scholarly journals Effect of NACA0012 Airfoil Pitching Oscillation on Flow Past a Cylinder

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5582
Author(s):  
Rong Han ◽  
Wei Liu ◽  
Xiao-Liang Yang ◽  
Xing-Hua Chang
Keyword(s):  
Drag Reduction ◽  
Vortex Shedding ◽  
Stokes Equations ◽  
Reduction Rate ◽  
Classical Problem ◽  
Arbitrary Lagrangian Eulerian ◽  
Tight Coupling ◽  
Naca0012 Airfoil ◽  
Flow Past ◽  
Flow Past A Cylinder

The flow past a cylinder is a classical problem in flow physics. In a certain range of Reynolds number, there will be Karman vortex street phenomenon in the wake of a cylinder, which will greatly increase the pressure drag of the cylinder. By controlling the vortex shedding phenomenon, drag reduction of the cylinder could be effectively realized. In this paper, a NACA0012 airfoil with pitching oscillation is placed downstream of the cylinder. Based on the tight coupling method, kinematics equations and Navier–Stokes equations in the arbitrary Lagrangian–Eulerian form are solved. Firstly, the effect of airfoil oscillation period and the distance between airfoil leading edge and cylinder center (x/D) are studied respectively, especially considering the aspects of vortex shedding and drag reduction effect. Besides, the vortex interaction in the flow field around the airfoil and cylinder is analyzed in detail. It is found that the NACA0012 airfoil with pitching oscillation can change the period of vortex shedding. Moreover, it can also increase the drag reduction rate to as high as 50.5%, which presents a certain application prospect in the engineering drag reduction field, e.g., for launch vehicles, ship masts, submarine pipelines, etc.

Vortex shedding and three-dimensional behaviour of flow past a cylinder confined in a channel

2011 ◽  
Vol 27 (5-6) ◽  
pp. 855-860 ◽  
Author(s):  
Martin D. Griffith ◽  
Justin Leontini ◽  
Mark C. Thompson ◽  
Kerry Hourigan
Keyword(s):  
Vortex Shedding ◽  
Three Dimensional ◽  
Flow Past ◽  
Flow Past A Cylinder

scholarly journals Computational Algorithms for Solving Spectral/$hp$ Stabilized Incompressible Flow Problems

2016 ◽  
Vol 8 (4) ◽  
pp. 21 ◽  
Author(s):  
Rakesh Ranjan ◽  
Anthony Theodore Chronopoulos ◽  
Yusheng Feng
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Higher Order ◽  
Navier Stokes ◽  
Krylov Methods ◽  
Higher Order Methods ◽  
The Past ◽  
Flow Past ◽  
Flow Past A Cylinder ◽  
Computationally Intensive

In this paper we implement the element-by-element preconditioner and inexact Newton-Krylov methods (developed in the past) for solving stabilized computational fluid dynamics (CFD) problems with spectral methods. Two different approaches are implemented for speeding up the process of solving both steady and unsteady incompressible Navier-Stokes equations. The first approach concerns the application of a scalable preconditioner namely the element by element LU preconditioner, while the second concerns the application of Newton-Krylov (NK) methods for solving non-linear problems. We obtain good agreement with benchmark results on standard CFD problems for various Reynolds numbers. We solve the Kovasznay flow and flow past a cylinder at Re-$100$ with this approach. We also utilize the Newton-Krylov algorithm to solve (in parallel) important model problems such as flow past a circular obstacle in a Newtonian flow field, three dimensional driven cavity, flow past a three dimensional cylinder with different immersion lengths. We explore the scalability and robustness of the formulations for both approaches and obtain very good speedup. Effective implementations of these procedures demonstrate for relatively coarse macro-meshes<br />the power of higher order methods in obtaining highly accurate results in CFD. While the procedures adopted in the paper have been explored in the past the novelty lies with applications with higher order methods which have been known to be computationally intensive.

Immersed Boundary Method for Simulation of Oscillatory Flow Past a Submerged Cylinder Near Above a Horizontal Bed

2014 ◽  
Author(s):  
Efstratios N. Fonias ◽  
Athanassios A. Dimas
Keyword(s):  
Reynolds Number ◽  
Immersed Boundary Method ◽  
Oscillatory Flow ◽  
Stokes Equations ◽  
Immersed Boundary ◽  
Critical Range ◽  
Flow Past ◽  
Boundary Method ◽  
Flow Past A Cylinder ◽  
Submerged Cylinder

In the present work, the oscillatory flow past a submerged cylinder near above a horizontal bed is simulated by a Navier-Stokes equations solver. The boundary conditions, i.e., the no-slip condition on solid boundaries are imposed with the immersed boundary method. A Cartesian grid with variable size is used for the spatial discretization, and a time-splitting scheme is used for the temporal discretization. The numerical method was validated simulating the unidirectional flow past a cylinder at Reynolds number ReD = 300. For the oscillatory flow past a cylinder of diameter D at a distance G above a horizontal bed, all variables were rendered dimensionless using the maximum velocity, Uo, and the amplitude of the orbital motion, αo, of the oscillatory flow. Several tests with differing values of αo/D and G/D were considered, for Reynolds number Reα = 5,000 and Keulegan–Carpenter numbers in the range from 6.28 to 62.8. Results show that the critical range for the suppression of vortex shedding at the lower side of the cylinder is G/αo<0.01, while the critical range for the generation of vorticity uplift from the bed boundary layer is G/αo<1.0. Also, as G/D decreases, both the amplitude of the drag force and the bias towards positive values of the lift force increase.

Numerical Investigation of Vortex Shedding Modes of Flow past Two Circular Cylinders in Side-by-Side Using Immersed Boundary Method

2013 ◽  
Vol 275-277 ◽  
pp. 482-485
Author(s):  
Li Wei Song ◽  
Song Ping Wu
Keyword(s):  
Vortex Shedding ◽  
Immersed Boundary Method ◽  
Stokes Equations ◽  
Circular Cylinders ◽  
Immersed Boundary ◽  
Step Method ◽  
Fractional Step Method ◽  
Flow Past ◽  
Boundary Method ◽  
Vortex Shedding Modes

The vortex shedding modes of flow past two circular cylinders in side-by-side arrangement are investigated numerically in this paper. The simulations are carried out using a ghost cell immersed boundary method which imposes the boundary condition through reconstruction of the local velocity field near the immersed boundary. The two-dimensional unsteady incompressible Navier-Stokes equations are solved using an implicit fractional step method based on cell-center, collocated arrangement of the primary variables. Vorticity contours of the flow around the cylinders and force time histories are presented. Anti-phase and in-phase vortex shedding modes were found to exist in the flow simulation. These results of simulations were in agreement with phenomena observed in experiment and numerical results of previous researchers.

scholarly journals A computational study of drag reduction and vortex shedding suppression of flow past a square cylinder in presence of small control cylinders

AIP Advances ◽  
2017 ◽  
Vol 7 (4) ◽  
pp. 045119 ◽  
Author(s):  
Shams-Ul. Islam ◽  
Raheela Manzoor ◽  
Zia-Ul. Islam ◽  
Shazia Kalsoom ◽  
Zhou Chao Ying
Keyword(s):  
Drag Reduction ◽  
Vortex Shedding ◽  
Computational Study ◽  
Square Cylinder ◽  
Flow Past

Uniform Flow Past a Rotary Oscillating Circular Cylinder

2011 ◽  
Author(s):  
Lue Derek Du ◽  
Charles Dalton
Keyword(s):  
Circular Cylinder ◽  
Vortex Shedding ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Uniform Flow ◽  
Resonance Phenomenon ◽  
Curvilinear Coordinates ◽  
Wake Structure ◽  
Flow Past ◽  
Wide Range

In this paper, we study uniform flow past a rotary oscillating circular cylinder computationally. The objective is to determine the effect the oscillating rotation has on the lift and drag forces acting on the cylinder, on the wake structure, and on vortex shedding. A combination of finite-difference and spectral methods is used to calculate the three-dimensional incompressible unsteady Navier-Stokes equations in primitive variable form in nonorthogonal curvilinear coordinates. Wake turbulence is modeled by an LES technique. The Reynolds number considered is Re = 1.5×104, which is the same as that in the experimental study of Tokumaru & Dimotakis (1991), who suggested this technique as a means of reducing drag. We fix the forcing amplitude at the moderate value of Ω = 2 and vary the forcing frequency in a wide range to study its effect on the flow. The resonance phenomenon and drag reduction effect are carefully examined. The wake structure and vortex shedding process is visualized by means of computational streaklines. These results have a practical application in offshore engineering.

scholarly journals An Explicit Meshless Point Collocation Solver for Incompressible Navier-Stokes Equations

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 164 ◽  
Author(s):  
Bourantas ◽  
Zwick ◽  
Joldes ◽  
Loukopoulos ◽  
Tavner ◽  
...  
Keyword(s):  
Stokes Equations ◽  
Two Dimensions ◽  
Navier Stokes ◽  
Benchmark Problems ◽  
Implicit Methods ◽  
Time Step ◽  
Flow Equations ◽  
Point Collocation ◽  
Flow Past ◽  
Flow Past A Cylinder

We present a strong form, meshless point collocation explicit solver for the numerical solution of the transient, incompressible, viscous Navier-Stokes (N-S) equations in two dimensions. We numerically solve the governing flow equations in their stream function-vorticity formulation. We use a uniform Cartesian embedded grid to represent the flow domain. We discretize the governing equations using the Meshless Point Collocation (MPC) method. We compute the spatial derivatives that appear in the governing flow equations, using a novel interpolation meshless scheme, the Discretization Corrected Particle Strength Exchange (DC PSE). We verify the accuracy of the numerical scheme for commonly used benchmark problems including lid-driven cavity flow, flow over a backward-facing step and unbounded flow past a cylinder. We have examined the applicability of the proposed scheme by considering flow cases with complex geometries, such as flow in a duct with cylindrical obstacles, flow in a bifurcated geometry, and flow past complex-shaped obstacles. Our method offers high accuracy and excellent computational efficiency as demonstrated by the verification examples, while maintaining a stable time step comparable to that used in unconditionally stable implicit methods. We estimate the stable time step using the Gershgorin circle theorem. The stable time step can be increased through the increase of the support domain of the weight function used in the DC PSE method.

Numerical Simulation of Three-Dimensional Flow Past a Cylinder Oscillating at the Strouhal Frequency

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
S. Peppa ◽  
L. Kaiktsis ◽  
G. S. Triantafyllou
Keyword(s):  
Numerical Simulation ◽  
Stokes Equations ◽  
Oscillation Amplitude ◽  
Three Dimensional ◽  
Spectral Element ◽  
Transverse Oscillation ◽  
3D Flow ◽  
Flow Past ◽  
Flow Past A Cylinder ◽  
Uniform Stream

The paper presents computational results of 3D flow past a cylinder forced to oscillate: (a) transversely with respect to a uniform stream and (b) both transversely and in-line with respect to a uniform stream, following a figure-eight trajectory. For a flow from left to right the figure-eight is traversed counterclockwise in the upper half-plane. Direct numerical simulation (DNS) of the Navier–Stokes equations for 3D flow is performed using a spectral element code. Computations are carried out for a Reynolds number equal to 400, at a transverse oscillation frequency equal to the natural frequency of the Kármán vortex street. For both oscillation modes, the transverse oscillation amplitude is varied from 0 to 0.60 cylinder diameters. The forces on the cylinder are calculated and related to flow structure in the wake. The results indicate that, in general, the presence of in-line oscillation increases the magnitude of forces acting on the cylinder, as well as the power transfer from the flow to the structure. Flow visualizations indicate that, for the figure-eight mode, low-amplitude forcing tends to reduce the wake three-dimensionality. However, at high oscillation amplitudes, the wake structure is found to become more complex at increasing amplitude.

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