**Commenced**in January 2007

**Frequency:**Monthly

**Edition:**International

**Paper Count:**419

# Search results for: circular cylinder

##### 419 Statistical Description in the Turbulent Near Wake of a Rotating Circular Cylinder

**Authors:**
Sharul S. Dol,
U. Azimov,
Robert J. Martinuzzi

**Abstract:**

**Keywords:**
Rotating circular cylinder,
Reynolds stress,
vortex.

##### 418 Experimental Measurements of Mean and Turbulence Quantities behind the Circular Cylinder by Attaching Different Number of Tripping Wires

**Authors:**
Amir Bak Khoshnevis,
Mahdieh Khodadadi,
Aghil Lotfi

**Abstract:**

For a bluff body, roughness elements in simulating a turbulent boundary layer, leading to delayed flow separation, a smaller wake, and lower form drag. In the present work, flow past a circular cylinder with using tripping wires is studied experimentally. The wind tunnel used for modeling free stream is open blow circuit (maximum speed = 30m/s and maximum turbulence of free stream = 0.1%). The selected Reynolds number for all tests was constant (Re = 25000). The circular cylinder selected for this experiment is 20 and 400mm in diameter and length, respectively. The aim of this research is to find the optimal operation mode. In this study installed some tripping wires 1mm in diameter, with a different number of wires on the circular cylinder and the wake characteristics of the circular cylinder is studied. Results showed that by increasing number of tripping wires attached to the circular cylinder (6, 8, and 10, respectively), The optimal angle for the tripping wires with 1mm in diameter to be installed on the cylinder is 60̊ (or 6 wires required at angle difference of 60̊). Strouhal number for the cylinder with tripping wires 1mm in diameter at angular position 60̊ showed the maximum value.

**Keywords:**
Wake of a circular cylinder,
trip wire,
velocity defect,
Strouhal number.

##### 417 On the Numerical Simulation of Flow Past an Oscillating Circular Cylinder in a Circular Path: Oscillation Amplitude Effect

**Authors:**
Qasem M. Al-Mdallal

**Abstract:**

**Keywords:**
Lock-on; streamwise oscillation; transverse
oscillation; fluid forces,
combined motion

##### 416 Numerical Analysis of Flow past Circular Cylinder with Triangular and Rectangular Wake Splitter

**Authors:**
Pavan Badami,
Vivek Shrivastava,
Saravanan V.,
Nandeesh Hiremath,
K. N. Seetharamu

**Abstract:**

**Keywords:**
Coefficient of drag and pressure,
CFDFLUENT,
Triangular and rectangular wake splitter,
wake length.

##### 415 Experimental and Numerical Studies of Drag Reduction on a Circular Cylinder

**Authors:**
A.O. Ladjedel,
B.T.Yahiaoui,
C.L.Adjlout,
D.O.Imine

**Abstract:**

**Keywords:**
Circular cylinder,
Drag,
grooves,
pressure
distribution

##### 414 Investigation of Self-Similarity Solution for Wake Flow of a Cylinder

**Authors:**
A. B. Khoshnevis,
F. Zeydabadi,
F. Sokhanvar

**Abstract:**

**Keywords:**
Self-similarity,
wake of single circular cylinder

##### 413 Vortex-Induced Vibration Characteristics of an Elastic Circular Cylinder

**Authors:**
T. Li,
J.Y. Zhang,
W.H. Zhang,
M.H. Zhu

**Abstract:**

**Keywords:**
Fluid-structure interaction,
Navier-Stokes equation,
Space-time finite element method,
vortex-induced vibration.

##### 412 Analysis of the Secondary Stationary Flow Around an Oscillating Circular Cylinder

**Authors:**
Artem Nuriev,
Olga Zaitseva

**Abstract:**

This paper is devoted to the study of a viscous incompressible flow around a circular cylinder performing harmonic oscillations, especially the steady streaming phenomenon. The research methodology is based on the asymptotic explanation method combined with the computational bifurcation analysis. The research approach develops Schlichting and Wang decomposition method. Present studies allow to identify several regimes of the secondary streaming with different flow structures. The results of the research are in good agreement with experimental and numerical simulation data.

**Keywords:**
Oscillating cylinder,
Secondary Streaming,
Flow
Regimes,
Asymptotic and Bifurcation Analysis.

##### 411 Experimental and Numerical Study of The Shock-Accelerated Elliptic Heavy Gas Cylinders

**Authors:**
Jing S. Bai,
Li Y. Zou,
Tao Wang,
Kun Liu,
Wen B. Huang,
Jin H. Liu,
Ping Li,
Duo W. Tan,
CangL. Liu

**Abstract:**

**Keywords:**
About four key words or phrases in alphabeticalorder,
separated by commas.

##### 410 Multiscale Structures and Their Evolution in a Screen Cylinder Wake

**Authors:**
Azlin M. Azmi,
T. Zhou,
A. Rinoshika,
L. Cheng

**Abstract:**

The turbulent structures in the wake (*x/d *=10 to 60) of a screen cylinder have been educed to understand the roles of the various structures as evolving downstream by comparing with those obtained in a solid circular cylinder wake at Reynolds number, *Re *of 7000. Using a wavelet multiresolution technique, the flow structures are decomposed into a number of wavelet components based on their central frequencies. It is observed that in the solid cylinder wake, large-scale structures (of frequency*f _{0}* and 1.2

*f*) make the largest contribution to the Reynolds stresses although they start to lose their roles significantly at

_{0}*x/d*> 20. In the screen cylinder wake, the intermediate-scale structures (2

*f*and 4

_{0 }*f*) contribute the most to the Reynolds stresses at

_{0}*x/d*=10 before being taken over by the large-scale structures (

*f*) further downstream.

_{0}**Keywords:**
Turbulent structure,
screen cylinder,
vortex,
wavelet multiresolution analysis.

##### 409 A Transform-Free HOC Scheme for Incompressible Viscous Flow past a Rotationally Oscillating Circular Cylinder

**Authors:**
Rajendra K. Ray,
H. V. R. Mittal

**Abstract:**

**Keywords:**
HOC,
Navier-Stokes,
non-uniform polar grids,
rotationally oscillating cylinder.

##### 408 Influences of Thermal Relaxation Times on Generalized Thermoelastic Longitudinal Waves in Circular Cylinder

**Authors:**
Fatimah A. Alshaikh

**Abstract:**

This paper is concerned with propagation of thermoelastic longitudinal vibrations of an infinite circular cylinder, in the context of the linear theory of generalized thermoelasticity with two relaxation time parameters (Green and Lindsay theory). Three displacement potential functions are introduced to uncouple the equations of motion. The frequency equation, by using the traction free boundary conditions, is given in the form of a determinant involving Bessel functions. The roots of the frequency equation give the value of the characteristic circular frequency as function of the wave number. These roots, which correspond to various modes, are numerically computed and presented graphically for different values of the thermal relaxation times. It is found that the influences of the thermal relaxation times on the amplitudes of the elastic and thermal waves are remarkable. Also, it is shown in this study that the propagation of thermoelastic longitudinal vibrations based on the generalized thermoelasticity can differ significantly compared with the results under the classical formulation. A comparison of the results for the case with no thermal effects shows well agreement with some of the corresponding earlier results.

**Keywords:**
Wave propagation,
longitudinal vibrations,
circular
cylinder,
generalized thermoelasticity,
Thermal relaxation times.

##### 407 Heat Transfer from Two Cam Shaped Cylinders in Tandem Arrangement

**Authors:**
Arash Mir Abdolah Lavasani,
Hamidreza Bayat

**Abstract:**

Heat transfer from two cam shape cylinder in tandem arrangement had been studied numerically. The distance between the centers of cylinders (L) is allowed to vary to change the longitudinal pitch ratio (L/Deq). The equivalent diameter of the cylinder (Deq) is 27.6 mm and longitudinal pitch ratio varies in range 2<L/Deq<6. The Reynolds number based on equivalent circular cylinder are within 50< Reeq <300. Results show that Nusselt number of second cylinder increases about 5 to 33 times when longitudinal pitch ratio increases from 2 to 6.

**Keywords:**
Cam Shaped,
tandem Cylinders,
Numerical,
Heat
Transfer.

##### 406 Weakened Vortex Shedding from a Rotating Cylinder

**Authors:**
Sharul S. Dol

**Abstract:**

An experimental study of the turbulent near wake of a rotating circular cylinder was made at a Reynolds number of 2000 for velocity ratios, *λ *between 0 and 2.7. Particle image velocimetry data are analyzed to study the effects of rotation on the flow structures behind the cylinder. The results indicate that the rotation of the cylinder causes significant changes in the vortex formation. Kármán vortex shedding pattern of alternating vortices gives rise to strong periodic fluctuations of a vortex street for *λ *< 2.0. Alternate vortex shedding is weak and close to being suppressed at *λ *= 2.0 resulting a distorted street with vortices of alternating sense subsequently being found on opposite sides. Only part of the circulation is shed due to the interference in the separation point, mixing in the base region, re-attachment, and vortex cut-off phenomenon. Alternating vortex shedding pattern diminishes and completely disappears when the velocity ratio is 2.7. The shed vortices are insignificant in size and forming a single line of vortex street. It is clear that flow asymmetries will deteriorate vortex shedding, and when the asymmetries are large enough, total inhibition of a periodic street occurs.

**Keywords:**
Circulation,
particle image velocimetry,
rotating circular cylinder,
smoke-wire flow visualization,
Strouhal number,
vortex shedding,
vortex street.

##### 405 Axisymmetric Vibration of Pyrocomposite Hollow Cylinder

**Authors:**
V. K. Nelson,
S. Karthikeyan

**Abstract:**

**Keywords:**
Axisymmetric vibration,
CFRP,
hollow cylinders,
LEMV,
pyrocomposite

##### 404 Effect of Prandtl Number on Natural Convection Heat Transfer from a Heated Semi-Circular Cylinder

**Authors:**
Avinash Chandra,
R. P. Chhabra

**Abstract:**

**Keywords:**
Constant heat flux,
Constant surface temperature,
Grashof number,
natural convection,
Prandtl number,
Semi-circular
cylinder

##### 403 Experimental Study of Frequency Behavior for a Circular Cylinder behind an Airfoil

**Authors:**
S. Bajalan,
A. Shadaram,
N. Hedayat,
A. Shams Taleghani

**Abstract:**

**Keywords:**
Airfoil,
Cylinder,
Strouhal,
Wake interaction

##### 402 Heat Transfer from Two Cam Shaped Cylinders in Side-by-Side Arrangement

**Authors:**
Arash Mir Abdolah Lavasani,
Hamidreza Bayat

**Abstract:**

**Keywords:**
Cam shaped,
side-by-side cylinders,
numerical,
heat
Transfer.

##### 401 Dynamic Variational Multiscale LES of Bluff Body Flows on Unstructured Grids

**Authors:**
Carine Moussaed,
Stephen Wornom,
Bruno Koobus,
Maria Vittoria Salvetti,
Alain Dervieux,

**Abstract:**

**Keywords:**
variational multiscale LES,
dynamic SGS model,
unstructured
grids,
circular cylinder,
square cylinder.

##### 400 Vortex Shedding on Combined Bodies at Incidence to a Uniform Air Stream

**Authors:**
T. Yavuz,
Y. E. Akansu,
M. Sarıoglu,
M. Ozmert

**Abstract:**

**Keywords:**
Bluff body,
vortex shedding,
flow separation,
flow reattachment

##### 399 Heat Transfer from a Cylinder in Cross-Flow of Single and Multiphase Flows

**Authors:**
F. A. Hamad,
S. He

**Abstract:**

**Keywords:**
Circular cylinder,
cross-flow,
heat transfer,
multicomponent multiphase flow.

##### 398 Mixed Convection Enhancement in a 3D Lid-Driven Cavity Containing a Rotating Cylinder by Applying an Artificial Roughness

**Authors:**
Ali Khaleel Kareem,
Shian Gao,
Ahmed Qasim Ahmed

**Abstract:**

**Keywords:**
Artificial roughness,
Lid-driven cavity,
Mixed convection heat transfer,
Rotating cylinder,
URANS method.

##### 397 Flow Control around Bluff Bodies by Attached Permeable Plates

**Authors:**
G. M. Ozkan,
H. Akilli

**Abstract:**

The aim of present study is to control the unsteady flow structure downstream of a circular cylinder by use of attached permeable plates. Particle image velocimetry (PIV) technique and dye visualization experiments were performed in deep water and the flow characteristics were evaluated by means of time-averaged streamlines, Reynolds Shear Stress and Turbulent Kinetic Energy concentrations. The permeable plate was made of a chrome-nickel screen having a porosity value of β=0.6 and it was attached on the cylinder surface along its midspan. Five different angles were given to the plate (θ=0^{o}, 15^{o}, 30^{o}, 45^{o}, 60^{o}) with respect to the centerline of the cylinder in order to examine its effect on the flow control. It was shown that the permeable plate is effective on elongating the vortex formation length and reducing the fluctuations in the wake region. Compared to the plain cylinder, the reductions in the values of maximum Reynolds shear stress and Turbulent Kinetic Energy were evaluated as 72.5% and 66%, respectively for the plate angles of θ=45^{o}and 60^{o} which were also found to be suggested for applications concerning the vortex shedding and consequent Vortex-Induced Vibrations.

**Keywords:**
Bluff body,
flow control,
permeable plate,
PIV,
VIV,
vortex shedding.

##### 396 Analyses of Natural Convection Heat Transfer from a Heated Cylinder Mounted in Vertical Duct

**Authors:**
H. Bhowmik,
A. Faisal,
Ahmed Al Yaarubi,
Nabil Al Alawi

**Abstract:**

Experiments are conducted to analyze the steady-state and the power-on transient natural convection heat transfer from a horizontal cylinder mounted in a vertical up flow circular duct. The heat flux ranges from 177 W/m^{2} to 2426 W/m^{2} and the Rayleigh number ranges from 1×10^{4} to 4.35×10^{4}. For natural air flow and constant heat flux condition, the effects of heat transfer around the cylinder under steady-state condition are investigated. The steady-state results compare favorably with that of the available data. The effects of transient heat transfer data on different angular position of the thermocouple (0^{o}, 90^{o}, 180^{o}) are also reported. It is observed that the transient heat transfer around the cylinder is strongly affected by the position of thermocouples. In the transient region, the rate of heat transfer obtained at 90^{o} and 180^{o} are higher than that of stagnation point (0^{o}). Finally, the dependence of the average Nusselt number on Rayleigh number for steady and transient natural convection heat transfer are analyzed, and a correlation equation is presented.

**Keywords:**
Steady-state,
transient,
natural convection,
Rayleigh number,
Nusselt number,
Fourier Number.

##### 395 Dynamics of a Vapour Bubble inside a Vertical Rigid Cylinder with a Deposit Rib

**Authors:**
S. Mehran,
S. Rouhi,
F.Rouzbahani,
E. Haghgoo

**Abstract:**

**Keywords:**
Vapour bubble,
Vertical rigid cylinder,
Boundaryelement method.

##### 394 Contribution to Active and Passive Control of Flow around a Cylinder

**Authors:**
M. Tahar Bouzaher

**Abstract:**

This numerical study aims to develop a coupled, passive and active control strategy of the flow around a cylinder of diameter D, and Re=4000. The strategy consists to put a cylindrical rod in front of a deforming cylinder. The quasi- elliptical deformation of cylinder follow a sinusoidal law in order to reduce the drag force. To analyze the evolution of unsteady vortices, the Large Eddy Simulation approach is used in this 2D simulation, carried out using ANSYS – Fluent. The movement of deformation is reproduced using an internal subroutine, introduced in the form of a User Defined Function UDF. Two diameters of the rod were tested for a rod placed at a distance L = 3 ×d, with an amplitudes of deformation A = 5%, A = 25% and A = 50% of the cylinder diameter, the frequency of deformation take the values fd = 1fn, 5fn and 8fn, which fn represents the naturel vortex shedding frequency. The results show substantial changes in the flow behavior and for a rod of 6mm (1% D) with amplitude A = 25%, and with a 2fn frequency, drag reduction of 60% was recorded.

**Keywords:**
CFD,
Flow separation,
control,
Boundary layer,
rod,
Cylinder.

##### 393 Application of Metakaolin from Northeast of Thailand Used as Binder in Casting Process of Rice Polishing Cylinder

**Authors:**
T. Boonkang,
C. Santhaweesuk,
N. Pianthong,
P. Neeramon,
A. Phimhlo,
S. Bangphan

**Abstract:**

**Keywords:**
Binder,
casting,
metakaolin,
rice polishing cylinder.

##### 392 Fourth Order Accurate Free Convective Heat Transfer Solutions from a Circular Cylinder

**Authors:**
T. V. S. Sekhar,
B. Hema Sundar Raju

**Abstract:**

**Keywords:**
Higher order compact scheme,
Navier-Stokes
equations,
Energy equation,
Natural convection,
Boussinesq's
approximation and Mean Nusselt number.

##### 391 Bond Graph Modeling of Inter-Actuator Interactions in a Multi-Cylinder Hydraulic System

**Authors:**
Mutuku Muvengei,
John Kihiu

**Abstract:**

**Keywords:**
Bond graphs,
Inter-actuator interactions,
Valvecontrolledhydraulic cylinder.

##### 390 Non-Circular Carbon Fiber Reinforced Polymers Chainring Failure Analysis

**Authors:**
A. Elmikaty,
Z. Thanawarothon,
L. Mezeix

**Abstract:**

This paper presents a finite element model to simulate the teeth failure of non-circular composite chainring. Model consists of the chainring and a part of the chain. To reduce the size of the model, only the first 11 rollers are simulated. In order to validate the model, it is firstly applied to a circular aluminum chainring and evolution of the stress in the teeth is compared with the literature. Then, effect of the non-circular shape is studied through three different loading positions. Strength of non-circular composite chainring and failure scenario is investigated. Moreover, two composite lay-ups are proposed to observe the influence of the stacking. Results show that composite material can be used but the lay-up has a large influence on the strength. Finally, loading position does not have influence on the first composite failure that always occurs in the first tooth.

**Keywords:**
CFRP,
composite failure,
FEA,
non-circular chainring.