物理-数值复合模型在模拟多股水舌进入复杂河道的流场中的应用

结合溪洛渡工程下游河道消能防冲物理模型试验，将物理模型试验与数值模型相结合，建立复合模型，并应用该模型对多股水舌进入复杂天然河道后的流场结构进行模拟，计算结果表明多股水舌进入下游复杂河道的流场结构受河道复杂几何形状影响较大，河道复杂的几何形状对水舌两侧或上下游侧回流区和两岸侧螺旋流的对称性影响较大，螺旋流输运长度较常规水垫塘情况的短；根据计算得到的流场，对下游河道冲刷特性进行了预测与分析。计算中三维的自由面模拟直接采用物理模型实测结果进行。复合模型模拟的结果和实验结果吻合良好，表明在实际的工程问题研究中，该方法能够有效地解决单纯依靠物理模型不易解决的复杂地形条件和复杂入流边界条件的三维复杂问题。     

多股多层水平有压淹没射流消能特性研究

对多股多层水平淹没射流有压体型消能特性和水力特性进行了消能分析和试验研究．实测的消力池底板压力分布特性、流态稳定性、流速衰减规律表明，采用有压射流将高速下泄水流导入下游水体中，利用三元强剪切及紊动消能，可大大降低临底流速，减小消力池底板上的动水冲击，增加淹没射流消能的稳定性，减小了雾化对周围环境的影响，是一种消能率高、低雾化、适应性较好、安全的新型消能方式、但是，对于中孔进口位置较低的水利枢纽工程存在深水闸门受力过大及开启条件限制较多等不足。     

3-D hybrid LES-RANS model for simulation of open-channel T-diversion flows

The study of flow diversions in open channels plays an important practical role in the design and management of open-channel networks for irrigation or drainage.To accurately predict the mean flow and turbulence characteristics of open-channel dividing flows,a hybrid LES-RANS model,which combines the large eddy simulation (LES) model with the Reynolds-averaged Navier-Stokes (RANS) model,is proposed in the present study.The unsteady RANS model was used to simulate the upstream and downstream regions of a main channel,as well as the downstream region of a branch channel.The LES model was used to simulate the channel diversion region,where turbulent flow characteristics ate complicated.Isotropic velocity fluctuations were added at the inflow interface of the LES region to trigger the generation of resolved turbulence.A method based on the virtual body force is proposed to impose Reynolds-averaged velocity fields near the outlet of the LES region in order to take downstream flow effects computed by the RANS model into account and dissipate the excessive turbulent fluctuations.This hybrid approach saves computational effort and makes it easier to properly specify inlet and outlet boundary conditions.Comparison between computational results and experimental data indicates that this relatively new modeling approach can accurately predict open-channel T-diversion flows.     

横流中射流及其温度标量输运大涡模拟

将动力拟序涡黏性亚格子应力模型拓展到温度标量亚格子模型中,数值模拟了横流条件下有、无温度标量场作用的射流,得到的横流条件下浮力射流的温度和速度分布与Anwar的试验值吻合一致。在此基础上,分析了有、无温度标量场作用下射流回流区域大小和射流轨迹线特性,对比分析了回流区域内涡心和分离点处湍动能和耗散率、拟涡能以及边界层处拟序结构等湍流特性。计算结果表明:温度场的作用使射流的回流区域增大,射流速度轨迹线高度增加,回流区域内湍流的湍动能增加,边界处拟序结构的周期性不如无温度场时明显。     

A 3D analytical model for vortex velocity field based on spiral streamline pattern

Vortices that develop over intakes are a hazardous hydraulic phenomenon. In this study, a 3D model was developed to study the flow field in air-core vortices. This model is based on the spiral pattern of streamlines and the analytical solution of the momentum and continuity equations for deriving the three components of velocity. The model provides equations for free surface profiles and 3D patterns of the streamlines. Moreover, a new relationship was suggested for calculating effective viscosity and its distribution across the vortex flow field. The performance of the proposed analytical model was compared with existing experimental data and the results of previous analytical models. The outcomes indicated that the proposed model could predict characteristics of the vortex flow with good accuracy.     

环形UV消毒器流场模拟及湍流模型的研究

为了预测紫外反应器的流场特性,利用CFD技术,分别采用标准k-ε模型、Realizablek-ε模型、低雷诺k-ε模型和雷诺应力模型(RSM)进行了水力特性的模拟.结果表明:在x=0,z=1 cm以及x=0,z=83 cm处,4种湍流模型对z向流速的模拟结果都较符合PIV实验数据,在x=0,z=15 cm处,Realizable k-ε模型的模拟结果偏差较大,在x=0,z=64cm处,标准k-ε模型的模拟偏差较其他3种模型大.综合比较,低雷诺k-ε模型和RSM模型的模拟结果较为理想.     

基于 BP 神经网络的大坝新多测点位移模型

大坝位移监测资料分析大多以单一测点得到的数据建立模型,这种单测点模型无法反映大坝作为一个整体各点位移之间的相互联系,也就不能真实地反映坝体的整体安全性态。为此,将多个同源测点联合考虑,通过测点之间的相关性对目标测点建模,再通过该模型推求未布置测点位置的大坝位移值,为推求大坝整体单向位移创造条件。经实例验证,这种新模型在对目标测点的位移预测和补全缺失数据两方面相对常规的单测点模型效果更佳,而且在对未知点的位移值进行预测方面也具有良好效果。     

尾闾河道及海域整体冲淤数学模型研究

针对黄河下游水少沙多和河口淤积延伸速度快的特点,本文建立了一套包括一维河道和二维海域、适用于多沙河口的整体泥沙冲淤数学模型。模型建立在高含沙的不平衡输沙理论上,采用动边界和动床阻力技术,模型可同时考虑径流、潮流及波浪等多种动力因素共同作用,可用于尾闾河道冲淤、河口泥沙输移扩散和河口演变计算。本文 应用二维模型计算了整个渤海的潮汐过程,得到几个主要分潮的同潮图,计算与实测值符合良好。用1983年汛后至1996年汛前艾山-口门河道地形资料、1996年6～10月和1996年10月～2000年10月的海区地形资料对一、二维连接模型进行了验证。计算结果给出的黄河下游河道的淤积延伸过程、河道水位、河道及海区冲淤量和流路河长延伸等均与实测值基本一致,证实了模型的可靠性。     

多元线性回归与GM（1，1）模型耦合预测城市用水量

合理预测城市用水量对于城市的发展有着极其重要的意义。本文首先应用多元回归的方法，采取向前选择变量法进行优选，得到相对最优的回归预测模型。然后利用灰色GM（1，1）模型，预测出规划年每个变量的值，代入多元回归模型，这样充分利用了两种模型的优点，预测精度高，结果更为合理可靠。     

Scour depths at sites selected for spawning by brown trout (Salmo trutta) along a longitudinal gradient of a North American mountain river

In the Intermountain West, USA, fry of fall‐spawning brown trout (Salmo trutta) are susceptible to scour‐related mortality because they are still in the gravel during spring snowmelt run‐off events. The goal of our research was to understand patterns of gravel scour on the Logan River, Utah, in relation to brown trout spawning and whether mobility of spawning gravels could explain the absence of brown trout from higher elevations. We collected data to characterize local entrainment potential at spawning gravels longitudinally on the Logan River during 2009 and 2010 spring flood events. We used scour chains to measure scour depth at spawning locations, and we also examined the position of redds in channel cross sections in relation to the centre line. The flood magnitude in both years approximated the 2‐year flood magnitude, but the flood in 2009 was much longer in duration. Scour at 27% of scour chain locations exceeded the estimated median upper limit of developing fry in 2009, whereas scour at 0% of locations exceeded this depth in 2010. Brown trout spawned in locations with similar entrainment potential at both mid and high elevations, which contributed to a lack of trend in scour depth with elevation. In addition, the majority of areas chosen for spawning were channel margins. The relationship between local entrainment potential at spawning gravels and scour depth was similar for the mid‐elevation canyon zone with medium brown trout density and the high‐elevation noncanyon zone with low brown trout density. In a low‐elevation backwater zone containing high densities of brown trout, scour was high despite low levels of entrainment potential. Overall, findings suggest that spawning gravel scour is not limiting brown trout abundance at high elevations in this system given shallow scour depths overall and a general lack of increase in scour depth with increasing elevation/distance upstream.     

利用单纯形-粒子群算法识别二维河流水质参数

将单纯形-粒子群混合算法应用于分析二维河流横向扩散情况下的水团示踪试验数据,估计河流的横向扩散系数、断面平均流速和污水排放位置。数值试验结果表明:(1)加速因子c_1,c_2和参数初值取值范围综合影响粒子的搜索能力,当加速因子c_1=c_2=1.72时,有利于保持粒子的搜索能力;(2)在同样的条件下,混合算法的时间性能指标值小于单一的粒子群优化算法;(3)参数初值的取值范围对混合算法收敛性几乎没有影响;(4)混合算法可以有效地应用于河流水质数学模型参数识别问题。混合算法能改善粒子群算法在迭代后期出现的收敛速度慢、早熟的不足,是分析河流水质模型参数的一种有效方法。     

A linear hybrid model of MSE and BEM for floating structures in coastal zones

1. INTRODUCTION In coastal zones, wave propagation in water is considerably affected by the topography of the sea bottom, which may result in changes in the direction and shape of the waves and may cause redistribution of their energy in space, etc. Waves may also lose a certain amount of energy by wavebreaking or by other forms of dissipation. It can be easily seen that wave propagation in shallow waters is a very complicated process resulting from various mechanisms. The dominant mechan…     

河型变化段河工动床模型设计方法研究

以模型相似原理为基础，结合黄河小浪底至花园口河段河道整治模型试验研究，对河型变化段河工动床模型设计方法进行了初步探索，提出了“分段设计、过渡处理”的设计方法．辩证地解决了同一模型具有不同河型河段的河工动床模型设计问题。     

混凝土裂缝开度混合预测模型

分析了传统统计预测模型的不足,研究了统计与混沌混合预测模型建模的一般原理,提出了一种混凝土坝裂缝开度的统计与混沌混合预测模型,利用紧支柱径向基函数对该模型进行了实现,结合实例对这种混合预测模型进行了检验,实例分析表明,该模型预测精度较高,具有一定实用性.     

基于水文学与水力学方法的雅砻江水情预报模型

以雅砻江官地水库至河口为对象,建立一个基于水文学与水力学方法相耦合的水情预报模型。其中,官地水库出流作为模型入流边界,官地水库至二滩水库河道汇流采用马斯京根河道演算法模拟;官地水库至二滩水库区间入流采用基于栅格的新安江模型模拟,以使模拟结果具有一定的预见期;二滩水库按水库调度规则计算水库出流;二滩水库至河口对完全圣维南方程组采用一维非恒定流隐式差分求解,模拟出沿河道任意断面水情过程,从而使具有预见期的水文预报成果沿河道方向得到了延伸,实现了对二滩水库至河口段水情的精准预报和过程控制。采用2007—2009年日系列资料对模型进行严格的率定与验证后发现,小得石站最高水位的绝对误差均小于0.3 m,桐子林站最大流量的相对误差均小于10%,日模拟的确定性系数均高于0.989,高精度的模拟结果证实了模型的合理性和有效性。     

Development and application of a eutrophication water quality model for river networks

The Preissmann implicit scheme was used to discretize the one-dimensional Saint-Venant equations, the river-junction-fiver method was applied to resolve the hydrodynamic and water quality model for river networks, and the key issues on the model were expatiated particularly in this article. This water quality module was designed to compute time dependent concentrations of a series of constituents, which are primarily governed by the processes of advection, dispersion and chemical reactions. Based on the theory of Water Quality Analysis Simulation Program （WASP） water quality model, emphasis was given to the simulation of the biogeochemical transformations that determine the fate of nutrients, in particular, the simulation of the aquatic cycles of nitrogen and phosphorus compounds. This model also includes procedures for the determination of growth and death of phytoplankton. This hydrodynamic and water quality model was applied to calculate two river networks. As illustrated by the numerical examples, the calculated water level and discharge agree with the measured data and the simulated trends and magnitudes of water quality constituents are generally in good agreement with field observations. It is concluded that the presented model is useful in the pollutant control and in the determination of pollutant-related problems for river networks.     

一维不恒定流河网数学模型研究与应用

河道中洪水数值模拟主要用求解描述洪水波运动的圣维南方程组,依数值计算解法不同而产生了不同的模型．在海河流域大清河北支及中下游河道洪水数值模拟的实际工作中,应用了一维河网模型进行洪水的模拟计算,并根据实际情况加入了蓄滞洪区调度、泄洪闸控制调度以及近年来北方河道入渗的特点等条件,计算效果良好．现对模型的理论基础和解法以及实际应用经验作一简述。     

湖泊-河网耦合水动力水质模型研究

根据太湖地区水系复杂、湖泊众多、河道水流方向复杂多变且受到人为干扰的特征,基于一维河网水质模型,二维湖泊水质模型,采用有限控制体积法获得离散的水动力学和水质模型控制方程,通过河网与湖泊连接断面上河流的流量、水位、水质与湖泊的流速、水位和水质耦合求解,解决了河网湖泊水质模型的耦合,并将闸站控制对河流湖泊水动力水质影响过程进行了时间空间的线性化处理,以边界条件方式将闸站控制带入模型代数方程中进行统一求解,建立了适合于太湖流域的湖泊河网耦合水动力水质模型.采用太湖典型流域河网区2007年实测水文水质资料对耦合模型进行率定和验证.结果表明,模型计算值与实测资料吻合较好.该模型适用于复杂湖泊-河网区的水动力和水质变化的模拟和研究.     

不确定条件下的多水源联合供水调度模型

本文针对城市供水调度系统中存在的不确定性与复杂性,运用区间两阶段随机规划的方法,建立了多水源联合供水调度的优化模型。该模型以供水调度系统成本最小为目标函数,引入概率分布及区间数表示不确定性,模拟了地表水源、地下水源、外来水源等多种水源联合供水过程,并对多种水源的调水目标进行优化。以区间形式给出优化结果,为决策者提供宽裕的决策空间。利用该方法,可充分考虑系统中不确定因素对系统成本的影响,更真实的反映多水源联合供水系统的实际情况。     

河谷局地气象场的WRF模式边界层方案敏感性分析

在河谷局地气象场对泄洪雾化的影响研究中,不同边界层方案的模拟效果并不明确,需要对边界层方案进行敏感性分析。使用WRF模式获取河谷地形的局地气象场,选择RMM5近地面层方案并搭配使用8种边界层方案进行对比分析。研究表明:风速受到河谷地形的影响,模拟效果不够理想,可耦合小尺度数值模式以提高其模拟效果;WRF能模拟河谷地形的狭管效应、风速增大以及风向逐渐偏向河谷方向,压强和温度的模拟效果较好。综合各气象要素的模拟结果,YSU和MYNN2边界层方案的模拟精度较高。该方法对泄洪雾化效应和水库环境水文气象效应研究具有参考价值。