scholarly journals Lagrangian and Eulerian dataset of the wake downstream of a smooth cylinder at a Reynolds number equal to 3900

Data in Brief ◽  
2021 ◽  
pp. 107725
Author(s):  
Ali Rahimi Khojasteh ◽  
Sylvain Laizet ◽  
Dominique Heitz ◽  
Yin Yang
Keyword(s):  
Reynolds Number ◽  
Smooth Cylinder

Hydrodynamic Coefficients of Cylinders With Strakes in Oscillatory Flows

2006 ◽  
Author(s):  
Renjeev Gopalakrishnakurup ◽  
David Clelland ◽  
Shan Huang
Keyword(s):  
Reynolds Number ◽  
Digital Signal ◽  
Water Tank ◽  
Hydrodynamic Coefficients ◽  
Oscillatory Flows ◽  
Signal Filtering ◽  
Test Matrix ◽  
Smooth Cylinder ◽  
Calm Water ◽  
Pitch Ratio

Hydrodynamic coefficients of cylinders fitted with strakes in oscillatory flows have been investigated. Three different pitch ratios have been tested, i.e. pitch ratios of infinity, 8 and 4. The cylinders are forced to oscillate in otherwise calm water in a water tank. To validate as well as to compare the experiment results, a smooth cylinder is included in the test matrix. Digital signal filtering has been found to influence the results obtained. Hence sine-fitted signals are used for obtaining the coefficients. For cylinders with strakes, it has been found that the coefficients vary little with Reynolds number. It is also concluded that the pitch ratio has a significant impact on the hydrodynamic coefficients.

Flow Past Circular Cylinder With Different Surface Configurations

1992 ◽  
Vol 114 (2) ◽  
pp. 170-177 ◽  
Author(s):  
Y. C. Leung ◽  
N. W. M. Ko ◽  
K. M. Tang
Keyword(s):  
Reynolds Number ◽  
Groove Surface ◽  
Number Range ◽  
Pressure Distributions ◽  
Downward Shift ◽  
Reynolds Number Range ◽  
Lower Reynolds Number ◽  
Smooth Cylinder ◽  
Mean Pressure ◽  
The Mean

Measurements of the mean pressure distributions and Strouhal numbers on partially grooved cylinders with different groove subtend angles were made over a Reynolds number range of 2.0×104 to 1.3×105 which was within the subcritical regime of smooth cylinder. The Strouhal number, pressure distributions, and their respective coefficients were found to be a function of the groove subtend angles. In general, a progressive shift of the flow regime to lower Reynolds number was observed with higher subtend angle and a subtend angle of 75 deg was found for optimum drag reduction. With the configuration of asymmetrical groove surface, lower drag, and higher lift coefficients were obtained within the same Reynolds number range. Wake traverse and boundary layer results of the asymmetric grooved cylinder indicated that the flows at the smooth and groove surfaces lied within different flow regimes and a downward shift of the wake.

Numerical Study on the Flow Past a Twisted Elliptic Cylinder With Subcritical Reynolds Number

2011 ◽  
Author(s):  
Min Ho Kim ◽  
Jin Woog Lee ◽  
Hyun Sik Yoon ◽  
Man Yeong Ha
Keyword(s):  
Reynolds Number ◽  
Numerical Study ◽  
Elliptic Cylinder ◽  
Cross Sectional Area ◽  
Stream Velocity ◽  
Spanwise Direction ◽  
Sectional Area ◽  
Cross Sectional ◽  
Flow Past ◽  
Smooth Cylinder

Large eddy simulation of flow past a torsional cylinder has been carried out at a Reynolds number of 3900 based on the cylinder diameter and the free stream velocity using finite volume method. The torsional cylinder has been formed by rotating the elliptic cross sectional area along the spanwise direction. For an ellipse, different eccentricities are considered to observe the effect of eccentricity on the flow fields. The excellent comparisons with previous studies for the cases of a smooth cylinder and a wavy cylinder having sinusoidal variation in cross sectional area along the spanwise direction guarantee the accuracy of present numerical methods. The effect of eccentricity on the drag and lift coefficients representing the fluid flow characteristics has been investigated by comparing with those of the smooth cylinder, resulting in enhancement of drag reduction and suppression of vortex-induced vibration. The isosurface of swirling strength has been adopted to identify the vortical structures in the turbulent wake.

scholarly journals MARINE ROUGHENED CYLINDER WAVE FORCE COEFFICIENTS

1984 ◽  
Vol 1 (19) ◽  
pp. 182
Author(s):  
John H. Nath
Keyword(s):  
Reynolds Number ◽  
Laboratory Testing ◽  
Wave Force ◽  
Periodic Waves ◽  
Transfer Coefficients ◽  
Cylinder Diameter ◽  
Force Transfer ◽  
Smooth Cylinder ◽  
One Year ◽  
Very High

Steel cylinders were submerged on a platform in the South Pass region of the Gulf of Mexico for one year to accumulate biofouling for later laboratory testing to determine wave force transfer coefficients. They were positioned at -55, -140, and -190 feet below the still water surface. Laboratory tests comprised steady tow up to Reynolds number cd 7x10^, and periodic waves up to Reynolds number of 1.6x10 and Keulegan-Carpenter number up to 25. The force transfer coefficients for the -55 cylinder were about equal to those for a sand roughened cylinder with relative cylinder roughness, e/D, of .03, where e is the height of the equivalent sand roughness size and D is the smooth cylinder diameter. The drag coefficient for very high Keulegan-Carpenter number, or steady tow, is about 1.0 if the effective cylinder diameter is taken into account, for the rougher cylinders.

Oscillating Flow About Smooth and Rough Cylinders

1987 ◽  
Vol 109 (4) ◽  
pp. 307-313 ◽  
Author(s):  
Turgut Sarpkaya
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Coherence Length ◽  
Lift Force ◽  
Diameter Ratio ◽  
Oscillating Flow ◽  
Force Coefficients ◽  
Smooth Cylinder ◽  
Cylinder Drag ◽  
Length To Diameter Ratio

The lift, drag, and inertia coefficients and the first ten harmonics of the lift force have been determined through the use of four smooth, four sand-roughened, and one marine-roughened cylinders. The length-to-diameter ratio of the smooth and sand-roughened cylinders was kept constant (L/D = 2) in order to determine the effect of coherence length on the force coefficients. The Keulegan-Carpenter number ranged from about 1 to 60 and the Reynolds number from about 2500 to 800,000. The results have shown that (i) the smooth cylinder data agree quite well with those presented by Sarpkaya [1, 2] and Rodenbusch and Gutierrez [3]; (ii) the drag and inertia coefficients for rough cylinders (k/D = 1/50) become independent of β (= D2/vT) or of the Reynolds number (Re = UmD/v) for β larger than about 4000; (iii) the rough-cylinder data agree quite well within those reported by Sarpkaya [2] and show that the effect of roughness is indeed very profound; and (iv) the rough-cylinder drag-coefficient data of Rodenbusch and Gutierrez [3] are somewhat larger than those obtained in the present investigation.

scholarly journals Study of the Drag Reduction Characteristics of Circular Cylinder with Dimpled Surface

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 197
Author(s):  
Fei Yan ◽  
Haifeng Yang ◽  
Lihui Wang
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Drag Reduction ◽  
Skin Friction ◽  
Vortex Shedding ◽  
Pressure Coefficient ◽  
Reduction Rate ◽  
Skin Friction Coefficient ◽  
Pressure Drag ◽  
Smooth Cylinder

To reduce the drag of a cylinder, numerical simulations and experiments for both smooth cylinder and circular cylinder with the dimpled surface are carried out in this paper. The numerical simulation focuses on the variation of pressure coefficient, skin friction coefficient, and vortex shedding strength of the smooth cylinder and the circular cylinder with the dimpled surface. It is found that the dimpled structure can effectively reduce the drag of the cylinder within a specific range of Reynolds number, and the maximum drag reduction rate reaches up to 19%. Another conclusion is that the pressure drag and skin friction drag have an essential influence on the total drag of the circular cylinder with the dimpled surface. On the other hand, the strength of vortex shedding also decreases with the decrease of cylinder drag. Then, the flow field of both cylinders is measured using the particle image velocimetry (PIV) technique, confirming that the dimpled structure can affect the velocity field, the release of vortices and the scale of the vortex. More specifically, the velocity recovery of the circular cylinder with the dimpled surface is faster than that of the smooth cylinder, and the dimpled structure delays the release of the vortex at a specific range of Reynolds number.

scholarly journals RANS and SRS simulations of the flow around a smooth cylinder

2020 ◽  
Vol 310 ◽  
pp. 00031
Author(s):  
Ivan Kološ ◽  
Lenka Lausová ◽  
Vladimíra Michalcová
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Simulation Models ◽  
Computational Domain ◽  
3D Mesh ◽  
Smooth Cylinder ◽  
Flow Around Circular Cylinder ◽  
2D And 3D

The paper focuses on the numerical simulation of the flow around circular cylinder with Reynolds number 2∙104. The 2D and 3D mesh is used for the computational domain. RANS turbulence model SST k-ω is used for the 2D task. The 3D task is solved using Scale-Resolving Simulation models LES, SAS, DES. Drag coefficient, lift coefficient, pressure coefficient and velocity field in the wake are evaluated.

scholarly journals Large Eddy Simulation of Flow over Wavy Cylinders with Different Twisted Angles at a Subcritical Reynolds Number

2019 ◽  
Vol 7 (7) ◽  
pp. 227 ◽  
Author(s):  
Chunyu Guo ◽  
Hang Guo ◽  
Jian Hu ◽  
Kewei Song ◽  
Weipeng Zhang ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Large Eddy Simulation ◽  
Vortex Structure ◽  
Pressure Coefficient ◽  
Vortex Formation ◽  
Spanwise Direction ◽  
Offshore Platforms ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Smooth Cylinder

The deformation of the cylinder has been proved to greatly reduce the fluctuation of lift and the vortex-induced vibration. In this article, a new form of deformation mode for the smooth cylinder is proposed in order to reduce the vortex-induced vibrations, which can be applied to marine risers and submarine pipelines to ensure the working performance and safety of offshore platforms. Large eddy simulation (LES) is adopted to simulate the turbulent flow over wavy cylinders with three different twisted angles at a subcritical Reynolds number Re = 28,712. Comparing with the results of smooth cylinder, the maximum drag and lift reduction of wavy cylinder A3 with α = 40° can reach 17% and 84%, respectively, and the corresponding vortex formation length increases significantly, while the turbulence intensity decreases relatively. Meanwhile, the circumferential minimum pressure coefficient is greater than that of the smooth cylinder, which also provides a greater drag reduction for the cylinder. The surface separation line, turbulent kinetic energy distribution, and wake vortex structure indicate that the elongation of separated shear layer and wake shedding position is larger than that of the smooth cylinder, and the vorticity value in the near wake region decreases. A periodic vortex structure is generated along the spanwise direction, and a weaker and more stable Karman vortex street is reformed at a further downstream position, which ultimately leads to the reduction of drag and fluctuating lift of the wavy cylinder.

Sign in / Sign up

Export Citation Format

Share Document