Interaction of a Steady Approach Flow and a Circular Cylinder Undergoing Forced Oscillation

1997 ◽  
Vol 119 (4) ◽  
pp. 808-813 ◽  
Author(s):  
Jianfeng Zhang ◽  
Charles Dalton
Keyword(s):  
Circular Cylinder ◽  
Vortex Shedding ◽  
Stokes Equations ◽  
Numerical Study ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Large Eddy Simulation Model ◽  
Drag And Lift Coefficients ◽  
Eddy Simulation ◽  
Drag And Lift

This paper presents a numerical study on the interaction of a steady approach flow and the forced transverse oscillation of a circular cylinder. The two-dimensional stream-function/vorticity formulation of the Navier-Stokes equations is solved by a semi-implicit finite-difference scheme. Calculations for flows with different amplitude (a) and frequency (fc) of the oscillation of the cylinder show a strong effect of the oscillation when fc is close to fso, the vortex shedding frequency, of the stationary cylinder. Lock-on of vortex shedding, distinct flow patterns, and increase in both drag and lift coefficients from those of a stationary cylinder are observed for Reynolds number Re = 200, a/R (R is the radius of the cylinder) from 1.0 to 2.0, fc/fso from 0.85 to 1.7. For Re = 855, a/R = 0.26, a large eddy simulation model for turbulent flow is used. The results at Re = 855 and a/R = 0.26 show that lock-on has occurred for fc/fso ≥ 0.85. The behavior of the drag and lift coefficients is seen to be influenced by the lock-on phenomenon.

scholarly journals Some Modelling Issues on Trailing Edge Vortex Shedding

1999 ◽  
Author(s):  
Wei Ning ◽  
Li He
Keyword(s):  
Circular Cylinder ◽  
Vortex Shedding ◽  
Stokes Equations ◽  
Numerical Study ◽  
Independent Solution ◽  
Navier Stokes ◽  
Trailing Edge ◽  
Navier Stokes Equations ◽  
Averaged Equations ◽  
Edge Vortex

A numerical study has been carried out to investigate modelling issues on trailing edge vortex shedding. The vortex shedding from a circular cylinder and a VKI turbine blade is calculated using a 2-D unsteady multi-block Navier-Stokes solver. The unsteady stresses are calculated from the unsteady solutions. The distributions of the unsteady stresses are analysed and compared for the cylinder case and the cascade case, respectively. The time-averaged equations are then solved and the effectiveness of the “unsteady stresses” in suppressing trailing edge vortex shedding is checked. Finally, the time-independent solution produced by solving the time-averaged equations is compared with the time-averaged solution obtained by integrating the unsteady solutions. The numerical results have demonstrated that a time-independent vortex shedding solution can be achieved by solving the Navier-Stokes equations with the unsteady stresses and the time-averaged effects of the vortex shedding can be included.

CFD Analysis of Vortex Shedding in a Circular Cylinder: Flow Induced Vibration Design

2006 ◽  
Author(s):  
Nadeem Ahmed Sheikh ◽  
M. Afzaal Malik ◽  
Arshad Hussain Qureshi ◽  
M. Anwar Khan ◽  
Shahab Khushnood
Keyword(s):  
Circular Cylinder ◽  
Vortex Shedding ◽  
Stokes Equations ◽  
Boundary Layer Separation ◽  
The Body ◽  
Navier Stokes ◽  
Structural Vibrations ◽  
Flow Induced Vibration ◽  
Navier Stokes Equations ◽  
Implicit Approach

Flow past a blunt body, such as a circular cylinder, usually experiences boundary layer separation and very strong flow oscillations in the wake region behind the body at a discrete frequency that is correlated to the Reynolds number of the flow. The periodic nature of the vortex shedding phenomenon can sometimes lead to unwanted structural vibrations. The effect of vibrating instability of a single cylinder is investigated in a uniform flow using the power of computational methods. Fluid structure coupling procedure predicts the fluid forces responsible for structural vibrations. An implicit approach to the solution of the unsteady two-dimensional Navier-Stokes equations is used for computation of flow parameters. Calculations are performed in parallel using a domain re-meshing/deforming technique with efficient communication requirements. Results for the unsteady shedding flow behind a circular cylinder are presented with experimental comparisons, showing the feasibility of accurate, efficient, time-dependent estimation of shedding frequency and resulting vibrations.

Large Eddy Simulation of Flow Past Circular Cylinder Based on the Least Square Meshless Method

2013 ◽  
Vol 394 ◽  
pp. 128-133
Author(s):  
Yuan Ding Wang ◽  
Jun Jie Tan ◽  
Xiao Wei Cai ◽  
Deng Feng Ren
Keyword(s):  
Circular Cylinder ◽  
Large Eddy Simulation ◽  
Meshless Method ◽  
Stokes Equations ◽  
Least Square ◽  
Scale Model ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Eddy Simulation ◽  
Large Eddy

Large Eddy Simulation (LES) based on the least square meshless method was proposed in the present paper to simulate the classical turbulent flow around a stationary 2D circular cylinder. The subgrid scale model of Smagorinsky-Lily was employed to close the Navier-Stokes equations filtered by Favre filter. The Reynolds number is 3900 which means that the flow is subcritical and the wake is fully turbulent but the cylinder boundary is still laminar. Results obtained in this paper were evaluated by comparison with published experimental results and other numerical results. The results obtained in the present work show better agreement with the experimental values than other two-dimensional LES results .

A numerical study of vortex shedding from flat plates with square leading and trailing edges

1992 ◽  
Vol 236 ◽  
pp. 445-460 ◽  
Author(s):  
Yuji Ohya ◽  
Yasuharu Nakamura ◽  
Shigehira Ozono ◽  
Hideki Tsuruta ◽  
Ryuzo Nakayama
Keyword(s):  
Shear Layer ◽  
Vortex Shedding ◽  
Stokes Equations ◽  
Numerical Study ◽  
Vortical Flow ◽  
Navier Stokes ◽  
Shear Layer Instability ◽  
Flat Plates ◽  
Navier Stokes Equations ◽  
Trailing Edges

This paper describes a numerical study of the flow around flat plates with square leading and trailing edges on the basis of a finite-difference analysis of the two-dimensional Navier—Stokes equations. The chord-to-thickness ratio of a plate, d/h, ranges from 3 to 9 and the value of the Reynolds number based on the plate's thickness is constant and equal to 103. The numerical computation confirms the finding obtained in our previous experiments that vortex shedding from flat plates with square leading and trailing edges is caused by the impinging-shear-layer instability. In particular, the Strouhal number based on the plate's chord increases stepwise with increasing d/h in agreement with the experiment. Numerical analyses also provide some crucial information on the complicated vortical flow occurring near the trailing edge in conjunction with the vortex shedding mechanism. Finally, the mechanism of the impinging-shear-layer instability is discussed in the light of the experimental and numerical findings.

A Numerical Study of Vortex Shedding From a Square Cylinder With Ground Effect

1997 ◽  
Vol 119 (3) ◽  
pp. 512-518 ◽  
Author(s):  
Robert R. Hwang ◽  
Chia-Chi Yao
Keyword(s):  
Vortex Shedding ◽  
Stokes Equations ◽  
Numerical Study ◽  
Subsequent Development ◽  
Ground Effect ◽  
Navier Stokes ◽  
Square Cylinder ◽  
Navier Stokes Equations ◽  
Layer Flow ◽  
Volume Method

A numerical study has been conducted to investigate the behavior of the vortical wake created by a square cylinder placed in a laminar boundary-layer flow. The calculations are performed by solving the unsteady 2D Navier-Stokes equations with a finite-volume method. The Reynolds-number regime investigated is from 500 to 1500. Another parameter that is varied is the distance of the cylinder from the wall. The initial and subsequent development of the vortex shedding phenomenon are investigated. The presence of the wall is found to have strong effects on the properties of these vortices, as well as lift, drag, and Strouhal number.

Vortex Shedding From a Square Cylinder With Ground Effect

2003 ◽  
Author(s):  
S. Bhattacharyya ◽  
D. K. Maiti
Keyword(s):  
Reynolds Number ◽  
Vortex Shedding ◽  
Stokes Equations ◽  
Numerical Study ◽  
Ground Effect ◽  
Staggered Grid ◽  
Navier Stokes ◽  
Square Cylinder ◽  
Navier Stokes Equations ◽  
Cylinder Length

Numerical study on the wake behind a square cylinder placed parallel to a wall has been made. Flow has been investigated in the laminar Reynolds number (based on the cylinder length) range. We have studied the flow field for different values of the non-dimensional gap length between cylinder and the wall. The case when the cylinder is placed on the wall has also been considered. The governing unsteady Navier-Stokes equations are discretised through the finite volume method on staggered grid system. A SIMPLER type of algorithm has been used to compute the discretised equations iteratively. Vortex shedding has been found to be influenced by the wall. Vortex shedding suppression occurs beyond a critical value of the gap length. Due to the shear, the drag experienced by the cylinder is found to increase with the reduction of gap length. The flow is found to be steady when the cylinder is placed on the wall at a range of Reynolds number.

scholarly journals Secondary frequencies in the wake of a circular cylinder with vortex shedding

1991 ◽  
Vol 225 ◽  
pp. 557-574 ◽  
Author(s):  
Saul S. Abarbanel ◽  
Wai Sun Don ◽  
David Gottlieb ◽  
David H. Rudy ◽  
James C. Townsend
Keyword(s):  
Circular Cylinder ◽  
Boundary Conditions ◽  
Stokes Equations ◽  
Numerical Study ◽  
Numerical Algorithms ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Low Reynolds Numbers ◽  
Two Dimensional Flow

A detailed numerical study of two-dimensional flow past a circular cylinder at moderately low Reynolds numbers has been conducted using three different numerical algorithms for solving the time-dependent compressible Navier–Stokes equations. It was found that if the algorithm and associated boundary conditions were consistent and stable, then the major features of the unsteady wake were well predicted. However, it was also found that even stable and consistent boundary conditions could introduce additional periodic phenomena reminiscent of the type seen in previous wind-tunnel experiments. However, these additional frequencies were eliminated by formulating the boundary conditions in terms of the characteristic variables. An analysis based on a simplified model provides an explanation for this behaviour.

scholarly journals The 3D Numerical Study on Flow and Sediment Properties of a River with Grouped Spur Dikes

2018 ◽  
Vol 40 ◽  
pp. 05056 ◽  
Author(s):  
Xun Han ◽  
Pengzhi Lin ◽  
Gary Parker
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Flume Experiments ◽  
Navier Stokes Equations ◽  
Sediment Properties ◽  
Eddy Simulation ◽  
Flow Motion ◽  
Spur Dikes

A 3D numerical model named NEWTANK is employed to investigate the flow motion and sediment transport in grouped spur dikes system. This model is based on the Navier-Stokes equations, adopting the Volume of Fluid (VOF) method to track the free surface motion, while the solid is described by using the Porous Media Method (PMM). The Large Eddy Simulation (LES) is applied to capture turbulence. In sediment calculation parts, the suspended load and bedload are treated separately but combined together to update bed variation eventually. The finite difference form and Two-step Projection Method are employed in the process of discretizing the governing equation. Several carefully selected flume experiments are introduced to verify this model's reliability before its application on the simulation of grouped spur dike case, and detailed flow characteristics and sediment properties are analyzed afterwards.

Three-Dimensional Numerical Study on the Interaction Between Dam-Break Wave and Cylinder Array

2018 ◽  
Vol 12 (02) ◽  
pp. 1840007 ◽  
Author(s):  
Tso-Ren Wu ◽  
Thi-Hong-Nhi Vuong ◽  
Jun-Wei Lin ◽  
Chia-Ren Chu ◽  
Chung-Yue Wang
Keyword(s):  
Energy Dissipation ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Eddy Simulation ◽  
Velocity Magnitude ◽  
Cylinder Array ◽  
Large Eddy

Energy dissipation mechamism is the key to study tsunami hazard mitigation. Numerical method is adopted to study the interaction between bores and square cylinders. The model solves the three-dimensional Navier–Stokes equations with Large-Eddy Simulation turbulence model. The Volume-of-fluid (VOF) method is used to track the complex free surface. We focus the investigation on the effect of cylinder height on the flow field. The results show that the turbulence diffusion is the main mechanism for energy dissipation. The flow patterns are significantly different within and beyond the cylinder array. The taller cylinders cause smaller velocity magnitude in the downstream area. In addition, a larger value of velocity magnitude and vorticity near the bottom is identified in the tall-cylinder case. These unique featuers make different dissipation rates.

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