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.

Beating of a circular cylinder mounted as an inverted pendulum

2008 ◽  
Vol 610 ◽  
pp. 217-247 ◽  
Author(s):  
A. VOORHEES ◽  
P. DONG ◽  
P. ATSAVAPRANEE ◽  
H. BENAROYA ◽  
T. WEI
Keyword(s):  
Circular Cylinder ◽  
Vortex Shedding ◽  
Inverted Pendulum ◽  
Three Dimensional ◽  
Detailed Examination ◽  
Circular Cylinders ◽  
Response Analysis ◽  
Amplitude Response ◽  
Number Range ◽  
Spatially Resolved

This paper contains temporally and spatially resolved flow visualization and DPIV measurements characterizing the frequency–amplitude response and three-dimensional vortex structure of a circular cylinder mounted like an inverted pendulum. Two circular cylinders were examined in this investigation. Both were 2.54 cm in diameter and ~140 cm long with low mass ratios, m* = 0.65 and 1.90, and mass–damping ratios, m*ζ = 0.038 and 0.103, respectively. Frequency–amplitude response analysis was done with the lighter cylinder while detailed wake structure visualization and measurements were done using the slightly higher-mass-ratio cylinder. Experiments were conducted over the Reynolds number range 1900≤Re≤6800 corresponding to a reduced velocity range of 3.7 ≤ U* ≤ 9.6. Detailed examination of the upper branch of the synchronization regime permitted, for the first time, the identification of short-time deviations in cylinder oscillation and vortex-shedding frequencies that give rise to beating behaviour. That is, while long-time averages of cylinder oscillation and vortex-shedding frequencies are identical, i.e. synchronized, it is shown that there is a slight mismatch between these frequencies over much shorter periods when the cylinder exhibits quasi-periodic beating. Data are also presented which show that vortex strength is also modulated from one cylinder oscillation to the next. Physical arguments are presented to explain both the origins of beating as well as why the quasi-periodicity of the beating envelopes becomes irregular; it is believed that this result may be generalized to a broader class of fluid–structure interactions. In addition, observations of strong vertical flows associated with the Kármán vortices developing 2–3 diameters downstream of the cylinder are presented. It is hypothesized that these three-dimensionalities result from both the inverted pendulum motion as well as free-surface effects.

On the Effects of Turbulence Modeling on the Fluid-Structure Interaction of a Rigid Cylinder

2016 ◽  
Author(s):  
Guilherme Feitosa Rosetti ◽  
Guilherme Vaz ◽  
André Luís Condino Fujarra
Keyword(s):  
Turbulence Modeling ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Boundary Layer Separation ◽  
Turbulent Transition ◽  
Moving Cylinder ◽  
Wide Range ◽  
Cylinder Flow ◽  
Laminar Turbulent Transition

The cylinder flow is a canonical problem for Computational Fluid Dynamics (CFD), as it can display several of the most relevant issues for a wide class of flows, such as boundary layer separation, vortex shedding, flow instabilities, laminar-turbulent transition and others. Several applications also display these features justifying the amount of energy invested in studying this problem in a wide range of Reynolds numbers. The Unsteady Reynolds Averaged Navier Stokes (URANS) equations combined with simplifying assumptions for turbulence have been shown inappropriate for the captive cylinder flow in an important range of Reynolds numbers. For that reason, recent improvements in turbulence modeling has been one of the most important lines of research within that issue, aiming at better prediction of flow and loads, mainly targeting the three-dimensional effects and laminar-turbulent transition, which are so important for blunt bodies. In contrast, a much smaller amount of work is observed concerning the investigation of turbulent effects when the cylinder moves with driven or free motions. Evidently, larger understanding of the contribution of turbulence in those situations can lead to more precise mathematical and numerical modeling of the flow around a moving cylinder. In this paper, we present CFD calculations in a range of moderate Reynolds numbers with different turbulence models and considering a cylinder in captive condition, in driven and in free motions. The results corroborate an intuitive notion that the inertial effects indeed play very important role in determining loads and motions. The flow also seems to adapt to the motions in such a way that vortices are more correlated and less influenced by turbulence effects. Due to good comparison of the numerical and experimental results for the moving-cylinder cases, it is observed that the choice of turbulence model for driven and free motions calculations is markedly less decisive than for the captive cylinder case.

Three-dimensional wakes behind cylinders of square and circular cross-section: early and long-time dynamics

2019 ◽  
Vol 870 ◽  
pp. 419-432 ◽  
Author(s):  
G. Agbaglah ◽  
C. Mavriplis
Keyword(s):  
Circular Cylinder ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Early Time ◽  
Reynolds Numbers ◽  
Circular Cylinders ◽  
Square Cylinder ◽  
Saturation Regime ◽  
Time Dynamics ◽  
Significant Difference

The flow in the near wake of a square cylinder at Reynolds numbers of 205 and 225, corresponding to three-dimensional wake instability modes $A$ and $B$, respectively, and that of the square’s circumscribed circular cylinder are examined by using three-dimensional Navier–Stokes numerical simulations. At small times, prior to the streamwise vortex shedding, a self-similar velocity is observed in the wake and no significant difference is observed in the dynamics of the flows past the square and the circular cylinders. The exponential growth of the three-dimensional instability reaches a saturation regime during this early time for the considered Reynolds numbers. Vortical structures in the wake at long times and shedding frequencies are very close for the square and the circular cylinders. The flow separation on the forward top and bottom corners of the square cylinder have the effect of increasing its effective width, making it comparable with the diameter of the circumscribed circular cylinder. Thus, Floquet multipliers and modes of the associated three-dimensional instabilities are shown to be very close for the two cylinders when using the circumscribed circular cylinder as the basis for a characteristic length scale. Most importantly, the wavenumber with the maximum growth rate, for modes $A$ and $B$, is approximately identical for the two cylinders.

Three-dimensional instabilities in oscillatory flow past elliptic cylinders

2016 ◽  
Vol 798 ◽  
pp. 371-397 ◽  
Author(s):  
José P. Gallardo ◽  
Helge I. Andersson ◽  
Bjørnar Pettersen
Keyword(s):  
Circular Cylinder ◽  
Flow Direction ◽  
Three Dimensional ◽  
Circular Cylinders ◽  
Flow Structures ◽  
Three Dimensional Flow ◽  
Elliptical Cross ◽  
Dimensional Flow ◽  
Aspect Ratios ◽  
Flow Past

We investigate the early development of instabilities in the oscillatory viscous flow past cylinders with elliptic cross-sections using three-dimensional direct numerical simulations. This is a classical hydrodynamic problem for circular cylinders, but other configurations have received only marginal attention. Computed results for some different aspect ratios ${\it\Lambda}$ from 1 : 1 to 1 : 3, all with the major axis of the ellipse aligned in the main flow direction, show good qualitative agreement with Hall’s stability theory (J. Fluid Mech., vol. 146, 1984, pp. 347–367), which predicts a cusp-shaped curve for the onset of the primary instability. The three-dimensional flow structures for aspect ratios larger than 2 : 3 resemble those of a circular cylinder, whereas the elliptical cross-section with the lowest aspect ratio of 1 : 3 exhibits oblate rather than tubular three-dimensional flow structures as well as a pair of counter-rotating spanwise vortices which emerges near the tips of the ellipse. Contrary to a circular cylinder, instabilities for an elliptic cylinder with sufficiently high eccentricity emerge from four rather than two different locations in accordance with the Hall theory.

scholarly journals Heat Transfer Measurements and Predictions on a Power Generation Gas Turbine Blade

2000 ◽  
Author(s):  
Paul W. Giel ◽  
Ronald S. Bunker ◽  
G. James Van Fossen ◽  
Robert J. Boyle
Keyword(s):  
Heat Transfer ◽  
Power Generation ◽  
Three Dimensional ◽  
Thin Foil ◽  
Reynolds Numbers ◽  
Turbine Rotor ◽  
Stagnation Region ◽  
Design Point ◽  
Laminar To Turbulent Transition ◽  
Turbulent Transition

Detailed heat transfer measurements and predictions are given for a power generation turbine rotor with 129 deg of nominal turning and an axial chord of 137 mm. Data were obtained for a set of four exit Reynolds numbers comprised of the design point of 628,000, −20%, +20%, and +40%. Three ideal exit pressure ratios were examined including the design point of 1:378, −10%, and +10%. Inlet incidence angles of 0 deg and ±2 deg were also examined. Measurements were made in a linear cascade with highly three-dimensional blade passage flows that resulted from the high flow turning and thick inlet boundary layers. Inlet turbulence was generated with a blown square bar grid. The purpose of the work is the extension of three-dimensional predictive modeling capability for airfoil external heat transfer to engine specific conditions including blade shape, Reynolds numbers, and Mach numbers. Data were obtained by a steady-state technique using a thin-foil heater wrapped around a low thermal conductivity blade. Surface temperatures were measured using calibrated liquid crystals. The results show the effects of strong secondary vortical flows, laminar-to-turbulent transition, and also show good detail in the stagnation region.

The effects of surface roughness on the flow past circular cylinders at high Reynolds numbers

1982 ◽  
Vol 123 ◽  
pp. 363-378 ◽  
Author(s):  
Y. Nakamura ◽  
Y. Tomonari
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
High Reynolds Number ◽  
Circular Cylinders ◽  
Similarity Parameter ◽  
Number Range ◽  
Pressure Distributions ◽  
Mean Pressure ◽  
Supercritical Range ◽  
High Reynolds

Measurements of’ the mean-pressure distribution and the Strouhal number on a smooth circular cylinder, circular cylinders with distributed roughness, and circular cylinders with narrow roughness strips were made over a Reynolds-number range 4.0 × l04 to 1.7 × l06 in a uniform flow. A successful high-Reynolds-number (trans- critical) simulation for a smooth circular cylinder is obtained using a smooth circular cylinder with roughness strips. High-Reynolds-number simulation can only be obtained by roughness strips and not by distributed roughness. A similarity parameter correlating the pressure distributions on circular cylinders with distributed roughness in the supercritical range is presented. The same parameter can also be applicable to the drag coefficients of spheres with distributed roughness.

Efficient Operator Marching Method for Analyzing Crossed Arrays of Cylinders

2015 ◽  
Vol 18 (5) ◽  
pp. 1461-1481
Author(s):  
Yu Mao Wu ◽  
Ya Yan Lu
Keyword(s):  
Electromagnetic Field ◽  
Efficient Method ◽  
Periodic Structures ◽  
Three Dimensional ◽  
Circular Cylinders ◽  
Geometric Features ◽  
Spatial Direction ◽  
Number Of Layers ◽  
Crossed Arrays ◽  
Marching Method

AbstractPeriodic structures involving crossed arrays of cylinders appear as special three-dimensional photonic crystals and cross-stacked gratings. Such a structure consists of a number of layers where each layer is periodic in one spatial direction and invariant in another direction. They are relatively simple to fabricate and have found valuable applications. For analyzing scattering properties of such structures, general computational electromagnetics methods can certainly be used, but special methods that take advantage of the geometric features are often much more efficient. In this paper, an efficient method based on operators mapping electromagnetic field components between two spatial directions is developed to analyze structures with crossed arrays of circular cylinders. The method is much simpler than an earlier method based on similar ideas, and it does not require evaluating slowly converging lattice sums.

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