scholarly journals Experimental and numerical study on the influence of wall roughness on the ventilation resistance coefficient in a tunnel under construction

2022 ◽  
Vol 119 ◽  
pp. 104198
Author(s):  
Zhiqiang Zhang ◽  
Yinjun Tan ◽  
Heng Zhang ◽  
Yu Zhao ◽  
Xingyu Zhu
Keyword(s):  
Numerical Study ◽  
Resistance Coefficient ◽  
Wall Roughness ◽  
Under Construction

Tunnel performance during the Puebla-Mexico 19 September 2017 earthquake

2020 ◽  
Vol 36 (2_suppl) ◽  
pp. 288-313
Author(s):  
Juan M Mayoral ◽  
Gilberto Mosqueda ◽  
Daniel De La Rosa ◽  
Mauricio Alcaraz
Keyword(s):  
Mexico City ◽  
Seismic Performance ◽  
Urban Areas ◽  
Numerical Study ◽  
Three Dimensional ◽  
Frequency Content ◽  
Seismic Performance Evaluation ◽  
Ground Deformations ◽  
Under Construction ◽  
Observed Damage

Seismic performance of tunnels during earthquakes in densely populated areas requires assessing complex interactions with existing infrastructure such as bridges, urban overpasses, and metro stations, including low- to medium-rise buildings. This article presents the numerical study of an instrumented tunnel, currently under construction on stiff soils, located in the western part of Mexico City, during the Puebla-Mexico 19 September 2017 earthquake. Three-dimensional finite difference models were developed using the software FLAC3D. Initially, the static response of the tunnel was evaluated accounting for the excavation technique. Then, the seismic performance evaluation of the tunnel was carried out, computing ground deformations and factors of safety, considering soil nonlinearities. Good agreement was observed between predicted and observed damage during post-event site observations. Once the soundness of the numerical model was established, a numerical study was undertaken to investigate the effect of frequency content in tunnel-induced ground motion incoherence for tunnels built in cemented stiff soils. A series of strong ground motions recorded during normal and subduction events were used in the simulations, considering a return period of 250 years, as recommended in the Mexico City building code. From the results, it was concluded that the tunnel presence leads to important frequency content modification in the tunnel surroundings which can affect low- to mid-rise stiff structures located nearby. This important finding must be taken into account when assessing the seismic risk in highly populated urban areas, such as Mexico City.

Numerical Study of Circular Tube inserted Arc Belt on Fluid Flow and Heat Transfer under Laminar Flow

2013 ◽  
Vol 561 ◽  
pp. 460-465
Author(s):  
Dong Hui Zhang ◽  
Jiao Gao
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Laminar Flow ◽  
Wall Temperature ◽  
Circular Tube ◽  
Numerical Study ◽  
Resistance Coefficient ◽  
Uniform Wall Temperature ◽  
Flow And Heat Transfer ◽  
Uniform Wall

The objective of this paper is to study the characteristic of a circular tube with a built-in arc belt on fluid flow and heat transfer in uniform wall temperature flows. Numerical simulations for hydrodynamically laminar flow was direct ran at Re between 600 and 1800. Preliminary results on velocity and temperature statistics for uniform wall temperature show that, arc belt can swirl the pipe fluid, so that the fluid at the center of the tube and the fluid of the boundary layer of the wall can mix fully, and plays the role of enhanced heat transfer, but also significantly increases the resistance of the fluid and makes the resistance coefficient of the enhanced tube greater than smooth tube. The combination property PEC is all above 1.5.

Numerical Investigation on Resistance Reducing Effect by Mass Injection through Porous Wall

2014 ◽  
Vol 670-671 ◽  
pp. 838-842
Author(s):  
Yong Zhao ◽  
Tian Lin Wang
Keyword(s):  
Numerical Investigation ◽  
Numerical Study ◽  
Porous Wall ◽  
Frictional Resistance ◽  
Resistance Coefficient ◽  
Good Prediction ◽  
Complex Flow ◽  
Mass Injection ◽  
Layer Flow ◽  
Frictional Resistance Coefficient

A numerical study of flow in two-dimensional turbulent boundary layer flow with mass injection through a porous wall is conducted by Reynolds averaged numerical simulation (RANS) in this paper. Numerical results with available experimental data show that Wilcox (2006) k-w turbulence model can give good prediction in this complex flow. The comparison between mass injection and no mass injection for the local frictional resistance coefficient are performed. Numerical investigation indicates that mass injection may reduce the resistance significantly, which is confirmed by comparison of velocity profiles qualitatively.

Numerical Study on the Resistance and Sinkage of Inland Vessels Passing Through Navigable Tunnel

2020 ◽  
Author(s):  
Xuehua Chen ◽  
Lizheng Wang ◽  
Shunhuai Chen ◽  
Aokui Xiong
Keyword(s):  
Numerical Study ◽  
Forward Motion ◽  
Free Condition ◽  
Limited Size ◽  
Calculation Results ◽  
Fixed Condition ◽  
Vessel Resistance ◽  
Under Construction ◽  
Vessel Motion ◽  
Water Depths

Abstract While passing through a navigable tunnel, a vessel usually undergoes a steady forward motion at low speed. Due to the limited size of the navigable tunnel, the restricted water conditions of small section-coefficient will have an adverse impact on vessel navigation safety. A bottom suction effect on vessels may occur for the risk of grounding and harming the maneuvering performance. Thus, it is particularly important to reveal the effect of the navigable tunnel scale on the vessel sinkage. In this paper, a numerical model of the representative 1000-ton vessel of the Wujiang channel under construction is established. Numerical simulations of the vessel are conducted based on RANS equations in deep water, both in fixed condition and free condition (i.e. the trim and sinkage are allowed). And the validity of the method is verified by comparing the calculation results with the experimental ones. Subsequently, for diverse water depths, water widths and vessel speeds, the parameters such as the vessel resistance and sinkage are predicted and compared. The calculation results are analyzed to obtain the trend of vessel motion at different tunnel scales. In addition, the effect of the tunnel scale on vessel navigation performance is also investigated.

Numerical Study of Wall Roughness Effect on Proppant Transport in Complex Fracture Geometry

2017 ◽  
Author(s):  
Xu Huang ◽  
Peng Yuan ◽  
Hao Zhang ◽  
Jiahang Han ◽  
Alberto Mezzatesta ◽  
...  
Keyword(s):  
Numerical Study ◽  
Wall Roughness ◽  
Roughness Effect ◽  
Fracture Geometry ◽  
Proppant Transport ◽  
Complex Fracture

Numerical Study of Large Diameter Butterfly Valve on Flow Characteristics

2011 ◽  
Vol 236-238 ◽  
pp. 1653-1657 ◽  
Author(s):  
Xiao Dong Wang ◽  
Jing Liang Dong ◽  
Tian Wang
Keyword(s):  
Pressure Drop ◽  
Flow Resistance ◽  
Numerical Study ◽  
Large Diameter ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Numerical Approach ◽  
Resistance Coefficient ◽  
Butterfly Valve ◽  
Dimensional Simulation

A numerical approach was used to investigate the flow characteristics around a butterfly valve with the diameter of 2108 mm by the commercial computational fluid dynamics (CFD) code FLUENT6.3. The simulation was carried out to predict flow field structure, flow resistance coefficient, hydrodynamics torque and so on, when the large diameter butterfly valve operated at various opening degrees. The three-dimensional simulation results shown that there are vortexes presented near valve back region as the opening degree smaller than 40 degree; the flow resistance coefficient reduces rapidly with the increasing of opening degree and the resistance coefficient is quite small as the angle larger than 50 degree; the hydrodynamic torque reduces with the increasing of opening degree and the hydrodynamic torque is smaller than 20% of maximum torque; the torque ratio and the pressure drop ratio are reduce with the increasing of opening degree, the pressure drop ratio reduces rapidly as the opening degree is smaller than 50 degree.

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