Prediction of Vortex Shedding Control by Means of Splitter Plates

2017 ◽  
Author(s):  
Shaoshi Dai ◽  
Rongyu Zhang ◽  
Bassam A. Younis ◽  
Hongyang Zhang
Keyword(s):  
Vortex Shedding ◽  
Computational Study ◽  
Circular Cylinders ◽  
Maximum Reduction ◽  
Drag Forces ◽  
Splitter Plates ◽  
High Reynolds ◽  
Lift And Drag ◽  
Main Effects ◽  
Plate Width

The paper presents preliminary results of a computational study aimed at quantifying the effectiveness of splitter plates in reducing the strength of vortex shedding from circular cylinders at high Reynolds number. The principal interest is in determining the optimal ratio of splitter plate width to cylinder diameter to achieve maximum reduction in the magnitude of the fluctuating lift and drag forces relative to their original values. The computations were performed using the URANS approach. The effects of turbulence were accounted for using a turbulence closure that has been adapted to account for the effects of organized vortex shedding on the random turbulent motions. Comparisons with experimental data show that this approach is successful in capturing the main effects that arise from the attachment of splitter plates to the cylinder base.

On the Suppression of Vortex Shedding From Circular Cylinders Using Detached Short Splitter-Plates

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Behzad Ghadiri Dehkordi ◽  
Hamed Houri Jafari
Keyword(s):  
Circular Cylinder ◽  
Vortex Shedding ◽  
Splitter Plate ◽  
Circular Cylinders ◽  
Staggered Grid ◽  
Drag Forces ◽  
Splitter Plates ◽  
Parallel Arrangement ◽  
Lift And Drag ◽  
Good Agreement

Flow over a circular cylinder with detached short splitter-plates is numerically simulated in order to assess the suppression of periodic vortex shedding. A finite-volume solver based on the Cartesian-staggered grid is implemented, and the ghost-cell method in conjunction with Great-Source-Term technique is employed in order to enforce directly the no-slip condition on the cylinder boundary. The accuracy of the solver is validated by simulation of the flow around a single circular cylinder. The results are in good agreement with the experimental data reported in the literature. Finally, the flows over a circular cylinder with splitter-plate in its downstream (off and on the centerline) are computed in Re=40 as a nonvortex shedding case and in Re=100 and 150 as cases with vortex shedding effects. The same simulations are also performed for the case where dual splitter-plates are in a parallel arrangement embedded in the downstream of the cylinder. The optimum location of the splitter-plate to achieve maximum reduction in the lift and drag forces is determined.

scholarly journals Prediction of Turbulent Flow Around a Square Cylinder With Rounded Corners

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
S. S. Dai ◽  
B. A. Younis ◽  
H. Y. Zhang
Keyword(s):  
Turbulent Flow ◽  
Vortex Shedding ◽  
Turbulence Closure ◽  
Navier Stokes ◽  
Square Cylinder ◽  
Mean Flow ◽  
Drag Forces ◽  
Turbulence Closures ◽  
High Reynolds ◽  
Lift And Drag

Predictions are reported of the two-dimensional turbulent flow around a square cylinder with rounded corners at high Reynolds numbers. The effects of rounded corners have proved difficult to predict with conventional turbulence closures, and hence, the adoption in this study of a two-equation closure that has been specifically adapted to account for the interactions between the organized mean-flow motions due to vortex shedding and the random motions due to turbulence. The computations were performed using openfoam and were validated against the data from flows past cylinders with sharp corners. For the case of rounded corners, only the modified turbulence closure succeeded in capturing the consequences of the delayed flow separation manifested mainly in the reduction of the magnitude of the lift and drag forces relative to the sharp-edged case. These and other results presented here argue in favor of the use of the computationally more efficient unsteady Reynolds-averaged Navier-Stokes approach to this important class of flows provided that the effects of vortex shedding are properly accounted for in the turbulence closure.

Numerical Analysis of Flow Over the NASA Common Research Model Using the Academic Computational Fluid Dynamics Code Galatea

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Georgios N. Lygidakis ◽  
Ioannis K. Nikolos
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Analysis ◽  
Computational Study ◽  
Research Model ◽  
Drag Forces ◽  
Efficient Prediction ◽  
Wind Tunnel Data ◽  
Computational Fluid Dynamics Cfd ◽  
Lift And Drag

A recently developed academic computational fluid dynamics (CFD) code, named Galatea, is used for the computational study of fully turbulent flow over the NASA common research model (CRM) in a wing-body configuration with and without horizontal tail. A brief description of code's methodology is included, while attention is mainly directed toward the accurate and efficient prediction of pressure distribution on wings' surfaces as well as of computation of lift and drag forces against different angles of attack, using an h-refinement approach and a parallel agglomeration multigrid scheme. The obtained numerical results compare close with both the experimental wind tunnel data and those of reference solvers.

scholarly journals The Lift and Drag Forces on Tandem Circular Cylinders Oscillating in Uniform Flow

1974 ◽  
Vol 40 (331) ◽  
pp. 765-773
Author(s):  
Yasuyuki WATANABE ◽  
Atsushi OKAJIMA ◽  
Yosimiti TANIDA
Keyword(s):  
Uniform Flow ◽  
Circular Cylinders ◽  
Drag Forces ◽  
Lift And Drag

A Computational Study of the Flow Around an Isolated Wheel in Contact With the Ground

2005 ◽  
Vol 128 (3) ◽  
pp. 520-530 ◽  
Author(s):  
James McManus ◽  
Xin Zhang
Keyword(s):  
Computational Study ◽  
Experimental Results ◽  
Navier Stokes ◽  
Flow Structures ◽  
Road Vehicles ◽  
Accurate Representation ◽  
Drag Forces ◽  
Mechanisms Of Formation ◽  
Lift And Drag ◽  
Good Agreement

The flow around an isolated wheel in contact with the ground is computed by the Unsteady Reynolds-Averaged Navier-Stokes (URANS) method. Two cases are considered, a stationary wheel on a stationary ground and a rotating wheel on a moving ground. The computed wheel geometry is a detailed and accurate representation of the geometry used in the experiments of Fackrell and Harvey. The time-averaged computed flow is examined to reveal both new flow structures and new details of flow structures known from previous experiments. The mechanisms of formation of the flow structures are explained. A general schematic picture of the flow is presented. Surface pressures and pressure lift and drag forces are computed and compared to experimental results and show good agreement. The grid sensitivity of the computations is examined and shown to be small. The results have application to the design of road vehicles.

Suppression of Fluid Forces Acting on a Square Prism by Passive Control

1997 ◽  
Vol 119 (3) ◽  
pp. 506-511 ◽  
Author(s):  
H. Sakamoto ◽  
K. Tan ◽  
N. Takeuchi ◽  
H. Haniu
Keyword(s):  
Flat Plate ◽  
Vortex Shedding ◽  
Passive Control ◽  
Fluid Forces ◽  
Maximum Reduction ◽  
Square Prism ◽  
Vortex Shedding Frequency ◽  
Shedding Frequency ◽  
Unsteady Fluid ◽  
Lift And Drag

Suppression of fluid forces acting on a square prism by passive control of the approaching flow was investigated in the present study. Flow was controlled using a small flat plate upstream of the prism. The position of the flat plate was varied within the range of S/W = 0 ~ 3.0 (S: distance between the flat plate and square prism, W: width of square prism) and the width h of the flat plate ranged from 2 mm to 8 mm (h/W = 0.05 ~ 0.19). Steady and unsteady fluid forces, vortex shedding frequency, and flow pattern were systematically investigated. The maximum reduction of time-averaged drag was 75 percent, and the maximum reduction in fluctuating lift and drag was 95 and 80 percent, respectively, using a flat plate 1/10 of the size of the square prism.

Turbine Flowmeter Performance Model

1970 ◽  
Vol 92 (4) ◽  
pp. 712-722 ◽  
Author(s):  
R. E. Thompson ◽  
J. Grey
Keyword(s):  
Reynolds Number ◽  
Velocity Profile ◽  
High Reynolds Number ◽  
Performance Model ◽  
Interference Effects ◽  
Rotor Speed ◽  
Number Range ◽  
Drag Forces ◽  
High Reynolds ◽  
Lift And Drag

A theoretical model of a turbine meter operating in the high Reynolds number regime has been formulated to study the effects of retarding torques, inlet velocity profile, blade interference effects, meter geometry, and other factors. A computer program predicts actual rotor speed by numerical integration of the lift and drag forces on the rotor blade. Numerical sample calculations indicated substantial effects due to velocity profile and blade interference. Retarding torques were relatively unimportant in the high Reynolds number range.

Computational Study of Taper Effect of a Hydrofoil at Different Reynolds Numbers on the Length of Cavity and Lift and Drag Coefficients

2009 ◽  
Author(s):  
Mohammad J. Izadi ◽  
Mahdi Mirtorabi
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Cavity Length ◽  
Computational Study ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
High Reynolds ◽  
Lift And Drag

In this paper a cavitating flow around a three dimensional tapered hydrofoil in an incompressible fluid is modeled and studied. The variables in this study are the taper ratio, angle of attack and the Reynolds number. The taper ratio changes from 0.2 to 1, the angles of attack varies from −2 to 12 degrees and all these are computed at two Reynolds numbers (Re = 5.791·107 and Re = 1.99·108). The flow is assumed to be unsteady and isothermal. Coefficients of drag and lift and also the cavity length are computed numerically. Comparing the numerical results of five investigated models (five tapered hydrofoils) and the work done by Kermeen experimentally, it can be seen that the tapered hydrofoil in some cases gave better results, reducing the cavity length and improving the lift coefficient. At the low Reynolds number, the length of the cavity is calculated to be small in comparison with the length gained at the high Reynolds number, and therefore the change of the taper and the angles of attack did change the amount of the lift coefficient as much. For high Reynolds number, as the angle of attack increased, the tapering effect became more important and the best lift coefficient and minimum cavity length is obtained at a taper ratio of 0.4 for an averaged angles of attack.

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