长江口北支围垦对其水动力影响的数值模拟分析

20世纪50年代以来,上海市和江苏省两地对长江口北支实施了大规模围垦,使北支河宽大幅度缩窄,地形边界显著改变。在利用MIKE21_FM构建长江口—杭州湾二维垂向平均潮流数学模型,并用实测数据对模型进行验证的基础上,对北支大规模围垦前后的潮流场进行了模拟分析。研究结果表明：大规模围垦后,北支全河段平均高潮潮位抬升,平均低潮潮位降低;中上游河段涨、落潮流速增大,下游入海河段涨、落潮流速减小;南北支涨潮流汇流点上提至南北支交汇的崇头,涨潮动力增强。     

THREE-DIMENSIONAL NUMERICAL MODELLING OF THE WAVE-IN- DUCED RIP CURRENTS UNDER IRREGULAR BATHYMETRY

A process-based 3-D hydrodynamic model is established to simulate the rip current structures under irregular bathymetry.The depth-varying wave-induced residual momentum,the surface rollers,the turbulent mixing and the wave-current interactions are considered.Experimental datasets are used to validate the model,and it is shown that the model can effectively describe the 3-D structures of the rip currents in both normal and oblique wave incident cases.The flow patterns of the rip currents see various characteristics for different incident wave directions.In the normal incident case,pairs of counter-rotating primary circulation cells are formed,and an offshore rip flow occurs in the embayment troughs.The peak seaward velocities occur at the top of the bed boundary layer,and the undertow is incorporated in addition to the rip currents.In the oblique incident case,the longshore currents are dominant,which result in a meandering flow along the depth contour,and the undertow is weaker compared to that in the normal incident condition.     

基于WCF的网络聊天应用程序

通过介绍WCF通信模型,向大家展示定义和实现WCF服务,并何构建面向服务的应用程序,构建一个简单的网络聊天应用程序详细说明了编写客户端-服务端应用程序的步骤,并且让大家了解WCF框架的强大。     

库区交汇河段纵向淤积形态分析

库区交汇河段受坝前水位升降与干支流流量丰枯的影响,其侵蚀基面具有双重变化特性,从而产生特殊淤积形态。基于大量实测资料,对库区交汇河段干流与支流河道纵向淤积形态进行分类,提出支流纵剖面倒坡锥体淤积与锥体—倒坡锥体过渡淤积两种特殊类型。从水库运行方式与干、支流顶托两个关键因素入手,将水动力条件的变化与干、支流淤积形态建立联系,指出双重顶托的存在为库区交汇河段淤积形态差异的内在机理。     

Research of dynamic scheduling method for the air-to-ground warfare simulation system based on grid

The military field has been a strong demand for automatic management of the running of simulation, and the sharing of simulation resources and so on. Aimed at the puzzles in current HLA-based simulation system, and with the combination of a new grid idea, a framework of simulation grid has been presented. This article is absorbed in the aim how to schedule the task under simulation grid environment and explore the dynamic dispatch to the parallel tasks in the federation entity level. Finally a mended heuristic scheduling algorithm has been designed. This algorithm dynamically adjusted decision-making through using the information of systematical real-time operating status, be able to making a timely response dynamically according to the changes of the characteristics of simulation system, re-achieve balance and improve the system performance, fault-tolerant and load-balance ability according to the adjustment of the dynamic fluctuations of the loading. Taking the air-to-ground warfare simulation system as an example, simulation results verify that the method is effective and useful, and it could contribute to enhance using resource quotient and construct the large-scale military simulation applications.     

使用极限状态大圆筒土压力计算方法

通过对试验数据的分析 ,发现筒倾斜过程中 ,筒内土体的主动土压力及被动土压力的发育程度与筒内径的大小有密切关系。当筒内径足够大时 ,作用在筒内前、后壁上土压力特征与平面挡土墙基本相同。同时根据沉入式大圆筒倾斜过程中 ,作用在筒外壁上土压力沿筒轴分布有一个拐点的特征 ,提出筒倾斜过程绕泥面以下、筒底以上的筒壁某一点转动 ,转动点的具体位置同筒前土的特性有关。根据转动点的位置可以确定筒壁的位移方向及土压力的分布规律 ,为建立作用在筒壁上土压力的数学模型提供了依据。根据试验资料还提出了筒倾斜时土压力沿筒环向分布的规律及经验计算式     

T型管内油水分离特性的CFD-PBM数值模拟

目前关于T型管内油水分离特性的数值模拟大多采用Euler-Euler多相流模型,考虑管内油滴粒径分布及其对油水分离特性影响的研究工作尚未见报道。对T型管内的油水两相流动情况和分离特性进行了CFD-PBM数值模拟,并进行了室内实验以验证模拟结果的准确性。结果表明,T型管内油滴粒径随流体流动方向具有逐渐增大的趋势;增大来液中的油滴粒径分布可以有效提高油水分离效率,反之当来液中的油滴粒径较小时,油水两相在T型管内不易分离,相分配比始终与分流比几乎相同;分流比、Reynolds数等操作条件对油水分离效率的影响程度与油滴粒径密切相关,应慎重选取适当的操作条件以保证T型管的油水分离效率。     

不同绕流结构体对河道水流的影响

分别采用一维方形丁坝、二维梯形丁坝和三维堆积体概化模型,在同一水流条件下进行水槽试验,研究不同维度绕流结构体对河道水面线和三维时均流速的影响。试验结果表明:(1)在进占宽度比完全相同的情况下,梯形丁坝由于存在第一回流区,导致实际阻流面积最大,对上游阻流最强烈,方形丁坝次之,堆积体最小;(2)当阻流面积比(阻流流量比)相同时,方形丁坝在断面束窄河段的纵向流速加速能力比梯形丁坝强,水流横向偏转的幅度也更大,但梯形丁坝垂向流速比方形丁坝更大一些;(3)当沿水流方向长度相同时,堆积体由于最大截面面积较小,纵向、横向和垂向流速均小于丁坝。由此可见,常用于区分绕流结构体阻流特性的指标,如进占宽度比、阻流面积比和阻流流量比等,并不能全面表达结构体对流场的影响。     

Large-scale experimental study on scour around offshore wind monopiles under irregular waves

The Keulegan-Carpenter (KC) number is the main dimensionless parameter that affects the local scour of offshore wind power monopile foundations. This study conducted large-scale (1:13) physical model tests to study the local scour shape, equilibrium scour depth, and local scour volume of offshore wind power monopiles under the action of irregular waves with different KC numbers. Systematic experiments were carried out with the KC number ranging from 1.0 to 13.0. With a small KC number (KC < 6), and especially when the KC number was less than 4, the scour mainly occurred on both cross-flow sides of the monopile with a low scour depth. When the KC number exceeded 4, the shape of the scour hole changed from a fan to an ellipse, and the maximum scour depth increased significantly with KC. With a large KC number (KC > 6), the proposed method better predicted the equilibrium scour depth when the wave broke. In addition, according to the results of three-dimensional terrain scanning, the relationship between the local equilibrium scour volume of a single offshore wind power monopile and the KC number was derived. This provided a rational method for estimation of the riprap redundancy for monopile protection against scour.     

船闸运行状态与通过能力仿真分析

为定量分析和预报船闸的运行状态并指导其交通调度,基于Arena离散事件仿真平台,以湘江长沙枢纽双线船闸为例,通过已有研究成果建立船闸交通仿真模型,经实际资料验证该模型的可靠性,并分析了船闸在不同交通调度方案下的运行状态参数及最大通过能力。仿真分析结果表明,只有提高每个闸次的闸室利用率,才能有效增加船闸的通过能力;每个闸次的船舶艘数越多,一次过闸时间就长,平均延误就长。运行实践中可根据船闸状态和过闸交通需求,合理进行交通调度,在保障过闸安全的前提下协调船闸通过能力与船舶延误之间的关系。借助仿真输出的运行状态参数,有助于充分掌握船闸系统的交通规律,分析不同设计水平下的船闸最大通过能力,或是视不同交通负荷预选调度方案,综合提高过闸能力与服务质量。