This work used the computational fluid dynamics method combined with full-scale train tests to analyze the train aerodynamic performance on special slope topography. Results show that with the increment in the slope g...This work used the computational fluid dynamics method combined with full-scale train tests to analyze the train aerodynamic performance on special slope topography. Results show that with the increment in the slope gradient, the aerodynamic forces and moment increase sharply. Compared with the flat ground condition, the lateral force, lift force, and overturning moment of the train on the first line increase by 153.2%, 53.4% and 124.7%, respectively, under the slope gradient of 20°. However, with the increment of the windward side's depth, the windbreak effect is improved obviously. When the depth is equal to 10 m, compared with the 0 m, the lateral force, lift force and overturning moment of the train on the first line decrease by 70.9%, 77.0% and 70.6%,respectively. Through analyzing the influence of slope parameters on the aerodynamic performance of the train, the relationships among them are established. All these will provide a basic reference for enhancing train aerodynamic performances under different slope conditions and achieve reasonable train speeds for the operation safety in different wind environments.展开更多
The instability of continental slopes damages marine engineering equipment,such as submarine pipelines,resulting in the generation of tsunamis,which endangers the safety of nearshore personnel.Therefore,research on th...The instability of continental slopes damages marine engineering equipment,such as submarine pipelines,resulting in the generation of tsunamis,which endangers the safety of nearshore personnel.Therefore,research on the instability of continental slopes where submarine landslides usually occur is crucial to the risk evaluation of deepwater drilling.Previous studies were mainly based on simplified 2D and 3D models,which extend the 2D model applied on submarine slopes with complex topography.In this study,a numerical model with bathymetric data from the Qiongdongnan Basin was established.Furthermore,3D slope stability analysis and static and dynamic analyses were conducted.The static analysis found two discussions where slopes are most likely to occur.Through the analysis of different seismic forces,the dynamic result showed that an instability area is added to the two positions where the static analysis is unstable.Topography scatters and transmits seismic waves and controls the accumulation and diffusion of seismic energy.3D calculations and analysis revealed that the direction of slope instability is closely related to terrain inclination,slope,terrain effect,and terrain curvature.Data showed that instability situations could not be derived from a single direction or profile data.Such situations are an important factor in slope stability analysis and are critical to the prediction and evaluation of marine geological disasters.展开更多
The propagation and evolution of long nonlinear internal solitary waves over slope-shelf topography is theoretically and numerically studied in a two-layer fluid system of finite depth.The variable Korteweg–de Vries(...The propagation and evolution of long nonlinear internal solitary waves over slope-shelf topography is theoretically and numerically studied in a two-layer fluid system of finite depth.The variable Korteweg–de Vries(vKdV)and variable extended Korteweg–de Vries(veKdV)equations are derived for the weak and moderate nonlinear waves,respectively.The numerical method is developed from finite difference/volume(FD/FV)scheme to solve the nonlinear equations.The transformation of solitary waves is observed when they propagate past the slope.The elevation of rear face of the front wave grows with the increase of the slope inclination.The results also show that the transformed waves can be described by the steady solution of the corresponding theoretical model(vKdV,veKdV)by considering the depth condition beyond the shelf.展开更多
基金Projects(U1334205,U1134203)supported by the National Natural Science Foundation of ChinaProject(132014)supported by the Fok Ying Tong Education Foundation,ChinaProjects(2014T001-A,2015T002-A,2015J007-N)supported by China Railways Corporation
文摘This work used the computational fluid dynamics method combined with full-scale train tests to analyze the train aerodynamic performance on special slope topography. Results show that with the increment in the slope gradient, the aerodynamic forces and moment increase sharply. Compared with the flat ground condition, the lateral force, lift force, and overturning moment of the train on the first line increase by 153.2%, 53.4% and 124.7%, respectively, under the slope gradient of 20°. However, with the increment of the windward side's depth, the windbreak effect is improved obviously. When the depth is equal to 10 m, compared with the 0 m, the lateral force, lift force and overturning moment of the train on the first line decrease by 70.9%, 77.0% and 70.6%,respectively. Through analyzing the influence of slope parameters on the aerodynamic performance of the train, the relationships among them are established. All these will provide a basic reference for enhancing train aerodynamic performances under different slope conditions and achieve reasonable train speeds for the operation safety in different wind environments.
基金This study was supported by the National Key Research and Development Program of China(No.2019YFC0312301)the Nation Natural Science Foundation of China(No.U1701245).
文摘The instability of continental slopes damages marine engineering equipment,such as submarine pipelines,resulting in the generation of tsunamis,which endangers the safety of nearshore personnel.Therefore,research on the instability of continental slopes where submarine landslides usually occur is crucial to the risk evaluation of deepwater drilling.Previous studies were mainly based on simplified 2D and 3D models,which extend the 2D model applied on submarine slopes with complex topography.In this study,a numerical model with bathymetric data from the Qiongdongnan Basin was established.Furthermore,3D slope stability analysis and static and dynamic analyses were conducted.The static analysis found two discussions where slopes are most likely to occur.Through the analysis of different seismic forces,the dynamic result showed that an instability area is added to the two positions where the static analysis is unstable.Topography scatters and transmits seismic waves and controls the accumulation and diffusion of seismic energy.3D calculations and analysis revealed that the direction of slope instability is closely related to terrain inclination,slope,terrain effect,and terrain curvature.Data showed that instability situations could not be derived from a single direction or profile data.Such situations are an important factor in slope stability analysis and are critical to the prediction and evaluation of marine geological disasters.
基金This work is supported by the China Postdoctoral Science Foundation(Grant no.2017M621455)National Natural Science Foundation of China(Grant no.11072153).
文摘The propagation and evolution of long nonlinear internal solitary waves over slope-shelf topography is theoretically and numerically studied in a two-layer fluid system of finite depth.The variable Korteweg–de Vries(vKdV)and variable extended Korteweg–de Vries(veKdV)equations are derived for the weak and moderate nonlinear waves,respectively.The numerical method is developed from finite difference/volume(FD/FV)scheme to solve the nonlinear equations.The transformation of solitary waves is observed when they propagate past the slope.The elevation of rear face of the front wave grows with the increase of the slope inclination.The results also show that the transformed waves can be described by the steady solution of the corresponding theoretical model(vKdV,veKdV)by considering the depth condition beyond the shelf.
