业和沟坡农业生产打下良好基础,而且可实现水沙分治． 相似文献
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Vertical distribution of sediment concentration 总被引：1，自引：0，他引：1
A simple formula is proposed to predict the vertical distribution of a suspended load concentration in a 2D steady turbulent flow. The proposed formula significantly improves the well-known Rouse formula where sediment concentration has an infinitely large value at the channel bottom and a zero value at the water surface. Based on this formula and the logarithmic velocity profile, a theoretical elementary function for the transport rate of a suspended load is developed. This equation improves the Einstein equation in which the unit-width suspended sediment discharge must be solved by numerical integration and a contradiction between the lower limit of the integral and that of velocity distribution exists. 相似文献
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A model for incipient movement of sediment in rolling pattern was established. In this model, the starting of sediment particles under low transport rate, the exposure degree of sediment, the lateral slope of water surface and the effect of transverse circulating current induced by the hydraulic structure of bend flow were fully considered. A theoretical formula for the incipient velocity of non-cohesive and non-uniform sediment in sloping river bends was developed. The results from the theoretical formula compared well with the experimental data. 相似文献
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For a channel-shoal system in a funnel-shaped basin the impact of dredging and dumping is investigated using a complex process-based
model. First, the residual flow and sediment transport circulations are analysed for the channel-shoal pattern, which has
emerged after a long-term model simulation. Results are compared to the Western Scheldt estuary, which forms the inspiration
for this study. Subsequently, different dredge and dump scenarios are modelled, according to a conceptual model, in which
ebb-and flood-channels and enclosed shoals form morphodynamic units (cells) with their own sediment circulation. Model results
show that dumping sediment in a channel further reduces the channel depth and induces erosion in the opposite channel, which
enhances tilting of the cross-section of the cell and eventually can lead to the degeneration of a multiple channel system
into a single channel. The impact of different dredging and dumping cases agrees with results from a stability analysis. This
means that this type of model applied to a realistic geometry can potentially be used for better prediction of the impact
of human interventions. 相似文献
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秦国刚 《杨凌职业技术学院学报》2009,8(4):60-63
大顶子山船闸上下游隔流堤、靠船墩均为抛石基床结构,抛石11万m^3,其中水下6．7万m^3。水下抛石高差难控制,抛石夯实质量不易保障,基床粗平和细平的平整度控制难度大。通过夯实试验,摸索出一整套基床整平的施工技术,解决了水下抛石基床施工质量控制等难题．并总结出一整套水下抛石基床施工技术并积累了经验。 相似文献
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王新奇 《西安文理学院学报》2010,13(1):73-75
通过野外水流试验,研究了植物坝坝前壅水以及对水流流态的影响．结果表明,沟道柔性坝系普遍发生了淤积,引起上游水位壅高,水流流速减小．减缓了沟道土壤水分蒸发,增大土壤入渗,达到拦沙保水的目的． 相似文献
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郭俊克 《天津大学学报(英文版)》2009,15(2):79-94
Bridge pressure flow scour at clear water threshold condition is studied theoretically and experimentally. The flume experiments reveal that the measured scour profiles under a bridge are more or less 2-dimensional; all the measured scour profiles can be described by two similarity equations, where the horizontal distance is scaled by the deck width while the local scour by the maximum scour depth; the maximum scour position is located just under the bridge about 15% deck width from the downstream deck edge; the scour begins at about one deck width upstream the bridge while the deposition occurs at about 2.5 deck widths downstream the bridge; and the maximum scour depth decreases with increas-ing sediment size, but increases with deck inundation. The theoretical analysis shows that: bridge scour can be divided into three cases, i.e. downstream unsubmerged, partially submerged, and totally submerged. For downstream unsubmerged flows, the maximum bridge scour depth is an open-channel problem where the conventional methods in terms of critical velocity or bed shear stress can be applied; for partially and totally submerged flows, the equilibrium maximum scour depth can be described by a scour and an inundation similarity number, which has been confirmed by experiments with two decks and two sediment sizes. For application, a design and field evaluation procedure with examples is presented, including the maximum scour depth and scour profile. 相似文献
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CHANSONHubert GONZALEZCarlosA. 《浙江大学学报(A卷英文版)》2005,6(3):243-250
INTRODUCTION The stepped channel design has been used fomore than 3500 years. Greek and Minoan engineerswere probably the first to design an overflow steppedweir and stepped storm waterways respectively(Chanson, 2001). Later, Roman, Moslem, Mughaand Spanish designers used a similar technique. Thesteps increase significantly the rate of energy dissipation taking place on the channel face, reducing thesize of the required downstream energy dissipationand the risks of scouring. Rec… 相似文献
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黄河下游河道逐年淤积抬高，河道断面萎缩，过流能力降低，漫滩流量大幅度减小，致使黄河洪水出现小流量、高水位、大险情的特点．通过对黄河下游的泥沙淤积规律的认识，以黄河下游洪水不同时期水位的变化、洪水传播时间的变化以及漫滩流量和削峰作用的变化来论述下游河道淤积对洪水特性的影响． 相似文献