Numerical Simulation of Flow over a Circular Cylinder at Low Reynolds Number

2011 ◽  
Vol 255-260 ◽  
pp. 942-946
Author(s):  
Hua Bai ◽  
Jia Wu Li
Keyword(s):  
Numerical Simulation ◽  
Circular Cylinder ◽  
Vortex Shedding ◽  
Medial Axis ◽  
Lift Coefficient ◽  
Cross Flow ◽  
Reynolds Numbers ◽  
Control Measures ◽  
Hydrodynamic Characteristics ◽  
Two Dimensional

The hydrodynamic characteristics of a circular cylinder in two-dimensional unsteady uniform cross flow was simulated numerically by the laminar model with the reasonable mesh used the method of fluent. The focus of this numerical simulation was to research the characteristics of pressure distribution, drag coefficient and lift coefficient, and the Strouhal number was calculated at Reynolds-numbers value of 200. The results agree well with experimental data and other numerical results according to the reference. In order to study the control measures of the flow over a circular cylinder, the different baffles inserted at various locations downstream of the cylinder have been compared. The results shows that the vortex shedding of flow over a circular cylinder could be well controlled by place the baffle at a right position of the downstream medial axis of the cylinder, which could reduce drag and resist vibration.

Numerical Simulation of Vortex Shedding From a Circular Cylinder in the Presence of a Free Surface

2003 ◽  
Author(s):  
S. Nagaya ◽  
R. E. Baddour
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Free Surface ◽  
Circular Cylinder ◽  
Vortex Shedding ◽  
Fluid Flows ◽  
Reynolds Numbers ◽  
Cfd Simulations ◽  
Induced Drag

CFD simulations of crossflows around a 2-D circular cylinder and the resulting vortex shedding from the cylinder are conducted in the present study. The capability of the CFD solver for vortex shedding simulation from a circular cylinder is validated in terms of the induced drag and lifting forces and associated Strouhal numbers computations. The validations are done for uniform horizontal fluid flows at various Reynolds numbers in the range 103 to 5×105. Crossflows around the circular cylinder beneath a free surface are also simulated in order to investigate the characteristics of the interaction between vortex shedding and a free surface at Reynolds number 5×105. The influence of the presence of the free surface on the vortex shedding due to the cylinder is discussed.

Numerical Simulation of Vortex Shedding Past a Circular Cylinder in a Cross-Flow at Low Reynolds Number With Finite Volume-Technique: Part 1 — Forced Oscillations

2007 ◽  
Author(s):  
Antoine Placzek ◽  
Jean-Franc¸ois Sigrist ◽  
Aziz Hamdouni
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Circular Cylinder ◽  
Finite Volume ◽  
Vortex Shedding ◽  
Stokes Equations ◽  
Cross Flow ◽  
Forced Oscillations ◽  
Lift And Drag ◽  
Wake Characteristics

The numerical simulation of the flow past a circular cylinder forced to oscillate transversely to the incident stream is presented here for a fixed Reynolds number equal to 100. The 2D Navier-Stokes equations are solved with a classical Finite Volume Method with an industrial CFD code which has been coupled with a user subroutine to obtain an explicit staggered procedure providing the cylinder displacement. A preliminary work is conducted in order to check the computation of the wake characteristics for Reynolds numbers smaller than 150. The Strouhal frequency fS, the lift and drag coefficients CL and CD are thus controlled among other parameters. The simulations are then performed with forced oscillations f0 for different frequency rations F = f0/fS in [0.50–1.50] and an amplitude A varying between 0.25 and 1.25. The wake characteristics are analysed using the time series of the fluctuating aerodynamic coefficients and their FFT. The frequency content is then linked to the shape of the phase portrait and to the vortex shedding mode. By choosing interesting couples (A,F), different vortex shedding modes have been observed, which are similar to those of the Williamson-Roshko map.

A Numerical Simulation of Vortex Induced Vibration on a Elastically Supported Circular Rigid Cylinder at Moderate Reynolds Numbers

2008 ◽  
Author(s):  
Jean-Franc¸ois Sigrist ◽  
Cyrille Allery ◽  
Claudine Beghein
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Circular Cylinder ◽  
Finite Volume ◽  
Vortex Shedding ◽  
Numerical Study ◽  
Reynolds Numbers ◽  
Forced Oscillations ◽  
Vortex Induced Vibration ◽  
Elastically Supported

The present paper is the sequel of a previously published study which is concerned with the numerical simulation of vortex-induced-vibration (VIV) on an elastically supported rigid circular cylinder in a fluid cross-flow (A. Placzek, J.F. Sigrist, A. Hamdouni; Numerical Simulation of Vortex Shedding Past a Circular Cylinder at Low Reynolds Number with Finite Volume Technique. Part I: Forced Oscillations, Part II: Flow Induced Vibrations; Pressure Vessel and Piping, San Antonio, 22–26 July 2007). Such a problem has been thoroughly studied over the past years, both from the experimental and numerical points of view, because of its theoretical and practical interest in the understanding on flow-induced vibration problems. In this context, the present paper aims at exposing a numerical study based on a fully coupled fluid-structure simulation. The numerical technique is based on a finite volume discretisation of the fluid flow equations together with i) a re-meshing algorithm to account for the cylinder motion ii) a projection subroutine to compute the forces induced by the fluid on the cylinder and iii) a coupling procedure to describe the energy exchanges between the fluid flow and solid motion. The study is restricted to moderate Reynolds numbers (Re∼2.000–10.000) and is performed with an industrial CFD code. Numerical results are compared with existing literature on the subject, both in terms of cylinder amplitude motion and fluid vortex shedding modes. Ongoing numerical studies with different numerical techniques, such as ROM (Reduced Order Models)-based methods, will complete the approach and will be published in next PVP conference. These numerical simulations are proposed for code validation purposes prior to industrial applications in tube bundle configuration.

Computational Determination of the Modified Vortex Shedding Frequency for a Rigid, Truncated, Wall-Mounted Cylinder in Cross Flow

2014 ◽  
Author(s):  
Aimie Faucett ◽  
Todd Harman ◽  
Tim Ameel
Keyword(s):  
Vortex Shedding ◽  
Cross Flow ◽  
Classical Case ◽  
Reynolds Numbers ◽  
Two Dimensional ◽  
End Effects ◽  
Dimensional Solution ◽  
Horseshoe Vortices ◽  
Vortex Shedding Frequency ◽  
Shedding Frequency

Flow around a rigid, truncated, wall-mounted cylinder with an aspect ratio of 5 is examined computationally at various Reynolds numbers Re to determine how the end effects impact the vortex shedding frequency. The existence of the wall and free end cause a dampening of the classical shedding frequency found for a semi-infinite, two-dimensional cylinder, as horseshoe vortices along the wall and flow over the tip entrain into the shedding region. This effect was observed for Reynolds numbers in the range of 50 to 2000, and quantified by comparing the modified Strouhal numbers to the classical (two-dimensional) solution for Strouhal number as a function of Reynolds number. The range of transition was found to be 220 < Re < 300, versus 150 < Re < 300 for the classical case. Vortex shedding started at Re ≈ 100, significantly above Re = 50, where shedding starts for the two-dimensional case.

Synchronized Vibrations of a Circular Cylinder in Cross Flow at Supercritical Reynolds Numbers1

2003 ◽  
Vol 125 (1) ◽  
pp. 97-108 ◽  
Author(s):  
Tsutomu Kawamura ◽  
Toshitsugu Nakao ◽  
Masanori Takahashi ◽  
Masaaki Hayashi ◽  
Kouichi Murayama ◽  
...  
Keyword(s):  
Circular Cylinder ◽  
Strouhal Number ◽  
Vortex Shedding ◽  
Cross Flow ◽  
Reynolds Numbers ◽  
Excited Vibration ◽  
Karman Vortex ◽  
Lock In

Synchronized vibrations of a circular cylinder in a water cross flow at supercritical Reynolds numbers were measured. Turbulence intensities were varied to investigate the effect of the Strouhal number on the synchronization range. Self-excited vibration in the drag direction due to symmetrical vortex shedding began only when the Strouhal number was about 0.29, at a reduced velocity of 1.1. The reduced velocities at the beginning of lock-in vibrations caused by Karman vortex shedding decreased from 1.5 to 1.1 in the drag direction and from 2.7 to 2.2 in the lift direction, as the Strouhal number increased from 0.29 to 0.48.

Influence of Thermal Buoyancy on Vortex Shedding Behind a Rotating Circular Cylinder in Cross Flow at Subcritical Reynolds Numbers

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Dipankar Chatterjee ◽  
Chiranjit Sinha
Keyword(s):  
Circular Cylinder ◽  
Vortex Shedding ◽  
Thermal Instability ◽  
Cross Flow ◽  
Reynolds Numbers ◽  
Forced Flow ◽  
Thermal Buoyancy ◽  
Thermal Fields ◽  
Rotating Circular Cylinder ◽  
Unbounded Medium

The vortex shedding (VS) behind stationary bluff obstacles in cross-flow can be initiated by imposing thermal instability at subcritical Reynolds numbers (Re). We demonstrate here that additional thermal instability is required to be imparted in the form of heating for destabilizing the flow around a rotating bluff obstacle. A two-dimensional numerical simulation is performed in this regard to investigate the influences of cross buoyancy on the VS process behind a heated and rotating circular cylinder at subcritical Re. The flow is considered in an unbounded medium. The range of Re is chosen to be 5–45 with a dimensionless rotational speed (Ω) ranging between 0 and 4. At this subcritical range of Reynolds number the flow and thermal fields are found to be steady without the superimposed thermal buoyancy (i.e., for pure forced flow). However, as the buoyancy parameter (Richardson number, Ri) increases flow becomes unstable and subsequently, at some critical value of Ri, periodic VS is observed to characterize the flow and thermal fields. The rotation of the cylinder is found to have a stabilizing effect and as Ω increases more heating is observed to be required to destabilize the flow.

Effect of Inclination Angle of Splitter Plate on Flow Over a Circular Cylinder

2011 ◽  
Author(s):  
Li Zhang ◽  
Lin Ding
Keyword(s):  
Circular Cylinder ◽  
Strouhal Number ◽  
Inclination Angle ◽  
Vortex Shedding ◽  
Lift Coefficient ◽  
Reynolds Numbers ◽  
Splitter Plate ◽  
Plate Length ◽  
Pressure Distributions ◽  
Vortex Shedding Frequency

Two-dimensional unsteady laminar flow over a circular cylinder with an attached splitter plate was investigated numerically. To see the effect of the splitter plate length and inclination angle on the pressure distributions and vortex shedding, numerical simulations were done for moderate Reynolds numbers ranging from 100 to 500 in two different splitter plate lengths (1 and 2 diameters), and the angles between splitter plate and wake centerline was changed from 0 to 45 deg. Results indicate that the wake structure and length are dependent on the inclination angle of splitter plate. Near wake length is almost unchanged when θ>25 deg. On the other hand, circular cylinder’s drag coefficient is distinctly affected by the position of vortex. And significant local peaks of the RMS lift coefficient are obtained at θ=15 deg and 5 deg for L=1D and 2D respectively. The lift force is in one direction when the inclination angle is over a critical value. In addition, the non-dimensional Strouhal number representing the vortex shedding frequency characteristics varies as a function of the angle and has peak values at θ=20 and 5 deg for L=1D and 2D respectively. And the longer splitter plate causes more decrease in the Strouhal number for θ>15 deg.

Two-Dimensional Numerical Simulation of Vortex Shedding of Multiple Stranded Ropes

2019 ◽  
Author(s):  
Xinxin Wang ◽  
Liuyi Huang ◽  
Yanli Tang ◽  
Fenfang Zhao ◽  
Peng Sun
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Vortex Shedding ◽  
Stokes Equations ◽  
Flow Distribution ◽  
Hydrodynamic Performance ◽  
Navier Stokes ◽  
Hydrodynamic Characteristics ◽  
Two Dimensional ◽  
Navier Stokes Equation

Abstract The stranded rope is one of the important components of the fishery aquaculture equipment. We investigate the fluid flow through two-dimensional stranded rope by direct simulation of the Navier-Stokes equations. We show that for different kinds of stranded rope structures, there are significant differences in hydrodynamic performance. This paper established a numerical model of unsteady flow past the stranded rope based on the Navier-Stokes equation and Morison formulas to study the hydrodynamic characteristics of three-stranded rope, four-stranded rope, and seven-stranded rope, respectively. The turbulence flow was simulated using Standard k-ε model and Shear-Stress Transport k-ω (SST) model. The flow distribution strongly depends on the Reynolds number, a range of 3,900 and 30,000. With increasing Reynolds number, the alternate eddy formation and shedding were repeated behind the stranded ropes. Such parameters of hydrodynamic characteristics of multiple stranded ropes were calculated as the lift and drag coefficients, and vortex shedding frequencies. The numerical simulation results presented flow performances of different cross sections (a, b, c, d) at different Reynolds numbers. However, Reynolds number has no significant impact on the Strouhal number for the same attack angle of the stranded rope.

scholarly journals Vortex Shedding Characteristics from a Stationary Circular Cylinder in Cross Flow at Supercritical Reynolds Numbers.

1999 ◽  
Vol 65 (635) ◽  
pp. 2212-2220
Author(s):  
Tsutomu KAWAMURA ◽  
Toshitsugu NAKAO ◽  
Masanori TAKAHASHI ◽  
Masaaki HAYASHI ◽  
Kouichi MURAYAMA
Keyword(s):  
Circular Cylinder ◽  
Vortex Shedding ◽  
Cross Flow ◽  
Reynolds Numbers
Sign in / Sign up

Export Citation Format

Share Document