Evolution laws of distributed vortex-induced pressures and energy of a flat-closed-box girder via numerical simulation

2020 ◽  
Vol 23 (13) ◽  
pp. 2776-2788
Author(s):  
Xingyu Chen ◽  
Yongle Li ◽  
Xinyu Xu ◽  
Haojun Tang ◽  
Bin Wang
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Rapid Development ◽  
Wind Tunnel Test ◽  
Simulation Method ◽  
Lower Surface ◽  
Box Girder ◽  
Vortex Induced Vibration ◽  
Aerodynamic Damping ◽  
Evolution Laws

This article investigates the vertical vortex-induced vibration of a flat-closed-box girder using numerical simulation method. The accuracy of simulation results is verified at first by comparing the displacement responses and vortex-induced force of vertical vortex-induced vibration with those obtained in a previous wind tunnel test of large-scale sectional model. The precision of extracting the vortex-induced pressures from the surface pressures and decomposing the vortex-induced pressures via the mathematical model is validated later. Subsequently, the vortex-induced pressures and energy distribution, and the evolution laws of vortex-induced pressures and energy are discussed. The results show that the linear aerodynamic negative damping and nonlinear aerodynamic positive damping are key factors of the rapid development of vortex-induced vibration and the self-limiting phenomenon separately. The positive aerodynamic damping is mainly provided by the lower surface and the middle of the upper surface, and the negative aerodynamic damping is primarily provided by the middle and downstream of the upper surface.

Numerical Simulation upon Explosion and Collapse of Viaduct

2014 ◽  
Vol 638-640 ◽  
pp. 1085-1091
Author(s):  
Shan Ji ◽  
Guang Hui Zhang ◽  
Wei Ping Xie
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Measurement Data ◽  
Soil Surface ◽  
Simulation Method ◽  
Numerical Results ◽  
Explosion Process ◽  
Vibration Responses

A rigorous scheme must be formulated in advance before a viaduct is to be exploded, in this case, numerical simulation can provide effective guarantee to the formulation of the scheme. Focusing on the explosion engineering of a large-scale city viaduct, the process of its explosion and collapse were simulated by the LS-DYNA software. The vibration responses of soil surface caused by the explosion and collapse were analyzed, and also the numerical results were compared with the measurement data. The numerical results agreed well with the measurement data, which showed that the simulation method proposed in the paper could simulate the explosion process well and the results could be also an guidline for the similar projections in future.

scholarly journals Study on Fluorine Pollution in a Slag Yard

2019 ◽  
Vol 9 (5) ◽  
pp. 847
Author(s):  
Lide Wei ◽  
Changfu Wei ◽  
Sugang Sui
Keyword(s):  
Numerical Simulation ◽  
Experimental Investigation ◽  
Numerical Simulations ◽  
Solute Transport ◽  
Large Scale ◽  
Three Dimensional ◽  
Simulation Method ◽  
Laboratory Studies ◽  
Survey Results ◽  
Simulation Results

This paper suggests a large-scale three-dimensional numerical simulation method to investigate the fluorine pollution near a slag yard. The large-scale three-dimensional numerical simulation method included an experimental investigation, laboratory studies of solute transport during absorption of water by soil, and large-scale three-dimensional numerical simulations of solute transport. The experimental results showed that the concentrations of fluorine from smelting slag and construction waste soil were well over the discharge limit of 0.1 kg/m3 recommended by Chinese guidelines. The key parameters of the materials used for large-scale three-dimensional numerical simulations were determined based on an experimental investigation, laboratory studies, and soil saturation of survey results and back analyses. A large-scale three-dimensional numerical simulation of solute transport was performed, and its results were compared to the experiment results. The simulation results showed that the clay near the slag had a high saturation of approximately 0.9, consistent with the survey results. Comparison of the results showed that the results of the numerical simulation of solute transport and the test results were nearly identical, and that the numerical simulation results could be used as the basis for groundwater environmental evaluation.

scholarly journals Numerical Simulation of Soil Displacement and Settlement in Deep Foundation Pit Excavations Near Water

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Zhongjing Hu ◽  
Qingbiao Wang ◽  
Shuo Yang ◽  
Zhenyue Shi ◽  
Bo Liu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Yellow River ◽  
Soft Soil ◽  
Ground Surface ◽  
Horizontal Displacement ◽  
Simulation Method ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit

Advancing urbanization in China requires large-scale high-rise construction and underground transportation projects. Consequently, there is an increasing number of deep foundation pits adjacent to water bodies, and accidents occur frequently. This study uses a numerical simulation method to study the stability of the deep foundation pit near water based on the Biot three-dimensional seepage-stress coupling model, with the open-cut section on the south bank of the Jinan Yellow River Tunnel Project as the engineering field test. This indicates the following: (1) the maximum horizontal displacement of the diaphragm wall occurred in the fifth excavation stage, and a horizontal brace effectively controlled the inward horizontal displacement of the foundation pit; (2) considering the effect of seepage in the soft soil foundation, the maximum vertical displacement of the ground surface at each excavation stage occurred adjacent to the underground continuous wall. As the depth of the foundation pit increased, the vertical surface settlement decreases gradually in the direction away from the excavation face; (3) considering the seepage conditions, within each interval of excavation of the foundation pit, the horizontal displacement of the continuous underground wall and ground settlement declined; and (4) the numerical simulation and field monitoring data were in good agreement. Under the conditions of accurate model simplification and parameter selection, numerical simulations can adequately forecast conditions of the actual project.

The Aerodynamic Analysis for Iced Four Bundled Transmission Lines with Typical Crescent

2014 ◽  
Vol 8 (1) ◽  
pp. 84-89 ◽  
Author(s):  
Liu Yuejun ◽  
Tang Ai P. ◽  
Liu Ke T. ◽  
Tu Jie W.
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Transmission Lines ◽  
Angle Of Attack ◽  
Wind Tunnel Test ◽  
Simulation Method ◽  
Single Wire ◽  
Wind Tunnel Tests ◽  
Absolute Value ◽  
Aerodynamic Test

Despite the fact that the wind tunnel tests have been carried out on iced transmission lines subjected to wind load, it is not practical to do wind tunnel tests due to its high cost. This paper describes a detailed numerical simulation method that can be used to instead of wind tunnel tests. Based on the galloping mechanism of iced transmission lines, the aerodynamic test was simulated with the typical crescent super-large thickness iced four bundled conductors. One of the results highlighted in this study is that the wind angle of attack had significant influence on the aerodynamics of iced conductors. The Den-Hartog and O.Nigol coefficient were calculated to determine galloping of iced transmission lines, comparing with the reference of wind tunnel test in the Zhejiang university, the range of the wind angle of attack to the bundled conductor which can lead to gallop is larger than single wire, but the absolute value of amplitude is less than the single conductor, split conductor is more likely to gallop than single conductor.

Vortex-Induced Vibration Optimization of a Wide Streamline Box Girder by Wind Tunnel Test

2018 ◽  
Vol 22 (12) ◽  
pp. 5143-5153 ◽  
Author(s):  
Ming Li ◽  
Yanguo Sun ◽  
Hongmiao Jing ◽  
Mingshui Li
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Box Girder ◽  
Vortex Induced Vibration

Research on Vortex-Induced Vibration Behavior of Steel Arch Bridge Hanger

2011 ◽  
Vol 137 ◽  
pp. 429-434 ◽  
Author(s):  
Ling Bai ◽  
Ke Liu
Keyword(s):  
Numerical Simulation ◽  
Wind Speed ◽  
Wind Tunnel ◽  
Vibration Amplitude ◽  
Wind Tunnel Test ◽  
Simulation Technique ◽  
Vortex Induced Vibration ◽  
Arch Bridge ◽  
Vibration Behavior ◽  
Numerical Simulation Technique

A fluid-structure interaction numerical simulation technique based on CFD has been developed to study the vortex-induced vibration behavior of steel arch bridge hanger. Above all, wind acting on bridge hanger is simulated by using Flunet and then vortex-induced dynamic motion of hanger is solved by method in the User Defined Function (UDF). Finally hanger’s transient vibration in wind is achieved by dynamic mesh method provided by Fluent. Using this technique, the vortex-induced vibration behavior of hanger of the Nanjing Dashengguan Yangtze River Bridge is analyzed, including vibration amplitude, vibration-started wind speed and vortex shedding frequency. The study also considers influences of different section type (rectangle, chamfered rectangle and H) of hanger. The following conclusions are obtained. Firstly hanger of different section has different vibration behavior. Secondly vibration-started wind speed of different section hanger differs with each other. Thirdly relation between vibration amplitude and incoming wind speed varies obviously. At the same time, numerical results are compared with those of one wind tunnel test and the out coming is satisfied. Relation between vibration amplitude and wind speed in both numerical simulation and wind tunnel test is similar because vibration-started wind speed in numerical result has only 10% discrepancy with that in wind tunnel test while vibration amplitude’s discrepancy is only 15%. Consequently, analysis results show the reliability of this numerical simulation technique.

Meshfree Method in Geophysical Electromagnetic Prospecting: The 2D Magnetotelluric Example

2017 ◽  
Vol 15 (02) ◽  
pp. 1750084 ◽  
Author(s):  
Yanju Ji ◽  
Tingzhe Huang ◽  
Wanyu Huang ◽  
Liangliang Rong
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
High Efficiency ◽  
Interpolation Method ◽  
Rapid Development ◽  
Linear Equations ◽  
Meshfree Method ◽  
Physical Parameters ◽  
Traditional Methods ◽  
Calculation Results

As an important supplement and development of traditional methods, the meshfree method has received a great deal of attention in the field of engineering calculation, and has been successfully used to solve many problems which traditional methods have difficulty in solving. However, the application of meshfree method is relatively less in the area of geophysics. In this paper, we apply the meshfree method to the numerical simulation of geophysical electromagnetic prospecting, taking the 2D magnetotelluric as an example and deduce the corresponding meshfree radial point interpolation method (RPIM) equivalent linear equations in detail. The high-efficiency and accurate solutions of large-scale sparse linear equations are solved by the quasi-minimal residual method based on Krylov subspace. The optimal values of the shape parameters are given by numerical experiments. The correctness of the meshfree method is verified by a layered model. The root mean square error of the calculation results is no more than 0.35%, its accuracy is superior to the finite element method. We also compare the meshfree solution with FEM solution by calculating an inclined vein body model, and the calculation results are in good agreement. A continuously changing fault model and undulating terrain model which traditional methods have difficulty in simulating are respectively calculated, the sectional profiles of the apparent resistivity accurately reflect the trend of the anomalies. The meshfree method does not require the complicated mesh generation, and the physical parameters are loaded at a series of points, thus it is especially suitable for the calculation of the complex geological models. With the rapid development of computational science, the meshfree techniques will certainly become a new robust numerical simulation method in geophysical electromagnetic prospecting.

scholarly journals Numerical simulation of turbulent convection over wavy terrain

1992 ◽  
Vol 237 ◽  
pp. 261-299 ◽  
Author(s):  
Kilian Krettenauer ◽  
Ulrich Schumann
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Fluid Layer ◽  
Domain Size ◽  
Lower Surface ◽  
Constant Heat Flux ◽  
Computational Domain ◽  
Turbulent Structures ◽  
Convective Boundary ◽  
Scale Motion

Thermal convection of a Boussinesq fluid in a layer confined between two infinite horizontal walls is investigated by direct numerical simulation (DNS) and by large-eddy simulation (LES) for zero horizontal mean motion. The lower-surface height varies sinusoidally in one horizontal direction while remaining constant in the other. Several cases are considered with amplitude δ up to 0.15H and wavelength λ of H to 8H (inclination up to 43°), where H is the mean fluid-layer height. Constant heat flux is prescribed at the lower surface of the initially at rest and isothermal fluid layer. In the LES, the surface is treated as rough surface (z0 = 10−4H) using the Monin-Oboukhov relationships. At the flat top an adiabatic frictionless boundary condition is applied which approximates a strong capping inversion of an atmospheric convective boundary layer. In both horizontal directions, the model domain extends over the same length (either 4H or 8H) with periodic lateral boundary conditions.We compare DNS of moderate turbulence (Reynolds number based on H and on the convective velocity is 100, Prandtl number is 0.7) with LES of the fully developed turbulent state in terms of turbulence statistics and Characteristic large-scale-motion structures. The LES results for a flat surface generally agree well with the measurements of Adrian et al. (1986). The gross features of the flow statistics, such as profiles of turbulence variances and fluxes, are found to be not very sensitive to the variations of wavelength, amplitude, domain size and resolution and even the model type (DNS or LES), whereas details of the flow structure are changed considerably. The LES shows more turbulent structures and larger horizontal scales than the DNS. To a weak degree, the orography enforces rolls with axes both perpendicular and parallel to the wave crests and with horizontal wavelengths of about 2H to 4H. The orography has the largest effect for λ = 4H in the LES and for λ = 2H in the DNS. The results change little when the size of the computational domain is doubled in both horizontal directions. Most of the motion energy is contained in the large-scale structures and these structures are persistent in time over periods of several convective time units. The motion structure persists considerably longer over wavy terrain than over flat surfaces.

scholarly journals Research on Sand-dust Separation Technology Based on Gas-solid Two-phase Numerical Simulation

2020 ◽  
Vol 145 ◽  
pp. 02068
Author(s):  
Lei Zhang ◽  
Junwei Wang ◽  
Guohua Li
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Separation Efficiency ◽  
Simulation Method ◽  
Test System ◽  
Two Phase ◽  
Separation Technology ◽  
Electromechanical Products ◽  
Environment Simulation ◽  
Sand Dust

The separation technology in the large-scale sand-dust environment ground simulation test system applicable to the environmental adaptability and reliability verification of aerospace electromechanical products is studied. The gas-solid two-phase numerical simulation method is adopted, and the possible cyclone separation, inertial separation methods are used to study the separation efficiency and regularity technology, which provides a basis for the separation design and test of the sand-dust environment simulation of large electromechanical products.

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