Shape Optimization of High Speed Trains using Adjoint-Based Computational Fluid Dynamics

2012 ◽  
Vol 1 (2) ◽  
pp. 67-88 ◽  
Author(s):  
D. Jakubek ◽  
S. Herzog ◽  
C. Wagner
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Shape Optimization ◽  
High Speed ◽  
High Speed Trains

scholarly journals Aerodynamic analysis of uphill drafting in cycling

2021 ◽  
Vol 24 (1) ◽  
Author(s):  
T. van Druenen ◽  
B. Blocken
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Scientific Literature ◽  
Sensitivity Analyses ◽  
Air Resistance ◽  
Wind Tunnel Measurements ◽  
Aerodynamic Effect ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

AbstractSome teams aiming for victory in a mountain stage in cycling take control in the uphill sections of the stage. While drafting, the team imposes a high speed at the front of the peloton defending their team leader from opponent’s attacks. Drafting is a well-known strategy on flat or descending sections and has been studied before in this context. However, there are no systematic and extensive studies in the scientific literature on the aerodynamic effect of uphill drafting. Some studies even suggested that for gradients above 7.2% the speeds drop to 17 km/h and the air resistance can be neglected. In this paper, uphill drafting is analyzed and quantified by means of drag reductions and power reductions obtained by computational fluid dynamics simulations validated with wind tunnel measurements. It is shown that even for gradients above 7.2%, drafting can yield substantial benefits. Drafting allows cyclists to save over 7% of power on a slope of 7.5% at a speed of 6 m/s. At a speed of 8 m/s, this reduction can exceed 16%. Sensitivity analyses indicate that significant power savings can be achieved, also with varying bicycle, cyclist, road and environmental characteristics.

Slam load estimation for high-speed catamarans in irregular head seas by full-scale computational fluid dynamics

2021 ◽  
Vol 234 ◽  
pp. 109160
Author(s):  
Islam Almallah ◽  
Jason Ali-Lavroff ◽  
Damien S. Holloway ◽  
Michael R. Davis
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Full Scale ◽  
Load Estimation

Sailing Yacht Rig Improvements Through Viscous Computational Fluid Dynamics

2005 ◽  
Author(s):  
Vincent G. Chapin ◽  
Romaric Neyhousser ◽  
Stephane Jamme ◽  
Guillaume Dulliand ◽  
Patrick Chassaing
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
High Speed ◽  
Stokes Equations ◽  
Wind Tunnel Test ◽  
Physical Modelling ◽  
Optimized Design ◽  
Linear Interaction ◽  
Sailing Yacht

In this paper we propose a rational viscous Computational Fluid Dynamics (CFD) methodology applied to sailing yacht rig aerodynamic design and analysis. After an outlook of present challenges in high speed sailing, we emphasized the necessity of innovation and CFD to conceive, validate and optimize new aero-hydrodynamic concepts. Then, we present our CFD methodology through CAD, mesh generation, numerical and physical modelling choices, and their validation on typical rig configurations through wind-tunnel test comparisons. The methodology defined, we illustrate the relevance and wide potential of advanced numerical tools to investigate sailing yacht rig design questions like the relation between sail camber, propulsive force and aerodynamic finesse, and like the mast-mainsail non linear interaction. Through these examples, it is shown how sailing yacht rig improvements may be drawn by using viscous CFD based on Reynolds Averaged Navier-Stokes equations (RANS). Then the extensive use of viscous CFD, rather than wind-tunnel tests on scale models, for the evaluation or ranking of improved designs with increased time savings. Viscous CFD methodology is used on a preliminary study of the complex and largely unknown Yves Parlier Hydraplaneur double rig. We show how it is possible to increase our understanding of his flow physics with strong sail interactions, and we hope this methodology will open new roads toward optimized design. Throughout the paper, the necessary comparison between CFD and wind-tunnel test will be presented to focus on limitations and drawbacks of viscous CFD tools, and to address future improvements.

Transient Computational Fluid Dynamics/Discrete Element Method Simulation of Gas–Solid Flow in a Spouted Bed and Its Validation by High-Speed Imaging Experiment

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Ling Zhou ◽  
Lingjie Zhang ◽  
Weidong Shi ◽  
Ramesh Agarwal ◽  
Wei Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Discrete Element Method ◽  
Fluidized Bed ◽  
High Speed ◽  
Discrete Element ◽  
Bubble Shape ◽  
High Speed Imaging ◽  
Bed Height ◽  
Simulation Results

A coupled computational fluid dynamics (CFD)/discrete element method (DEM) is used to simulate the gas–solid two-phase flow in a laboratory-scale spouted fluidized bed. Transient experimental results in the spouted fluidized bed are obtained in a special test rig using the high-speed imaging technique. The computational domain of the quasi-three-dimensional (3D) spouted fluidized bed is simulated using the commercial CFD flow solver ANSYS-fluent. Hydrodynamic flow field is computed by solving the incompressible continuity and Navier–Stokes equations, while the motion of the solid particles is modeled by the Newtonian equations of motion. Thus, an Eulerian–Lagrangian approach is used to couple the hydrodynamics with the particle dynamics. The bed height, bubble shape, and static pressure are compared between the simulation and the experiment. At the initial stage of fluidization, the simulation results are in a very good agreement with the experimental results; the bed height and the bubble shape are almost identical. However, the bubble diameter and the height of the bed are slightly smaller than in the experimental measurements near the stage of bubble breakup. The simulation results with their experimental validation demonstrate that the CFD/DEM coupled method can be successfully used to simulate the transient gas–solid flow behavior in a fluidized bed which is not possible to simulate accurately using the granular approach of purely Euler simulation. This work should help in gaining deeper insight into the spouted fluidized bed behavior to determine best practices for further modeling and design of the industrial scale fluidized beds.

Adjoint-based shape optimization of high-speed trains

2014 ◽  
pp. 699-704 ◽  
Author(s):  
D Jakubek ◽  
S Herzog ◽  
C Wagner
Keyword(s):  
Shape Optimization ◽  
High Speed ◽  
High Speed Trains

Resistance Predictions for Asymmetrical Configurations of High-Speed Catamaran Hull Forms

2015 ◽  
Author(s):  
Srikanth Asapana ◽  
Prasanta K. Sahoo ◽  
Vaibhav Aribenchi
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Comparative Analysis ◽  
High Speed ◽  
Public Domain ◽  
Literature Survey ◽  
Historical Background ◽  
Resistance Analysis ◽  
Separation Ratio ◽  
Hull Forms

This paper attempts to undertake a comparative analysis of resistance characteristics between newly developed asymmetrical catamaran hull forms which were derived from existing conventional NPL series of round bilge catamaran hull forms by Molland, Wellicome and Couser (1994). A set of asymmetrical catamaran hull forms with waterline length of 1.6 m with a separation ratio (s/L) of 0.4 were generated by using standard modelling software. The resistance analysis had been carried out by using STAR CCM+, a computational fluid dynamics package for Froude numbers of 0.25, 0.30, 0.60, 0.80 and 1.0. Literature survey indicates that there is scant historical background in public domain to perform resistance analysis on asymmetrical catamaran hull forms. As this is not feasible due to lack of data in areas that were considered crucial, separate resistance analysis is carried out for each hull configuration. Finally, the compared resistance results will attempt to conclude whether asymmetrical catamaran hull forms are more efficient than the conventional catamaran hull forms.

Sign in / Sign up

Export Citation Format

Share Document