scholarly journals Aerodynamics of Cycling Skinsuits Focused on the Surface Shape of the Arms

2021 ◽  
Vol 11 (5) ◽  
pp. 2200
Author(s):  
Sungchan Hong ◽  
Takeshi Asai
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Experiment ◽  
The Body ◽  
Surface Shape ◽  
Air Resistance ◽  
Computational Fluid Dynamics Cfd ◽  
Race Conditions ◽  
Cfd Method ◽  
Fabric Surface ◽  
Full Body

In cycling, air resistance corresponds to 90% of the resistance on the bicycle and cyclist and 70% of this is applied to the body of the cyclist. Despite research on postures that could reduce air resistance, few studies have been conducted on full-body cycling suits. As the aerodynamics of the surface shape of clothing fabric are still unclear, the airflow around cyclists and air resistance were examined using a computational fluid dynamics (CFD) method and wind tunnel experiment. Specifically, in this study, we focused on how different surface shapes of cycling suit fabrics affect air resistance. CFD results indicate that air resistance during a race was high at the head, arms and legs of the cyclist. In the wind tunnel experiment, a cylinder model resembling the arms was used to compare the aerodynamic forces of various fabrics and the results showed that air resistance changed according to the fabric surface shape. Moreover, by changing the fabric shape of the arms of the cycling suits, reduction of air resistance by up to 8% is achievable. These results suggest that offering the most appropriate suit type to each cyclist, considering race conditions, can contribute to further improvement in their performance.

scholarly journals Estimation of car air resistance by CFD method

2014 ◽  
Vol 36 (3) ◽  
pp. 235-244 ◽  
Author(s):  
Phan Anh Tuan ◽  
Vu Duy Quang
Keyword(s):  
Fluid Dynamics ◽  
Surface Area ◽  
Rolling Resistance ◽  
The Body ◽  
Ansys Fluent ◽  
Car Body ◽  
Air Resistance ◽  
Implicit Solver ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

Total car resistance is including rolling resistance and air resistance. Rolling resistance comes from car tires when it rolls over the roads with car weight. Air resistance comes from the body when it moves in the air with car body surface area. The air resistance of a car depends upon its shape. The bigger the surface area of a car body, the more air molecules the car will hit and so the larger the air resistance. This paper will mention to estimation of car air resistance by computational fluid dynamics (CFD) method. A 3D car body has used for simulation in ANSYS FLUENT CFD software. The k-\(\varepsilon\) turbulence model and segregated implicit solver was used to perform computation in this study.

Development of a Functional Speed Skating Uniform through Aerodynamic Analysis on Knit Textiles and Uniforms

2016 ◽  
Vol 11 (4) ◽  
pp. 155892501601100
Author(s):  
Youngjin Moon ◽  
Jooho Song ◽  
Kybeom Kwon ◽  
Ogyeong Kwon ◽  
Mikyung Kim ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Experiment ◽  
Second Phase ◽  
Body Parts ◽  
Wind Tunnel Experiments ◽  
Drag Coefficients ◽  
Pressure Drag ◽  
Speed Skating ◽  
Air Resistance ◽  
Individual Human

This study was carried out to improve speed skating uniforms through the development of materials to minimize air resistance and proper placement of the developed materials. Gliding of individual human body parts is studied via 3D simulation using Computational Fluid Dynamics. This study also conducted wind tunnel experiments by applying the developed uniform to a human-sized mannequin, based on cylinder wind tunnel experiment results on the empirically designed and developed knit textiles. As a result of the cylinder wind tunnel experiment for drag test on knit textiles, the existing product's drag coefficient was found to be 1.0, and the first-phase and second-phase developed textiles’ drag coefficients were 0.72 and 0.58, respectively. Therefore, air resistance was reduced, and the drag coefficients of the newly developed uniforms were lower than the existing uniform by 2.3~2.53%. From the results of this study, properly designed dimple-applied material reduces pressure drag by forming a turbulent boundary layer, compared to the material using smooth textile. A uniform consisting of the dimple-applied material is expected to improve athletic performance.

THE WIND TUNNEL DEVELOPMENT OF A PROPOSED EXTERNAL FORM FOR STEAM LOCOMOTIVES

1933 ◽  
Vol 8 (1) ◽  
pp. 37-61
Author(s):  
J. J. Green
Keyword(s):  
Wind Tunnel ◽  
Maximum Degree ◽  
Air Flow ◽  
Forward Direction ◽  
The Body ◽  
Air Resistance ◽  
Clean Air ◽  
Work Done ◽  
External Form ◽  
External Shape

The existing shape and arrangement of steam locomotives are such that smoke from the stack tends to sweep back along the boiler top and descend in front of the cab windows, seriously impairing forward vision. For the maximum degree of safety it is essential that the view from the cab, especially in a forward direction, should be unobstructed at all times. It is therefore desirable that some means be found for improving the manner in which the smoke is carried away from the stack. In addition to preventing the descent of smoke at the cab it is desirable that the external shape of the locomotive should be so modified as to result in a decreased air resistance, in view of the growing demand for economical running at increasingly higher speeds.The paper describes work done in the wind tunnel of the National Research Laboratories and discusses the steps whereby an improved external shape has been evolved for locomotives such that the smoke is lifted over the cab thus making possible an unimpaired vision ahead.The new design is the result of the application of elementary aerodynamics to the problem and aims at providing smoother air flow about the locomotive. Further, a layer of clean air is introduced between the smoke and the body of the locomotive and is responsible for maintaining the smoke above the cab. By removing the violent eddying flow about the locomotive the air resistance of the engine and tender has been reduced to the extent of some 35%.

scholarly journals Six-DOF CFD Simulations of Underwater Vehicle Operating Underwater Turning Maneuvers

2021 ◽  
Vol 9 (12) ◽  
pp. 1451
Author(s):  
Kunyu Han ◽  
Xide Cheng ◽  
Zuyuan Liu ◽  
Chenran Huang ◽  
Haichao Chang ◽  
...  
Keyword(s):  
Great Influence ◽  
Underwater Vehicle ◽  
The Body ◽  
Body Motion ◽  
Thrust Distribution ◽  
Turning Motion ◽  
Computational Fluid Dynamics Cfd ◽  
Six Dof ◽  
Cfd Method ◽  
Multi Body

Maneuverability, which is closely related to operational performance and safety, is one of the important hydrodynamic properties of an underwater vehicle (UV), and its accurate prediction is essential for preliminary design. The purpose of this study is to analyze the turning ability of a UV while rising or submerging; the computational fluid dynamics (CFD) method was used to numerically predict the six-DOF self-propelled maneuvers of submarine model BB2, including steady turning maneuvers and space spiral maneuvers. In this study, the overset mesh method was used to deal with multi-body motion, the body force method was used to describe the thrust distribution of the propeller at the model scale, and the numerical prediction also included the dynamic deflection of the control planes, where the command was issued by the autopilot. Then, this study used the published model test results of the tank to verify the effectiveness of the CFD prediction of steady turning maneuvers, and the prediction of space spiral maneuvers was carried out on this basis. The numerical results show that the turning motion has a great influence on the depth and pitch attitude of the submarine, and a “stern heavier” phenomenon occurs to a submarine after steering. The underwater turning of a submarine can not only reduce the speed to brake but also limit the dangerous depth. The conclusion is of certain reference significance for submarine emergency maneuvers.

scholarly journals Experiential ownership and body ownership are different phenomena

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Caleb Liang ◽  
Wen-Hsiang Lin ◽  
Tai-Yuan Chang ◽  
Chi-Hong Chen ◽  
Chen-Wei Wu ◽  
...  
Keyword(s):  
Conscious Experience ◽  
Distinct Type ◽  
Body Part ◽  
The Body ◽  
Body Ownership ◽  
Rubber Hand ◽  
Person Perspective ◽  
The One ◽  
First Time ◽  
Full Body

AbstractBody ownership concerns what it is like to feel a body part or a full body as mine, and has become a prominent area of study. We propose that there is a closely related type of bodily self-consciousness largely neglected by researchers—experiential ownership. It refers to the sense that I am the one who is having a conscious experience. Are body ownership and experiential ownership actually the same phenomenon or are they genuinely different? In our experiments, the participant watched a rubber hand or someone else’s body from the first-person perspective and was touched either synchronously or asynchronously. The main findings: (1) The sense of body ownership was hindered in the asynchronous conditions of both the body-part and the full-body experiments. However, a strong sense of experiential ownership was observed in those conditions. (2) We found the opposite when the participants’ responses were measured after tactile stimulations had ceased for 5 s. In the synchronous conditions of another set of body-part and full-body experiments, only experiential ownership was blocked but not body ownership. These results demonstrate for the first time the double dissociation between body ownership and experiential ownership. Experiential ownership is indeed a distinct type of bodily self-consciousness.

An anti-crystallization design of selective catalytic reduction nozzle holder

2021 ◽  
pp. 095440702097084
Author(s):  
Dewen Liu ◽  
Kai Lu ◽  
Shusen Liu ◽  
Yan Wu ◽  
Shuzhan Bai
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Injection System ◽  
Test Results ◽  
Verification Methods ◽  
Crystallization Risk ◽  
Protective Cover ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Good Agreement

From the aspect of reducing the risk of crystallization on nozzle surface, a new design of nozzle protective cover was to solve the problem in selective catalytic reduction (SCR) urea injection system. The simulation calculation and experimental verification methods were used to compare different schemes. The results show that reducing the height of nozzle holder can reduce the vortex currents near nozzle surface and effectively reduce the risk of crystallization on the nozzle surface. It is proposed to install a protective cover in the nozzle holder under the scheme of reducing the height of nozzle holder, which can further eliminate the vortex. Simulation and test results demonstrate good agreement under the rated running condition. The scheme of adding a protective cover in the nozzle holder shows the least crystallization risk by computational fluid dynamics (CFD) method. The crystallization cycle test shows that, after the height of nozzle holder is reduced, the risk of crystallization on the nozzle surface is reduced correspondingly. The addition of a protective cover in the nozzle holder solves the problem of crystallization on the nozzle surface, which provides a new method for anti-crystallization design.

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