Ski-Jumping Aerodynamics: Model-Experiments and CFD-Simulations

2008 ◽  
pp. 183-216 ◽  
Author(s):  
Walter Meile ◽  
Wolfram Müller ◽  
Ewald Reisenberger
Keyword(s):  
Cfd Simulations ◽  
Model Experiments ◽  
Ski Jumping

Comparison of Experimental Towing Test and CFD Analysis of a Bare Hull Model on the Surface

2021 ◽  
Vol 163 (A3) ◽  
Author(s):  
Thu Han Tun ◽  
Ye Thet Htun ◽  
Aung Khaing Min
Keyword(s):  
Model Test ◽  
Surface Resistance ◽  
Surface Condition ◽  
Wave Formation ◽  
Complex Nature ◽  
Cfd Analysis ◽  
Cfd Simulations ◽  
Hull Form ◽  
Model Experiments ◽  
Key Aspects

In designing submarines, hull form selection, resistance, and powering are key aspects. The bare hull form of a submarine can be considered according to five parameters. Surface resistance is important should it be necessary to operate at relatively high Froude Numbers. Due to the complex nature of the flow around the hull, model experiments are still the most reliable approach to determining surface resistance. CFD simulations enable surface condition analysis using FINEMarine. The towing mechanism must be taken into account and so this was designed to fix the pitch motion and measure the hydrodynamic forces. This paper outlines the towing method, comparing the model test and the CFD results, as well as providing a comparison of wave formation from the towing test and the CFD results. The results show that resistance increased significantly above a model speed of 1.4 m/s. Furthermore, above this speed, as the resistance of the model rose, the downforce gradually decreased.

Aerodynamics of ski jumping: experiments and CFD simulations

2006 ◽  
Vol 41 (6) ◽  
pp. 949-964 ◽  
Author(s):  
W. Meile ◽  
E. Reisenberger ◽  
M. Mayer ◽  
B. Schmölzer ◽  
W. Müller ◽  
...  
Keyword(s):  
Cfd Simulations ◽  
Ski Jumping

CFD Simulation of Truss Spar Vortex-Induced Motion

2006 ◽  
Author(s):  
Sampath Atluri ◽  
John Halkyard ◽  
Senu Sirnivas
Keyword(s):  
Cfd Simulation ◽  
Turbulence Modeling ◽  
General Purpose ◽  
Scale Model ◽  
Cfd Simulations ◽  
Model Experiments ◽  
Helical Strakes ◽  
Induced Motion ◽  
Truss Spar ◽  
Hydrodynamic Effects

Helical strakes are used to suppress the Vortex-Induced Motion of Truss Spars. Model experiments have demonstrated the efficiency of strakes in the Truss Spar design but also indicate that the VIM response is sensitive to the details of strake design and placement of appurtenances around the Spar hull. It is desirable to study these hydrodynamic effects using CFD. The following paper is a continuation of some of the earlier CFD simulations on this subject (see, J. Halkyard, et al., “Benchmarking of Truss Spar Vortex-Induced Motions Derived from CFD with Experiments”, Proceedings of OMAE’05). This paper in particular deals with the effect of holes in the strakes and appurtenances and their placement. All the simulations were done at model scale (1:40 scale model of an actual Truss Spar design) to compare the motions with experimental results. Mesh sensitivity and turbulence modeling issues are also discussed. Calculations were done using general purpose CFD code Acusolve™.

Optimum Runner Design for Die Casting Using CFD Simulations and Verification With Water-Model Experiments

2014 ◽  
Author(s):  
Ken’ichi Kanazawa ◽  
Ken’ichi Yano ◽  
Jun’ichi Ogura ◽  
Yasunori Nemoto
Keyword(s):  
Molten Metal ◽  
Die Casting ◽  
Air Entrainment ◽  
Optimization Method ◽  
Water Model ◽  
Cfd Simulations ◽  
Mathematical Functions ◽  
Model Experiments ◽  
Runner Design ◽  
Pressure Die Casting

This study aimed to optimize the design of a runner for high-pressure die casting (HPDC) using computational fluid dynamics (CFD) simulations, and to verify the effectiveness of the runner with water-model experiments. A runner is a part of the flow path through which molten metal enters a product part. As a design problem, we sought to optimize the shape of the runner to minimize air entrainment in the runner and align the flow of molten metal after it passed through the runner. The problem was solved using our proposed nonparametric shape optimization method. The method is based on a genetic algorithm (GA), and directly treats a geometric shape that is comprised of several curves as an individual of a GA in the form of a set of mathematical functions. In addition, the crossover, which is one of the genetic operations, is defined as a weighted summation of two parent curves. Thus, the optimization method can generate optimized shapes with a lot of flexibility. The effectiveness of the optimized shape of the runner was demonstrated with both CFD simulations and water-model experiments using a visualization device for HPDC.

Designing and optimizing a stirring system for a cold model of a lithium electrolysis cell based on CFD simulations and optical experiments

RSC Advances ◽  
2015 ◽  
Vol 5 (103) ◽  
pp. 84503-84516 ◽  
Author(s):  
Ze Sun ◽  
Haiou Ni ◽  
Hang Chen ◽  
Suzhen Li ◽  
Guimin Lu ◽  
...  
Keyword(s):  
Electrolysis Cell ◽  
Lithium Metal ◽  
Cold Model ◽  
Cfd Simulations ◽  
Model Experiments ◽  
Electrolysis Cells

A new stirring system to separate lithium metal and chloride gas in lithium electrolysis cells has been designed and applied in cold model experiments.

Cognitive Components of Ingroup Projection

2014 ◽  
Vol 45 (1) ◽  
pp. 15-30 ◽  
Author(s):  
Maya Machunsky ◽  
Thorsten Meiser
Keyword(s):  
Mental Representation ◽  
Cognitive Representation ◽  
Social Categories ◽  
Projection Model ◽  
Minimal Group ◽  
Model Experiments ◽  
Superordinate Category ◽  
Cognitive Components ◽  
Per Se

This research investigated whether relative ingroup prototypicality (i.e., the tendency to perceive one’s own ingroup as more prototypical of a superordinate category than the outgroup) can result from a prototype-based versus exemplar-based mental representation of social categories, rather than from ingroup membership per se as previously suggested by the ingroup projection model. Experiments 1 and 2 showed that a prototype-based group was perceived as more prototypical of a superordinate category than an exemplar-based group supporting the hypothesis that an intergroup context is not necessary for biased prototypicality judgments. Experiment 3 introduced an intergroup context in a minimal-group-like paradigm. The findings demonstrated that both the kind of cognitive representation and motivational processes contribute to biased prototypicality judgments in intergroup settings.

Influence of Rim Run-Out on the Nonuniformity of Tire-Wheel Assemblies

1994 ◽  
Vol 22 (2) ◽  
pp. 99-120 ◽  
Author(s):  
T. B. Rhyne ◽  
R. Gall ◽  
L. Y. Chang
Keyword(s):  
Finite Element ◽  
Radial Force ◽  
Membrane Model ◽  
Model Experiments ◽  
Force Variation ◽  
One To One ◽  
The One

Abstract An analytical membrane model is used to study how wheel imperfections are converted into radial force variation of the tire-wheel assembly. This model indicates that the radial run-out of the rim generates run-out of the tire-wheel assembly at slightly less than the one to one ratio that was expected. Lateral run-out of the rim is found to generate radial run-out of the tire-wheel assembly at a ratio that is dependent on the tire design and the wheel width. Finite element studies of a production tire validate and quantify the results of the membrane model. Experiments using a specially constructed precision wheel demonstrate the behavior predicted by the models. Finally, a population of production tires and wheels show that the lateral run-out of the rims contribute a significant portion to the assembly radial force variation. These findings might be used to improve match-mounting results by taking lateral rim run-out into account.

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