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1.
It is imperative to develop a risk assessment system for quickly predicting storm surge disaster due to the vulnerability of Tianjin Binhai New Area. The flood routing model with user-defined breaches was firstly established based on the seed spread algorithm in order to achieve a rapid forecasting of storm surge flood information. Furthermore, fuzzy mathematics was utilized to identify the storm disaster grade, and the hazard mapping was conducted to visually obtain the hazard spatial and temporal distribution. Finally, the flood routing visualization method was proposed based on numerical simulation of storm surge to achieve the reappearance scene of dynamic evolution process. The developed system can play a vital role in the management and decision-making of sea dyke mitigation engineering in Tianjin Binhai New Area. 相似文献
2.
The occurrence of storm surge disaster is often accompanied with floodplain, overflow, dike breach and other complex phenomena, while current studies on storm surge flooding are more concentrated on the 1D/2D numerical simulation of single disaster scenario(floodplain, overflow or dike breach), ignoring the composite effects of various phenomena. Therefore, considering the uncertainty in the disaster process of storm surge, scenario analysis was firstly proposed to identify the composite disaster scenario including multiple phenomena by analyzing key driving forces, building scenario matrix and deducing situation logic. Secondly, by combining the advantages of k-ω and k-ε models in the wall treatment, a shear stress transmission k-ω model coupled with VOF was proposed to simulate the 3D flood routing for storm surge disaster. Thirdly, risk degree was introduced to make the risk analysis of storm surge disaster. Finally, based on the scenario analysis, four scenarios with different storm surge intensity(100-year and 200-year frequency) were identified in Tianjin Binhai New Area. Then, 3D numerical simulation and risk map were made for the case. 相似文献
3.
运用局部有限元和有限差分相结合的方法,建立起适用于潮汐地区的一种简便的二维潮流水质数学模型.将该模型应用到哑铃湾的COD模拟,并在IBM微型机上成功地进行了模拟计算.结果表明本模型对潮流场中的水质模拟是有效的。 相似文献
4.
风暴潮极值状态下珠江河网白坭水道内的不稳定流动 总被引：1，自引：0，他引：1
利用1999年洪季和9316号台风风暴潮的实测资料,通过ECOMSED数学模型对珠江河网广州区域进行数值模拟计算.计算结果显示,在99年洪季时,河网内白坭水道流动为通常的往复流动;但在风暴潮极值状态下,由于受极值流速及地形的影响,流动在白坭水道中弯曲扭摆,呈现出流动不稳定现象. 相似文献
5.
In this paper, to study the characteristics of the flow in a laminar regime, an immersed boundary-lattice Boltzmann flux solver (IB-LBFS) is applied to numerically simulate the unsteady viscous flows around two fixed and rotating circular cylinders in side-by-side arrangement. This method applies finite volume discretization to solve the macroscopic governing equations with the flow variables defined at cell centers. At the cell interface, numerical fluxes are physically evaluated by a local lattice Boltzmann solution. In addition, the no-slip boundary condition is accurately imposed by using the implicit boundary condition-enforced immersed boundary method. Due to the simplicity and high efficiency of IB-LBFS on non-uniform grids, it is suitable for simulating fluid flows with complex geometries and moving boundaries. Firstly, numerical simulations of laminar flow past two side-by-side cylinder are performed with different gap spacings at Reynolds numbers of 100 and 200. The simulation results show that a small gap spacing induces a biased flow and forms an irregular big wake behind two cylinders at a low Reynolds number. As the gap spacing increases, an in-phase or anti-phase flow is observed. Then, the effects of the main important parameters on flow characteristics are analyzed for flow past two side-by-side rotating cylinders, including the rotational speed, Reynolds number, and gap spacing. As the rotational speed is increased, the numerical results illustrate that unsteady wakes are suppressed and the flow becomes steady. As the gap spacing is increased, two separate vortex streets behind each cylinder are formed with a definite phase relationship and single shedding frequency. 相似文献
6.
In order to research the feasibility of artificial neural network (ANN) in the research of eutrophication of the Bohai Bay in China, an ANN model simulating chlorophyll a, b and c concentrations, concerning temperature, dissolved oxygen, salinity, pH value, chemical oxygen demand (COD), PO43-, NO2-and NO3-factors in the Bohai Bay was presented and validated. After experiencing and training by Matlab, the model′s validation mean square error (MSE) performance is 0.009 985 02. R-squared between estimated and observed concentrations of chlorophyll a, b and c are 0.965 7, 0.998 7 and 0.970 7 respectively, indicating that the estimated value agrees with the observed value well, and the model can be used in the prediction of eutrophication of the Bohai Sea. In order to study the influence of model input factors on chlorophyll concentration (i.e. model outputs), hypothetical scenarios were introduced to show model output responses to variations in input factors. The limitation of temperature, salinity and phosphate that induce red tide in the Bohai Bay was also presented. 相似文献
7.
The hydraulic oscillation of surge tank was analyzed through numerical simulation.A rectangular integral scheme was established in order to improve the numerical model.According to the boundary control equation of surge tank, the rectangular integral scheme omits the second-order infinitesimal and simplifies the solving process.An example was provided to illustrate the rectangular integral scheme, which is compared with the traditional trapezoid integral scheme.Appropriate numerical solutions were gained th... 相似文献
8.
SELEZNEV V. E PRYALOV S. N 《浙江大学学报(A卷英文版)》2007,8(11):1775-1788
This paper presents a method of forecasting stable operation of gas compressor unit (GCU) centrifugal supercharger (CFS) installed on a piping of compressor shops servicing gas pipelines. The stability of superchargers operation is assessed in relation to the phenomenon of surge. Solution of this problem amounts to the development and numerical analysis of a set of ordinary differential equations. The set describes transmission of gas through a compressor shop as a fluid dynamics model with lumped parameters. The proposed method is oriented to wide application by specialists working in the gas industry. The practical application of this method can use all-purpose programming and mathematical software available to specialists of gas companies. 相似文献
9.
为天津地铁改建、扩建所需 ,采用数学模拟方法对原有站台通风系统的气流组织效果进行评价 ,在此基础上提出通风系统的改建方案 ,并对新方案的速度场、温度场进行优化 .借助实际流场的测试数据判断紊流模型的适用性 ,并通过现场测试获得了所需边界条件值 .模拟结果与实测数据相符 ,证明了双方程紊流模型用于模拟站台的复杂流场是可行的 .模拟时将列车进站过程的瞬时流简化为稳定流 ,并对此假设前提下模拟结果的有效性给予认证 . 相似文献
10.
Numerical simulation of a gas pipeline network using computational fluid dynamics simulators 总被引：1，自引：0，他引：1
SELEZNEV Vadim 《浙江大学学报(A卷英文版)》2007,8(5):755-765
This article describes numerical simulation of gas pipeline network operation using high-accuracy computational fluid dynamics (CFD) simulators of the modes of gas mixture transmission through long, multi-line pipeline systems (CFD-simulator). The approach used in CFD-simulators for modeling gas mixture transmission through long, branched, multi-section pipelines is based on tailoring the full system of fluid dynamics equations to conditions of unsteady, non-isothermal processes of the gas mixture flow. Identification, in a CFD-simulator, of safe parameters for gas transmission through compressor stations amounts to finding the interior points of admissible sets described by systems of nonlinear algebraic equalities and inequalities. Such systems of equalities and inequalities comprise a formal statement of technological, design, operational and other constraints to which operation of the network equipment is subject. To illustrate the practicability of the method of numerical simulation of a gas transmission network, we compare computation results and gas flow parameters measured on-site at the gas transmission enter-prise. 相似文献
11.
Numerical Analysis of Soil Plug Inside Suction Foundations During Suction Penetration by Discrete Element Method 总被引：2，自引：1，他引：2
The phenomenon of the soil plug usually rising inside the suction foundations during suction penetration was quantitatively described and predicted. The formation process of the soil plug was simulated and calculated by DEM （discrete element method） model. The seepage flow, the self-weight of soil, the friction on the chamber wall as well as the suction inside the chamber are considered as the main external forces in the process. The results are compared with a set of laboratory model tests performed by using three soil types （sand, silty clay and clay） in the Bohai Sea area. The heights of soil plug from numerical estimations are lower than those from model test results, mainly because the suction pressure and friction resistance are applied in an ideal way under the numerical simulation. 相似文献
12.
文章以福建教育学院为例,介绍了利用VRML虚拟现实技术进行三维虚拟校园建模仿真的过程,重点阐述了三维场景建模、场景优化以及场景交互等在构建虚拟校园过程中涉及的关键技术,并最终实现了交互式虚拟校园漫游系统。 相似文献
13.
This paper establishes a 3D numerical model for 15# hydropower house of the Three Gorges Project (TGP) and performs a nonlinear static and dynamic damage analysis. In this numerical model, a coupling model of finite and infinite elements for simulating infinite foundation of hydropower station is adopted. A plastic-damage model based on continuum damage mechanics, which includes the softening and damage behavior under tension is considered for the concrete material. The dynamic equilibrium equations of motion are solved by using the HilberHughes-Taylor (HHT) time integration method. Firstly, the static damage response analysis of the hydropower station is conducted due to high tensile stress resulting from large water head and diameter of an inlet pipe. Then, on the basis of static simulation, the dynamic damage analysis of hydropower house subjected to earthquake motion is simulated. Numerical results show that under large water head and diameter of an inlet pipe of the project, the damages are mainly located near the top of the spiral case from the inlet section to the 0° section; under combined loadings of static loads and earthquake, the damages of the concrete surrounding the spiral case increase insignificantly; however, some damages occur on the side walls of the main powerhouse. 相似文献
14.
Comprehensive risk analysis of storm surge flood based on WebGIS 总被引：1，自引：1，他引：0
The comprehensive risk analysis of storm surge flood is vital to the safety management of sea embank- ment, the scientific assessment of storm surge disaster and the improvement of emergent treatment in storm surge haz- ard. Based on the research of disaster-causing, disaster-pregnant and disaster-bearing factors, the influencing factors of storm surge risk are concluded to be flood natural risk, embankment position, embankment width and height. The membership degree of the factors of storm surge risk is firstly determined by storm surge flood evolution based on WebGIS, and the comprehensive risk membership and risk grade of each influencing factor are obtained. Then the effects of a single factor on comprehensive risk and sensitivity analysis are discussed, and the storm surge flood risk map is obtained. Finally, the storm surge of Tianjin Binhai New Area is taken as a case. The results show that the in- fluencing degree of the factors on the comprehensive risk membership is in decreasing order of flood natural risk, em- bankment position, embankment width and height. The flood risk map of the case is drawn, which is useful to decrease losses caused by storm surge disaster. 相似文献
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16.
In this paper, a stabilized finite element technique, actualized by streamline upwind Petrov-Galerkin (SUPG) stabilized method
and three-step finite element method (FEM), for large eddy simulation (LES) is developed to predict the wind flow with high
Reynolds numbers. Weak form of LES motion equation is combined with the SUPG stabilized term for the spatial finite element
discretization. An explicit three-step scheme is implemented for the temporal discretization. For the numerical example of
2D wind flow over a square rib at Re=4.2×105, the Smagorinsky’s subgrid-scale (SSGS) model, the DSGS model, and the DSGS model with Cabot near-wall model are applied,
and their results are analyzed and compared with experimental results. Furthermore, numerical examples of 3D wind flow around
a surface-mounted cube with different Reynolds numbers are performed using DSGS model with Cabot near-wall model based on
the present stabilized method to study the wind field and compared with experimental and numerical results. Finally, vortex
structures for wind flow around a surface-mounted cube are studied by present numerical method. Stable and satisfactory results
are obtained, which are consistent with most of the measurements even under coarse mesh. 相似文献
17.
为了在大范围数学模型中合理有效地模拟码头桩基等小尺度建筑物附近的潮流场,采用非结构网格建立了渤海二维有限元潮流数学模型.在面积达85 700 km2的模型范围中将码头桩基概化为面积约20-30 m2的不透水单元,用于直接模拟桩基附近的复杂潮流场.在此基础上,对渤海曹妃甸海域10万吨级LNG(液化天然气)码头布置的走向进行了优化.结果表明:数学模型模拟的潮位和流速等水动力特征与实测结果一致,LNG码头布置的优化结果合理可信.表明建立的能够直接模拟小尺度建筑物的渤海二维有限元数学模型可应用于码头工程布置及优化的潮流场模拟研究. 相似文献
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19.
A numerical simulation of the interaction between laminar flow with low Reynolds number and a highly flexible elastic sheet is presented. The mathematical model for the simulation includes a three-dimensional finitevolume based fluid solver for incompressible viscous flow and a combined finite-discrete element method for the three-dimensional deformation of solid. An immersed boundary method is used to couple the simulation of fluid and solid. It is implemented through a set of immersed boundary points scattered on the solid surface. These points provide a deformable solid wall boundary for the fluid by adding body force to Navier-Stokes equations. The force from the fluid is also obtained for each point and then applied on the boundary nodes of the solid. The vortex-induced vibration of the highly flexible elastic sheet is simulated with the established mathematical model. The simulated results for both swing pattern and oscillation frequency of the elastic sheet in low Reynolds number flow agree well with experimental data. 相似文献
20.
针对潜水一维非稳定流方程,先分别采用分离变量法和有限差分法进行求解,然后对比解析解结果,讨论显式差分法和隐式差分法的求解精度,最后将研究成果应用在某基坑降水水位预测中。研究结果表明:采用分离变量法可有效求解一类边界下潜水一维非稳定流方程;在相同密度网格剖分下,显式差分法较隐式差分法的求解精度要高,但显式差分法对网格剖分要求较高,实际应用时可根据计算精度以及计算效率等要求综合选用求解方法。 相似文献