**Commenced**in January 2007

**Frequency:**Monthly

**Edition:**International

**Paper Count:**69

# Search results for: near wake.

##### 69 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.

##### 68 Alternative Approach in Ground Vehicle Wake Analysis

**Authors:**
L. Sterken,
S. Sebben,
L. Löfdahl

**Abstract:**

**Keywords:**
Coordinate transformation,
ground vehicle,
local
drag,
wake.

##### 67 Effect of Amplitude and Mean Angle of Attack on Wake of an Oscillating Airfoil

**Authors:**
Sadeghi H.,
Mani M.,
Ardakani M. A.

**Abstract:**

**Keywords:**
Unsteady wake,
amplitude,
mean angle,
EPPLER
361 airfoil.

##### 66 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.

##### 65 Image Analysis of Fine Structures of Supercavitation in the Symmetric Wake of a Cylinder

**Authors:**
Y. Obikane ,
M.Kaneko,
K.Kakioka,
K.Ogura

**Abstract:**

**Keywords:**
Supercavitation,
density gradient correlation

##### 64 Airliner-UAV Flight Formation in Climb Regime

**Authors:**
Pavel Zikmund,
Robert Popela

**Abstract:**

**Keywords:**
Flight in formation,
self-sustained flight,
UAV,
wake
vortex.

##### 63 Ginzburg-Landau Model : an Amplitude Evolution Equation for Shallow Wake Flows

**Authors:**
Imad Chaddad,
Andrei A. Kolyshkin

**Abstract:**

**Keywords:**
Ginzburg-Landau equation,
shallow wake flow,
weakly nonlinear theory.

##### 62 Study of Aerodynamic Characteristics of the Unmanned Aircraft in the Wake

**Authors:**
O. Solovyov,
S. Eryomenko,
V. Kobrin,
V. Chmovzh

**Abstract:**

The methodology of numerical simulation and calculation of aerodynamic characteristics of aircraft taking into account impact of wake on it has been developed. The results of numerical experiment in comparison with the data obtained in the wind tunnel are presented. Efficiency of methodology of calculation and the reliability of the results is shown.

**Keywords:**
Unmanned aircraft,
vortex wake,
aerodynamic characteristics.

##### 61 Characterization of the Near-Wake of an Ahmed Body Profile

**Authors:**
Stéphanie Pellerin,
Bérengére Podvin,
Luc Pastur

**Abstract:**

**Keywords:**
Ahmed body,
bi-stability,
LES,
near wake.

##### 60 A Vortex Plate Theory of Hovering Animal Flight

**Authors:**
Khaled. M. Faqih

**Abstract:**

**Keywords:**
vortex theory,
hovering flight,
induced power,
Prandlt's tip theory.

##### 59 Unsteady Aerodynamics of Multiple Airfoils in Configuration

**Authors:**
Hossain Aziz,
Rinku Mukherjee

**Abstract:**

**Keywords:**
Aerodynamics,
Airfoils,
Configuration,
Unsteady.

##### 58 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

##### 57 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

##### 56 Using the V-Sphere Code for the Passive Scalar in the Wake of a Bluff Body

**Authors:**
Y. Obikane,
T. Nemoto ,
K. Ogura,
M. Iwata,
K. Ono

**Abstract:**

The objective of this research was to find the diffusion properties of vehicles on the road by using the V-Sphere Code. The diffusion coefficient and the size of the height of the wake were estimated with the LES option and the third order MUSCL scheme. We evaluated the code with the changes in the moments of Reynolds Stress along the mean streamline. The results show that at the leading part of a bluff body the LES has some advantages over the RNS since the changes in the strain rates are larger for the leading part. We estimated that the diffusion coefficient with the computed Reynolds stress (non-dimensional) was about 0.96 times the mean velocity.

**Keywords:**
Wake ,
bluff body,
V-CAD,
turbulence diffusion.

##### 55 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.

##### 54 Linear Instability of Wake-Shear Layers in Two-Phase Shallow Flows

**Authors:**
Inta Volodko,
Valentina Koliskina

**Abstract:**

**Keywords:**
Linear stability,
Shallow flows,
Wake-shear flows.

##### 53 Linear Stability Characteristics of Wake-Shear Layers in Two-Phase Shallow Flows

**Authors:**
Inta Volodko,
Valentina Koliskina

**Abstract:**

**Keywords:**
Linear stability,
Shallow flows,
Wake-shear flows.

##### 52 Unsteady 3D Post-Stall Aerodynamics Accounting for Effective Loss in Camber Due to Flow Separation

**Authors:**
Aritras Roy,
Rinku Mukherjee

**Abstract:**

**Keywords:**
Post-stall,
unsteady,
wing,
aerodynamics.

##### 51 Shear Layer Investigation through a High-Load Cascade in Low-Pressure Gas Turbine Conditions

**Authors:**
Mehdi Habibnia Rami,
Shidvash Vakilipour,
Mohammad H. Sabour,
Rouzbeh Riazi,
Hossein Hassannia

**Abstract:**

This paper deals with the steady and unsteady flow behavior on the separation bubble occurring on the rear portion of the suction side of T106A blade. The first phase was to implement the steady condition capturing the separation bubble. To accurately predict the separated region, the effects of three different turbulence models and computational grids were separately investigated. The results of Large Eddy Simulation (LES) model on the finest grid structure are acceptably in a good agreement with its relevant experimental results. The second phase is mainly to address the effects of wake entrance on bubble disappearance in unsteady situation. In the current simulations, from what was suggested in an experiment, simulating the flow unsteadiness, with concentrations on small scale disturbances instead of simulating a complete oncoming wake, is the key issue. Subsequently, the results from the current strategy to apply the effects of the wake and two other experimental work were compared to be in a good agreement. Between the two experiments, one of them deals with wake passing unsteady flow, and the other one implements experimentally the same approach as the current Computational Fluid Dynamics (CFD) simulation.

**Keywords:**
T106A turbine cascade,
shear-layer separation,
steady and unsteady conditions,
turbulence models,
OpenFOAM.

##### 50 Influence of After Body Shape on the Performance of Blunt Shaped Bodies as Vortex Shedders

**Authors:**
Lavish Ordia,
A. Venugopal,
Amit Agrawal,
S. V. Prabhu

**Abstract:**

The present study explores flow visualization experiments with various blunt shaped bluff bodies placed inside a circular pipe. The bodies mainly comprise of modifications of trapezoidal cylinder, most widely used in practical applications, such as vortex flowmeters. The present configuration possesses the feature of both internal and external flows with low aspect ratio. The vortex dynamics of bluff bodies in such configuration is seldom reported in the literature. Dye injection technique is employed to visualize the complex vortex formation mechanism behind the bluff bodies. The influence of orientation, slit and after body shape is studied in an attempt to obtain better understanding of the vortex formation mechanism. Various wake parameters like Strouhal number, vortex formation length and wake width are documented for these shapes. Vortex formation both with and without shear layer interaction is observed for most of the shapes.

**Keywords:**
Flow visualization,
Reynolds number,
Strouhal number,
vortex,
vortex formation length,
wake width.

##### 49 Streamwise Vorticity in the Wake of a Sliding Bubble

**Authors:**
R. O’Reilly Meehan,
D. B. Murray

**Abstract:**

**Keywords:**
Bubbly flow,
particle image velocimetry,
two-phase
flow,
wake structures.

##### 48 The Effect of Tmax in Energy Consumption in 0IEEE 802.16e with Traffic Load

**Authors:**
Mohammadreza Sahebi,
Arash Azizi Mazreah,
Asadollah Shahbahrami,
Bahram Bakhshi

**Abstract:**

**Keywords:**
IEEE 802.16e,
Sleep-mode,
Wake-mode,
Downlink,
Mobile Subscriber Station.

##### 47 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.

##### 46 Research on the Correlation of the Fluctuating Density Gradient of the Compressible Flows

**Authors:**
Yasuo Obikane

**Abstract:**

**Keywords:**
Turbulence Modeling ,
Density Gradient Correlation,
Compressible

##### 45 Generalized Vortex Lattice Method for Predicting Characteristics of Wings with Flap and Aileron Deflection

**Authors:**
Mondher Yahyaoui

**Abstract:**

A generalized vortex lattice method for complex lifting surfaces with flap and aileron deflection is formulated. The method is not restricted by the linearized theory assumption and accounts for all standard geometric lifting surface parameters: camber, taper, sweep, washout, dihedral, in addition to flap and aileron deflection. Thickness is not accounted for since the physical lifting body is replaced by a lattice of panels located on the mean camber surface. This panel lattice setup and the treatment of different wake geometries is what distinguish the present work form the overwhelming majority of previous solutions based on the vortex lattice method. A MATLAB code implementing the proposed formulation is developed and validated by comparing our results to existing experimental and numerical ones and good agreement is demonstrated. It is then used to study the accuracy of the widely used classical vortex-lattice method. It is shown that the classical approach gives good agreement in the clean configuration but is off by as much as 30% when a flap or aileron deflection of 30° is imposed. This discrepancy is mainly due the linearized theory assumption associated with the conventional method. A comparison of the effect of four different wake geometries on the values of aerodynamic coefficients was also carried out and it is found that the choice of the wake shape had very little effect on the results.

**Keywords:**
Aileron deflection,
camber-surface-bound vortices,
classical VLM,
Generalized VLM,
flap deflection.

##### 44 Vortex Wake Formation and Its Effects on Thrust and Propulsive Efficiency of an Oscillating Airfoil

**Authors:**
Ahmet Selim Durna,
Bayram Celik,
Aydin Misirlioglu

**Abstract:**

**Keywords:**
pithing and plunging airfoil,
leading edge vortex,
trailing edge vortex,
vortex interaction,
wake structure.

##### 43 Lagrangian Flow Skeletons Captured in the Wake of a Swimming Nematode C. elegans Using an Immersed Boundary Fluid-Structure Interaction Approach

**Authors:**
Arash Taheri

**Abstract:**

In this paper, Lagrangian coherent structure (LCS) concept is applied to wake flows generated in the up/down-stream of a swimming nematode C. elegans in an intermediate Re number range, i.e., 250-1200. It materializes Lagrangian hidden structures depicting flow transport barriers. To pursue the goals, nematode swimming in a quiescent fluid flow environment is numerically simulated by a two-way fluid-structure interaction (FSI) approach with the aid of immersed boundary method (IBM). In this regard, incompressible Navier-Stokes equations, fully-coupled with Lagrangian deformation equations for the immersed body, are solved using IB2d code. For all simulations, nematode’s body is modeled with a parametrized spring-fiber built-in case available in the computational code. Reverse von-Kármán vortex street formation and vortex shedding characteristics are studied and discussed in details via LCS approach, including grid resolution, integration time and Reynolds number effects. Results unveil presence of different flow regions with distinct fluid particle fates in the swimming animal’s wake and formation of so-called ‘mushroom-shaped’ structures in attracting LCS identities.

**Keywords:**
Lagrangian coherent structure,
nematode swimming,
fluid-structure interaction,
immersed boundary method,
bionics.

##### 42 The Comparison of Form Drag and Profile Dragof a Wind Turbine Blade Section in Pitching Oscillation

**Authors:**
M. R. Soltani,
M. Seddighi,
M. Mahmoudi

**Abstract:**

**Keywords:**
Pitching motion,
form drag,
Profile drag,
windturbine.

##### 41 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.

##### 40 Phase-Averaged Analysis of Three-Dimensional Vorticity in the Wake of Two Yawed Side-By-Side Circular Cylinders

**Authors:**
T. Zhou,
S. F. Mohd. Razali,
Y. Zhou,
H. Wang,
L. Cheng

**Abstract:**

Thewake flow behind two yawed side-by-sidecircular cylinders is investigated using athree-dimensional vorticity probe. Four yaw angles (α), namely, 0°, 15°, 30° and 45° and twocylinder spacing ratios T* of 1.7 and 3.0 were tested. For T* = 3.0, there exist two vortex streets and the cylinders behave as independent and isolated ones. The maximum contour value of the coherent streamwise vorticity ~* ωx is only about 10% of that of the spanwise vorticity ~* ωz . With the increase of α, ~* ωx increases whereas ~* ωz decreases. At α = 45°, ~* ωx is about 67% of ~* ωz .For T* = 1.7, only a single peak is detected in the energy spectrum. The spanwise vorticity contours have an organized pattern only at α = 0°. The maximum coherent vorticity contours of ~* ω x and ~* ωz for T* = 1.7 are about 30% and 7% of those for T* = 3.0.The independence principle (IP)in terms of Strouhal numbers is applicable in both wakes when α< 40°.

**Keywords:**
Circular cylinder wake,
vorticity,
vortex shedding.