Reduction of fluid forces acting on a single circular cylinder and two circular cylinders by using tripping rods

2003 ◽  
Vol 18 (3-4) ◽  
pp. 347-366 ◽  
Author(s):  
Md.Mahbub Alam ◽  
H Sakamoto ◽  
M Moriya
Keyword(s):  
Circular Cylinder ◽  
Circular Cylinders ◽  
Fluid Forces

Application of Models for Laminar to Turbulent Transition to Flow Around a Circular Cylinder

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
C. Reichel ◽  
K. Strohmeier
Keyword(s):  
Circular Cylinder ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Circular Cylinders ◽  
Spatial Direction ◽  
Number Range ◽  
Fluid Forces ◽  
Laminar To Turbulent Transition ◽  
Heat Exchanger Design ◽  
Turbulent Transition

In many technical fields, for example, in heat exchanger design, circular cylinders are involved in fluid structure interaction problems. Therefore, correct fluid forces are needed. Direct numerical simulation or large eddy simulation are too time expensive, but great errors can occur if fluid forces are evaluated with mainstream statistical turbulence models. In this paper, several models are applied to flow around a circular cylinder in the Reynolds number range from 500 up to 106. Mainly 2D simulations are performed. Additionally, calculations are performed to evaluate the influence of three dimensional modeling. The incorrect prediction of laminar to turbulent transition is identified as the main reason for the misprediction of flow forces with common statistical turbulence models. It is demonstrated that improvements are possible with available transition models. Although no grid independence in spatial direction could be achieved, the results indicate that 3D calculations may abolish remaining deviations between calculated and measured force coefficients. (Most of the data contained within this paper have been presented at the 2005 ASME PVPD Conference in Denver, Colorado. Although the title of the paper has not been changed, some newer results have been added.)

Application of Models for Laminar to Turbulent Transition to Flow Around a Circular Cylinder

2005 ◽  
Author(s):  
Christoph Reichel ◽  
Klaus Strohmeier
Keyword(s):  
Circular Cylinder ◽  
Lift Coefficient ◽  
Turbulence Models ◽  
Circular Cylinders ◽  
Number Range ◽  
Fluid Forces ◽  
Laminar To Turbulent Transition ◽  
Turbulent Transition ◽  
Transition Models ◽  
Transition Modeling

In many technical fields, for example heat exchangers, circular cylinders are involved in Fluid Structure Interaction (FSI) problems. Therefore correct fluid forces or Strouhal number, drag and fluctuating lift coefficient are needed. On one hand Direct Numerical Simulation (DNS) or Large Eddy Simulation (LES) are too time-expensive, on the other hand great errors can occur, if fluid forces are evaluated with mainstream statistical turbulence models. An incorrect prediction of laminar to turbulent transition and correspondingly a miscalculation of the separation point is the main reason. Several turbulence models and models for laminar to turbulent transition are applied to flow around a circular cylinder in the Reynolds number range from 500 up to 106. Mainly 2D simulations demonstrate the large improvements that are possible with transition models. Additionally calculations are presented to evaluate whether the class of statistical turbulence and transition models is influenced by three dimensional modeling. Results will be presented for the Shear Stress Transport (SST) and the Wilcox98 k-ω turbulence model. While the latter can be modified according to a proposal of Wilcox (1998) to take transition into account, the commercial code we use at our institute provides several extensions for transition modeling together with the SST model.

Steady approach of unsteady low-Reynolds-number flow past two rotating circular cylinders

2013 ◽  
Vol 736 ◽  
pp. 414-443 ◽  
Author(s):  
Y. Ueda ◽  
T. Kida ◽  
M. Iguchi
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Stokes Equations ◽  
Low Reynolds Number ◽  
Vortex Method ◽  
The Self ◽  
Circular Cylinders ◽  
Far Field ◽  
Flow Past ◽  
Low Reynolds

AbstractThe long-time viscous flow about two identical rotating circular cylinders in a side-by-side arrangement is investigated using an adaptive numerical scheme based on the vortex method. The Stokes solution of the steady flow about the two-cylinder cluster produces a uniform stream in the far field, which is the so-called Jeffery’s paradox. The present work first addresses the validation of the vortex method for a low-Reynolds-number computation. The unsteady flow past an abruptly started purely rotating circular cylinder is therefore computed and compared with an exact solution to the Navier–Stokes equations. The steady state is then found to be obtained for $t\gg 1$ with ${\mathit{Re}}_{\omega } {r}^{2} \ll t$, where the characteristic length and velocity are respectively normalized with the radius ${a}_{1} $ of the circular cylinder and the circumferential velocity ${\Omega }_{1} {a}_{1} $. Then, the influence of the Reynolds number ${\mathit{Re}}_{\omega } = { a}_{1}^{2} {\Omega }_{1} / \nu $ about the two-cylinder cluster is investigated in the range $0. 125\leqslant {\mathit{Re}}_{\omega } \leqslant 40$. The convection influence forms a pair of circulations (called self-induced closed streamlines) ahead of the cylinders to alter the symmetry of the streamline whereas the low-Reynolds-number computation (${\mathit{Re}}_{\omega } = 0. 125$) reaches the steady regime in a proper inner domain. The self-induced closed streamline is formed at far field due to the boundary condition being zero at infinity. When the two-cylinder cluster is immersed in a uniform flow, which is equivalent to Jeffery’s solution, the streamline behaves like excellent Jeffery’s flow at ${\mathit{Re}}_{\omega } = 1. 25$ (although the drag force is almost zero). On the other hand, the influence of the gap spacing between the cylinders is also investigated and it is shown that there are two kinds of flow regimes including Jeffery’s flow. At a proper distance from the cylinders, the self-induced far-field velocity, which is almost equivalent to Jeffery’s solution, is successfully observed in a two-cylinder arrangement.

Elasticity Solution for a Radially Nonhomogeneous Hollow Circular Cylinder

1999 ◽  
Vol 66 (3) ◽  
pp. 598-606 ◽  
Author(s):  
Xiangzhou Zhang ◽  
Norio Hasebe
Keyword(s):  
Circular Cylinder ◽  
Continuous Functions ◽  
Variable Coefficients ◽  
Circular Cylinders ◽  
Explicit Solutions ◽  
Elasticity Solution ◽  
First Order ◽  
Hollow Circular Cylinder ◽  
Homogeneous Elasticity ◽  
Ordinary Differential Equation Systems

An exact elasticity solution is developed for a radially nonhomogeneous hollow circular cylinder of exponential Young’s modulus and constant Poisson’s ratio. In the solution, the cylinder is first approximated by a piecewise homogeneous one, of the same overall dimension and composed of perfectly bonded constituent homogeneous hollow circular cylinders. For each of the constituent cylinders, the solution can be obtained from the theory of homogeneous elasticity in terms of several constants. In the limit case when the number of the constituent cylinders becomes unboundedly large and their thickness tends to infinitesimally small, the piecewise homogeneous hollow circular cylinder reverts to the original nonhomogeneous one, and the constants contained in the solutions for the constituent cylinders turn into continuous functions. These functions, governed by some systems of first-order ordinary differential equations with variable coefficients, stand for the exact elasticity solution of the nonhomogeneous cylinder. Rigorous and explicit solutions are worked out for the ordinary differential equation systems, and used to generate a number of numerical results. It is indicated in the discussion that the developed method can also be applied to hollow circular cylinders with arbitrary, continuous radial nonhomogeneity.

A Model for High-Reynolds-Number Flow Past Rough-Walled Circular Cylinders

1977 ◽  
Vol 99 (3) ◽  
pp. 486-493 ◽  
Author(s):  
O. Gu¨ven ◽  
V. C. Patel ◽  
C. Farell
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Circular Cylinder ◽  
Turbulent Boundary Layer ◽  
Pressure Coefficient ◽  
Empirical Relation ◽  
Reynolds Numbers ◽  
Boundary Layer Separation ◽  
Circular Cylinders ◽  
Mean Flow

A simple analytical model for two-dimensional mean flow at very large Reynolds numbers around a circular cylinder with distributed roughness is presented and the results of the theory are compared with experiment. The theory uses the wake-source potential-flow model of Parkinson and Jandali together with an extension to the case of rough-walled circular cylinders of the Stratford-Townsend theory for turbulent boundary-layer separation. In addition, a semi-empirical relation between the base-pressure coefficient and the location of separation is used. Calculation of the boundary-layer development, needed as part of the theory, is accomplished using an integral method, taking into account the influence of surface roughness on the laminar boundary layer and transition as well as on the turbulent boundary layer. Good agreement with experiment is shown by the results of the theory. The significant effects of surface roughness on the mean-pressure distribution on a circular cylinder at large Reynolds numbers and the physical mechanisms giving rise to these effects are demonstrated by the model.

scholarly journals The Investigation of Mutual Interference Vortex Flow around Two Circular Cylinders by Flow Visualization and Pressure Measurement

2019 ◽  
Vol 291 ◽  
pp. 02001
Author(s):  
Yoshifumi Yokoi ◽  
Rut Vitkovičová
Keyword(s):  
Circular Cylinder ◽  
Pressure Measurement ◽  
Pressure Coefficient ◽  
Visual Observation ◽  
Mutual Interference ◽  
Circular Cylinders ◽  
Cylinder Surface ◽  
Visualization Experiment ◽  
Flow Apparatus ◽  
Measurement Experiment

In order to understand the aspect of the mutual interference flow from two circular cylinders, the visual observation experiment and the pressure measurement experiment were performed by use a water flow apparatus. Two circular cylinders with a diameter of D=10mm were used, and they have been arranged at staggered or tandem. The flow velocity was U=0.25m/s (Re=UD/í, í is kinematic viscosity of fluid). The dye oozing streak method was used in the visualization experiment. In the pressure measurement experiment, the pressure on the surface of a circular cylinder was detected by the single tube manometer, and measurement was performed by image processing using a computer. As a result, distribution of the circular cylinder surface pressure coefficient CP corresponding to the flow pattern and it in each circular cylinder arrangement was obtained. The drag coefficient CD was calculated from the pressure coefficient CP, and change of the resistance in each arrangement was found.

Circular Cylinder Exposed to Cross Flow Fluid Forces – Parameters of Influence – Limits of Numerical Models

2003 ◽  
Author(s):  
Christoph Reichel ◽  
Klaus Strohmeier
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Models ◽  
Lift Coefficient ◽  
Cross Flow ◽  
Circular Cylinders ◽  
Rigid Cylinder ◽  
Fluid Forces ◽  
Wide Range ◽  
Dynamics Simulations

In many technical fields, e.g. heat exchangers, circular cylinders are involved in Fluid Structure Interaction (FSI) problems. Therefore correct frequency and magnitude of fluid forces, respectively Strouhal number, drag and lift coefficient are needed. If fluid forces are evaluated with Computational Fluid Dynamics (CFD), mostly flow around a rigid cylinder is used to verify model and numerical methods. Unfortunately experimental as well as numerical results show great variation, making verification and testing of models difficult. Reynolds number is regarded as main influencing parameter for a rigid cylinder in cross flow. Most of experimental deviations can be related to other parameters, which differ from experiment to experiment. In this paper such parameters are specified and it is shown, that a closer look is needed, if one really wants to verify a model. Besides experimental results, which can be found in literature, some parameters are investigated by numerical simulation. Like experiments CFD (Computational Fluid Dynamics) simulations show a huge bandwidth of results, even when the same turbulence model is used. Flow around cylinders separates over a wide range of Reynolds numbers. It will be demonstrated that, using CFD, large deviations in fluid forces can often be related to miscalculation of the point of separation.

The Hydrodynamic Forces Acting on a Long Flexible Circular Cylinder Responding to VIV

2006 ◽  
Author(s):  
P. W. Bearman ◽  
F. J. Huera Huarte ◽  
J. R. Chaplin
Keyword(s):  
Circular Cylinder ◽  
Cross Flow ◽  
Element Model ◽  
Transverse Force ◽  
Diameter Ratio ◽  
Mass Ratio ◽  
Force Coefficients ◽  
Fluid Forces ◽  
Maximum Value ◽  
Vibration Prediction

Distributions of the fluid forces acting along a long flexible circular cylinder free to respond in-line and transverse to a stepped current are presented. Forces are calculated using a finite element model of the cylinder with measured responses providing the input. The length to diameter ratio of the model used was 469, the mass ratio was 3 and the Reynolds number could be varied up to maximum value of approximately 2.6 · 104. Fluid force coefficients for two cases are presented: in the first, the dominant modes are the 2nd cross-flow and the 4th in line. For the second case the leading modes are the 7th and 12th respectively. In general, transverse force coefficients and in-line drag coefficients are found to be larger than those measured for short sections of cylinder undergoing free and forced one and two-dimensional motions. It is anticipated that the results will be of value to developers of vortex-induced vibration prediction methods.

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