scholarly journals Three-Dimensional CFD Analysis of the Hand and Forearm in Swimming

2011 ◽  
Vol 27 (1) ◽  
pp. 74-80 ◽  
Author(s):  
Daniel A. Marinho ◽  
António J. Silva ◽  
Victor M. Reis ◽  
Tiago M. Barbosa ◽  
João P. Vilas-Boas ◽  
...  
Keyword(s):  
Drag Coefficient ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Three Dimensional ◽  
Force Production ◽  
Realistic Model ◽  
Hydrodynamic Characteristics ◽  
Force Coefficient ◽  
Commercial Code ◽  
Dimensional Domain

The purpose of this study was to analyze the hydrodynamic characteristics of a realistic model of an elite swimmer hand/forearm using three-dimensional computational fluid dynamics techniques. A three-dimensional domain was designed to simulate the fluid flow around a swimmer hand and forearm model in different orientations (0°, 45°, and 90° for the three axes Ox, Oy and Oz). The hand/forearm model was obtained through computerized tomography scans. Steady-state analyses were performed using the commercial code Fluent. The drag coefficient presented higher values than the lift coefficient for all model orientations. The drag coefficient of the hand/forearm model increased with the angle of attack, with the maximum value of the force coefficient corresponding to an angle of attack of 90°. The drag coefficient obtained the highest value at an orientation of the hand plane in which the model was directly perpendicular to the direction of the flow. An important contribution of the lift coefficient was observed at an angle of attack of 45°, which could have an important role in the overall propulsive force production of the hand and forearm in swimming phases, when the angle of attack is near 45°.

Experimental Study on Hydrodynamic Characteristics of Three-Stranded Polyethylene Rope

2014 ◽  
Vol 490-491 ◽  
pp. 421-429 ◽  
Author(s):  
Liu Yi Huang ◽  
Lin Zhang ◽  
Tian Wei Dong ◽  
Rong Wan ◽  
Fen Fang Zhao ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Lift Coefficient ◽  
Flow Speed ◽  
Attack Angle ◽  
Hydrodynamic Characteristics ◽  
Force Coefficient ◽  
Force Components ◽  
And Performance ◽  
Model Region

Three-stranded polyethylene ropes and twines are widely used as one of the main materials for fishery facilities. The shape and performance of the net fishing facilities in water are determined by the hydrodynamic properties of these ropes and twines. In the present work, experiment investigation was made in the flume tank in Tokyo University of Marine Science and Technology. Five kinds of three-stranded polyethylene rope with different sizes of diameter were tested. Drag and lift forces, together with sideways force acting on ropes under various trial conditions were measured by underwater load cells which were independently developed by the authors to record three axial force components. The drag, lift and sideways forces per unit rope length, under various attack angles at several flow velocities were obtained through data analysis. Then the drag coefficient, the lift coefficient and the sideways force coefficient were calculated within the range of Reynolds numberRd= 2.5×103~3.0×104. The following conclusions may be made from the experimental results: (1) At all the three testing attack angles i.e. 45o, 60o and 90o, the drag per unit rope length is proportional to the square of flow speed; (2) As the attack angle equal to 90o, the drag coefficient can be expressed in a power function of Reynolds number as given below: It can be inferred that the drag coefficient is approximately equal to 1.4 in the automatic model region, i.e. 1.2×104<Rd< 3.0×104. (3) As the attack angle equal to 45o or 60o, the lift force per unit rope length is proportional to the 2.5thpower of flow speed and the lift coefficient has a similar trend as the drag coefficient. But the lift coefficient makes smaller fluctuation compared to the drag coefficient when tending to a constant value in the automatic model region, i.e. 1.2×104<Rd<3.0×104.

Experimental Aerodynamic Characteristics of a Compound Wing in Ground Effect

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Saeed Jamei ◽  
Adi Maimun Abdul Malek ◽  
Shuhaimi Mansor ◽  
Nor Azwadi Che Sidik ◽  
Agoes Priyanto
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Center Of Pressure ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Ground Effect ◽  
Reynolds Numbers ◽  
Aerodynamic Characteristics ◽  
Ground Clearance

Wing configuration is a parameter that affects the performance of wing-in-ground effect (WIG) craft. In this study, the aerodynamic characteristics of a new compound wing were investigated during ground effect. The compound wing was divided into three parts with a rectangular wing in the middle and two reverse taper wings with anhedral angle at the sides. The sectional profile of the wing model is NACA6409. The experiments on the compound wing and the rectangular wing were carried to examine different ground clearances, angles of attack, and Reynolds numbers. The aerodynamic coefficients of the compound wing were compared with those of the rectangular wing, which had an acceptable increase in its lift coefficient at small ground clearances, and its drag coefficient decreased compared to rectangular wing at a wide range of ground clearances, angles of attack, and Reynolds numbers. Furthermore, the lift to drag ratio of the compound wing improved considerably at small ground clearances. However, this improvement decreased at higher ground clearance. The drag polar of the compound wing showed the increment of lift coefficient versus drag coefficient was higher especially at small ground clearances. The Reynolds number had a gradual effect on lift and drag coefficients and also lift to drag of both wings. Generally, the nose down pitching moment of the compound wing was found smaller, but it was greater at high angle of attack and Reynolds number for all ground clearance. The center of pressure was closer to the leading edge of the wing in contrast to the rectangular wing. However, the center of pressure of the compound wing was later to the leading edge at high ground clearance, angle of attack, and Reynolds number.

scholarly journals Effect of vortex generator on the flow field over a conventional delta wing in subsonic flow condition at higher angles of attack

2021 ◽  
Vol 49 (2) ◽  
pp. 395-400
Author(s):  
Manthan Patil ◽  
Rajesh Gawade ◽  
Shubham Potdar ◽  
Khushabu Nadaf ◽  
Sanoj Suresh ◽  
...  
Keyword(s):  
Flow Field ◽  
Flow Visualization ◽  
Drag Coefficient ◽  
Subsonic Flow ◽  
Delta Wing ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Vortex Generator ◽  
Oil Flow ◽  
Oil Flow Visualization

Flow over a conventional delta wing has been studied experimentally at a subsonic flow of 20 m/sec and the flow field developed at higher angle of attack varying from 10° to 20° has been captured. A vortex generator is mounted on the leeward surface of the delta wing and its effect on the flow field is studied. The set of wing tip vortices generated over the delta wing is captured by the oil flow visualization and the streamline over the delta wing surface captured with and without a vortex generator are compared. Based on the qualitative results, the effect of the vortex generator on the lift coefficient is anticipated. Further, force measurement is carried out to quantitatively analyze the effect of vortex generator on the lift and drag coefficient experienced by the delta wing and justify the anticipation made out of the qualitative oil flow visualization tests. In the present study, the effect of mounting of a vortex generator is found to be minimal on the lift coefficient experienced by the delta wing. However, a significant reduction in the drag coefficient with increase in angle of attack was observed by mounting a typical vortex generator.

scholarly journals Analysis on Flow Field Characteristics of Airfoil in Pitching Motion

2021 ◽  
Vol 2076 (1) ◽  
pp. 012069
Author(s):  
Rui Yin ◽  
Jing Huang ◽  
Zhi-Yuan He
Keyword(s):  
Flow Field ◽  
Drag Coefficient ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Decisive Role ◽  
Aerodynamic Characteristics ◽  
Pitching Motion ◽  
Maximum Value ◽  
Flow Field Characteristics ◽  
Lift And Drag

Abstract Based on CFD, the flow field characteristics of NACA4412 airfoil are analyzed under pitching motion, and its aerodynamic characteristics are interpreted. The results show that streamline changes on the upper surface of the airfoil play a decisive role in the aerodynamic characteristics. The interaction between the vortex leads to fluctuations in the lift and drag coefficients. Under a big angle of attack, the secondary trailing vortex on the upper surface of the airfoil adheres to the trailing edge of the airfoil, resulting in an increased drag coefficient. Under a small angle of attack, the secondary trailing vortex can break away from the airfoil. The lift coefficient reaches the maximum value of 2.961 before the airfoil is turned upside down, and the drag coefficient reaches the maximum value of 1.515 after the airfoil is turned upside down, but the corresponding angles of attack of the two are equal.

Three-Dimensional Wing Design Towards the Future Mars Airplane

2011 ◽  
Author(s):  
Ryoji Kojima ◽  
Donghi Lee ◽  
Tomoaki Tatsukawa ◽  
Taku Nonomura ◽  
Akira Oyama ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Drag Coefficient ◽  
Lift Coefficient ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Viscous Drag ◽  
Stream Velocity ◽  
Main Stream ◽  
Lower Reynolds Number

The effects of aspect ratio and Reynolds number on aerodynamic characteristics of three-dimensional rectangular wing at low Reynolds number of 103 to 105, are investigated with Reynolds-averaged Navier-Stokes solver with the Baldwin-Lomax model. Present results show that lift coefficient decreases drastically at lower aspect ratio than 4. Besides, the much larger viscous drag coefficient is obtained at the lower Reynolds number, especially lower than 104. In order to focus on designing practical wings, the particular cases under the condition of fixed wing-surface area and fixed main stream velocity are conducted. The results show that there is trade-off between the decrease in viscous drag coefficient with increasing Reynolds number and the increase in lift coefficient with increasing aspect ratio. At the lower Reynolds number condition, as the former effect is stronger than the latter one, maximum lift-to-drag ratio is obtained at lower aspect ratio.

scholarly journals Dynamic Stall Characteristics of the Bionic Airfoil with Different Waviness Ratios

2021 ◽  
Vol 11 (21) ◽  
pp. 9943
Author(s):  
Liming Wu ◽  
Xiaomin Liu
Keyword(s):  
Drag Coefficient ◽  
Lift Coefficient ◽  
Three Dimensional ◽  
Leading Edge ◽  
Dynamic Stall ◽  
Humpback Whales ◽  
Blade Vibration ◽  
Vibration Load ◽  
Unsteady Numerical Simulation ◽  
Bionic Airfoil

A dynamic stall will cause dramatic changes in the aerodynamic performance of the blade, resulting in a sharp increase in the blade vibration load. The bionic leading-edge airfoil with different waviness ratios, inspired by the humpback whales flipper, is adopted to solve this problem. In this study, based on the NACA0015 airfoil, the three-dimensional unsteady numerical simulation and sliding mesh technique are used to reveal the flow control mechanism on the dynamic stall of the bionic wavy leading edge. The effects of the waviness ratio on the dynamic stall characteristics of the airfoil are also investigated. The results show that the peak drag coefficient is dramatically reduced when a sinusoidal leading edge is applied to the airfoil. Although the peak lift coefficient is also reduced, the reduction is much smaller. When the waviness ratio R is 0.8, the peak drag coefficient of the airfoil is reduced by 17.14% and the peak lift coefficient of the airfoil is reduced by 9.20%. The dynamic hysteresis effect is improved gradually with an increasing waviness ratio. For the bionic airfoil with R = 1.0, the area of the hysteresis loop is the smallest.

scholarly journals STUDY OF MESH REFINEMENT ON THE AERODYNAMIC COEFFICIENTS FOR NACA2412 PROFILE WITH DIFFERENT ANGLE OF ATTACK AND k - w TURBULENCE MODEL

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Nícolas Lima Oliveira ◽  
Eric Vargas Loureiro ◽  
Patrícia Habib Hallak
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Lift Coefficient ◽  
Mesh Refinement ◽  
Angle Of Attack ◽  
Aerodynamic Coefficients ◽  
Computational Fluid Dynamics Cfd

This work presents the studies  obtained using OpenFOAM OpenSource Computational Fluid Dynamics (CFD) Software. Experiments were performed to predict lift coefficient and drag coefficient curves for the NACA2412 profile. Subsequently, the results obtained were compared with the results of the bibliography and discussed.

scholarly journals ANALISIS CFD KARAKTERISTIK AERODINAMIKA PADA SAYAP PESAWAT LSU-05 DENGAN PENAMBAHAN VORTEX GENERATOR (ANALYSIS OF CFD AERODYNAMIC CHARACTERISTICS AT THE WING OF AIRCRAFT LSU-05 WITH THE ADDITION OF VORTEX GENERATOR)

2017 ◽  
Vol 15 (1) ◽  
pp. 45
Author(s):  
Awalu Romadhon ◽  
Dana Herdiana
Keyword(s):  
Drag Coefficient ◽  
Cfd Simulation ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Vortex Generator ◽  
Aerodynamic Characteristics ◽  
Unmanned Aircraft ◽  
Vortex Generators ◽  
Aircraft Wing ◽  
Ansys Fluent

LSU-05 aircraft is one of the unmanned aerial vehicles (UAV), which is being developed by the Aeronautics Technology Center of LAPAN, whose mission is for research, observation, patrol, border surveillance, and investigation of natural disasters. This study aims to determine the effect of vortex generators on the aerodynamic characteristics of the LSU-05 Unmanned Aircraft wing. The method used is a numerical analysis with CFD simulation for predicting aerodynamic characteristics and flow phenomena that occur. The models used are the aircraft wing of the LSU-05 without vortex generator and with vortex generator designed with CATIA software. The simulation is using ANSYS Fluent software to determine changes in the aerodynamic characteristics of the wing after the addition of vortex generators such as the lift coefficient and drag coefficient. The results of the addition of vortex generator on LSU-05 wings are the increasing value of the maximum lift coefficient of the wing which becomes 1,34840 from 1,26450, it increases 0,0839 (6.63%) point, the increasing value of the drag coefficient on the angle of attack from -9⁰ to 11⁰, the decreasing value of the drag coefficient on the angle of attack 12⁰ up to 15⁰ and the increasing stall angle of wing from 11⁰ to 14⁰ or increased by 3⁰ (27,7%). AbstrakPesawat LSU-05 adalah salah satu pesawat tanpa awak (UAV) yang sedang dikembangkan oleh Pusat Teknologi Penerbangan LAPAN, yang mempunyai misi untuk kegiatan penelitian, observasi, patroli, pengawasan perbatasan wilayah, dan investigasi bencana alam. Penelitian ini bertujuan untuk mengetahui pengaruh penambahan vortex generator terhadap karakteristik aerodinamika dari sayap Pesawat Tanpa Awak LSU-05. Metode yang digunakan adalah analisis numerik dengan simulasi CFD untuk memprediksi karakteristik aerodinamika dan fenomena aliran yang terjadi. Model yang digunakan adalah sayap pesawat LSU-05 tanpa vortex generator dan dengan vortex generator yang didesain dengan software CATIA. Simulasi menggunakan software ANSYS Fluent untuk mengetahui perubahan karakteristik aerodinamika sayap setelah penambahan vortex generator seperti koefisien lift dan koefisien drag. Hasil yang diperoleh dari penelitian penambahan vortex generator pada sayap Pesawat LSU-05 adalah peningkatan nilai koefisien lift maksimum sayap dari 1,26450 menjadi 1,34840 atau naik sebesar 0,0839 (6,63%), peningkatan nilai koefisien drag pada sudut serang -9⁰ s/d 11⁰, penurunan nilai koefisien drag pada sudut serang 12⁰ s.d 15⁰ dan peningkatan sudut stall sayap dari 11⁰ menjadi 14⁰ atau naik sebesar 3⁰ (27,7 %).

Numerical Simulation of the Three Component Coefficients of Bridge

2012 ◽  
Vol 430-432 ◽  
pp. 2004-2007
Author(s):  
Yi Feng Huang ◽  
Ji Xin Yang
Keyword(s):  
Numerical Simulation ◽  
Wind Speed ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Moment Coefficient ◽  
Pitch Moment ◽  
Airflow Field ◽  
Bridge Girder

Numerical simulation has been carried out on the airflow field of bridge girder at construction state and completed bridge state under different wind speed and different wind angle of attack. The k-ε two-equation turbulence model is used in the numerical simulation by FLUENT. Variation of the three component coefficients can be obtained. The results show that drag coefficient and lift coefficient gradually becomes smaller and tends to stabilize, while pitch moment coefficient shows the trend of first increased and then reduced as wind speed increases. Drag coefficient and pitch moment coefficient does not change much and lift coefficient gradually becomes smaller with the change of wind angle of attack.

Effects of wavelength and amplitude of a wavy cylinder in cross-flow at low Reynolds numbers

2009 ◽  
Vol 620 ◽  
pp. 195-220 ◽  
Author(s):  
K. LAM ◽  
Y. F. LIN
Keyword(s):  
Reynolds Number ◽  
Laminar Flow ◽  
Circular Cylinder ◽  
Drag Coefficient ◽  
Shear Layer ◽  
Lift Coefficient ◽  
Three Dimensional ◽  
Spanwise Direction ◽  
Free Shear Layer ◽  
The Mean

Three-dimensional numerical simulations of laminar flow around a circular cylinder with sinusoidal variation of cross-section along the spanwise direction, named ‘wavy cylinder’, are performed. A series of wavy cylinders with different combinations of dimensionless wavelength (λ/Dm) and wave amplitude (a/Dm) are studied in detail at a Reynolds number of Re = U∞Dm/ν = 100, where U∞ is the free-stream velocity and Dm is the mean diameter of a wavy cylinder. The results of variation of mean drag coefficient and root mean square (r.m.s.) lift coefficient with dimensionless wavelength show that significant reduction of mean and fluctuating force coefficients occurs at optimal dimensionless wavelengths λ/Dm of around 2.5 and 6 respectively for the different amplitudes studied. Based on the variation of flow structures and force characteristics, the dimensionless wavelength from λ/Dm = 1 to λ/Dm = 10 is classified into three wavelength regimes corresponding to three types of wake structures. The wake structures at the near wake of different wavy cylinders are captured. For all wavy cylinders, the flow separation line varies along the spanwise direction. This leads to the development of a three-dimensional free shear layer with periodic repetition along the spanwise direction. The three-dimensional free shear layer of the wavy cylinder is larger and more stable than that of the circular cylinder, and in some cases the free shear layer even does not roll up into a mature vortex street behind the cylinder. As a result, the mean drag coefficients of some of the typical wavy cylinders are less than that of a corresponding circular cylinder with a maximum drag coefficient reduction up to 18%. The r.m.s. lift coefficients are greatly reduced to practically zero at optimal wavelengths. In the laminar flow regime (60 ≤ Re ≤ 150), the values of optimal wavelength are Reynolds number dependent.

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