**Commenced**in January 2007

**Frequency:**Monthly

**Edition:**International

**Paper Count:**2380

# Search results for: Flow overthe 3D Cylinder

##### 2380 Semi-Lagrangian Method for Advection Equation on GPU in Unstructured R3 Mesh for Fluid Dynamics Application

**Authors:**
Irakli V. Gugushvili,
Nickolay M. Evstigneev

**Abstract:**

Numerical integration of initial boundary problem for advection equation in 3 ℜ is considered. The method used is conditionally stable semi-Lagrangian advection scheme with high order interpolation on unstructured mesh. In order to increase time step integration the BFECC method with limiter TVD correction is used. The method is adopted on parallel graphic processor unit environment using NVIDIA CUDA and applied in Navier-Stokes solver. It is shown that the calculation on NVIDIA GeForce 8800 GPU is 184 times faster than on one processor AMDX2 4800+ CPU. The method is extended to the incompressible fluid dynamics solver. Flow over a Cylinder for 3D case is compared to the experimental data.

**Keywords:**
Advection equations,
CUDA technology,
Flow overthe 3D Cylinder,
Incompressible Pressure Projection Solver,
Parallel computation.

##### 2379 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.

##### 2378 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

##### 2377 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.

##### 2376 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.

##### 2375 Numerical Investigation of the Effect of Flow and Heat Transfer of a Semi-Cylindrical Obstacle Located in a Channel

**Authors:**
Omer F. Can,
Nevin Celik

**Abstract:**

**Keywords:**
External flow,
semi-cylinder obstacle,
heat transfer,
friction.

##### 2374 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.

##### 2373 Hybrid RANS-LES Simulation of In-Cylinder Air Flow for Different Engine Speeds at Fixed Intake Flow Pressure

**Authors:**
L. V. Fui,
A. Ulugbek,
S. S. Dol

**Abstract:**

The in-cylinder flow and mixture formations are significant in view of today’s increasing concern on environmental issues and stringent emission regulations. In this paper, the numerical simulations of a SI engine at different engine speeds (2000-5000 rpm) at fixed intake flow pressure of 1 bar are studied using the AVL FIRE software. The simulation results show that when the engine speed at fixed intake flow pressure is increased, the volumetric efficiency of the engine decreases. This is due to a richer fuel conditions near the engine cylinder wall when engine speed is increased. Significant effects of impingement are also noted on the upper and side walls of the engine cylinder. These variations in mixture formation before ignition could affect the thermodynamics efficiency and specific fuel consumption that would lead to a reduced engine performance.

**Keywords:**
AVL FIRE,
fuel mass,
IC engine,
LES,
RANS,
turbulent intensity.

##### 2372 Effects of Injection Velocity and Entrance Airflow Velocity on Droplets Sizing in a Duct

**Authors:**
M. M. Doustdar ,
M. Mojtahedpoor

**Abstract:**

**Keywords:**
Ramjet,
droplet sizing,
injection velocity,
air flow
velocity,
efficient mass fraction.

##### 2371 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.

##### 2370 Numerical Analysis of Laminar Flow around Square Cylinders with EHD Phenomenon

**Authors:**
M. Salmanpour,
O. Nourani Zonouz

**Abstract:**

In this research, a numerical simulation of an Electrohydrodynamic (EHD) actuator’s effects on the flow around a square cylinder by using a finite volume method has been investigated. This is one of the newest ways for controlling the fluid flows. Two plate electrodes are flush-mounted on the surface of the cylinder and one wire electrode is placed on the line with zero angle of attack relative to the stagnation point and excited with DC power supply. The discharge produces an electric force and changes the local momentum behaviors in the fluid layers. For this purpose, after selecting proper domain and boundary conditions, the electric field relating to the problem has been analyzed and then the results in the form of electrical body force have been entered in the governing equations of fluid field (Navier-Stokes equations). The effect of ionic wind resulted from the Electrohydrodynamic actuator, on the velocity, pressure and the wake behind cylinder has been considered. According to the results, it is observed that the fluid flow accelerates in the nearest wall of the frontal half of the cylinder and the pressure difference between frontal and hinder cylinder is increased.

**Keywords:**
CFD,
corona discharge,
electro hydrodynamics,
flow around square cylinders.

##### 2369 An Investigation on the Effects of Injection Spray Cone on Propulsive Droplets in a Duct

**Authors:**
M. Mojtahedpoor

**Abstract:**

**Keywords:**
Ramjet,
droplet sizing,
injection velocity,
air flowvelocity,
efficient mass fraction..

##### 2368 Experimental Investigations of a Modified Taylor-Couette Flow

**Authors:**
A. Esmael,
A. El Shrif

**Abstract:**

In this study the instability problem of a modified Taylor-Couette flow between two vertical coaxial cylinders of radius R1, R2 is considered. The modification is based on the wavy shape of the inner cylinder surface, where inner cylinders with different surface amplitude and wavelength are used. The study aims to discover the effect of the inner surface geometry on the instability phenomenon that undergoes Taylor-Couette flow. The study reveals that the transition processes depends strongly on the amplitude and wavelength of the inner cylinder surface and resulting in flow instabilities that are strongly different from that encountered in the case of the classical Taylor-Couette flow.

**Keywords:**
Hydrodynamic Instability,
Modified Taylor-Couette
Flow,
Turbulence,
Taylor vortices.

##### 2367 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.

##### 2366 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.

##### 2365 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.

##### 2364 Tumble Flow Analysis in an Unfired Engine Using Particle Image Velocimetry

**Authors:**
B. Murali Krishna,
J. M. Mallikarjuna

**Abstract:**

**Keywords:**
In-cylinder flow,
Dome piston,
Cavity,
Tumble,
PIV

##### 2363 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

##### 2362 Effect of Reynolds Number on Flow past a Square Cylinder in Presence of Upstream and Downstream Flat Plate at Small Gap Spacing

**Authors:**
Shams-ul-Islam,
Raheela Manzoor,
Zhou Chao Ying

**Abstract:**

**Keywords:**
Detached flat plates,
drag and lift coefficients,
Reynolds numbers,
square cylinder,
Strouhal number.

##### 2361 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.

##### 2360 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.

##### 2359 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.

##### 2358 Numerical Simulation of Flow and Combustionin an Axisymmetric Internal Combustion Engine

**Authors:**
Nureddin Dinler,
Nuri Yucel

**Abstract:**

**Keywords:**
CFD simulation,
eddy break-up model,
k-εturbulence model,
reciprocating engine flow and combustion.

##### 2357 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

##### 2356 Dynamics of a Vapour Bubble inside a Vertical Rigid Cylinder in the Absence of Buoyancy Forces

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

**Abstract:**

**Keywords:**
Vapour bubble,
Vertical rigid cylinder,
Boundaryelement method,
Finite difference method,
Buoyancy forces.

##### 2355 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.

##### 2354 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

##### 2353 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.

##### 2352 Heat Transfer Dependent Vortex Shedding of Thermo-Viscous Shear-Thinning Fluids

**Authors:**
Markus Rütten,
Olaf Wünsch

**Abstract:**

**Keywords:**
Heat transfer,
thermo-viscous fluids,
shear thinning,
vortex shedding.

##### 2351 Grid Independence Study of Flow Past a Square Cylinder Using the Multi-Relaxation-Time Lattice Boltzmann Method

**Authors:**
Shams-Ul-Islam,
Hamid Rahman,
Waqas Sarwar Abbasi

**Abstract:**

Numerical calculations of flow around a square cylinder are presented using the multi-relaxation-time lattice Boltzmann method at Reynolds number 150. The effects of upstream locations, downstream locations and blockage are investigated systematically. A detail analysis are given in terms of time-trace analysis of drag and lift coefficients, power spectra analysis of lift coefficient, vorticity contours visualizations and phase diagrams. A number of physical quantities mean drag coefficient, drag coefficient, Strouhal number and root-mean-square values of drag and lift coefficients are calculated and compared with the well resolved experimental data and numerical results available in open literature. The results had shown that the upstream, downstream and height of the computational domain are at least 7.5, 37.5 and 12 diameters of the cylinder, respectively.

**Keywords:**
Grid independence,
Multi-relaxation-time lattice Boltzmann method,
Physical quantities,
Square cylinder,
Vorticity contours visualizations.