Comparison Between the Koopman Modes for the Flow Around Circular Cylinder and Circular Cylinder Fitted with Helical Strakes

2015 ◽  
pp. 117-122 ◽  
Author(s):  
Cesar M. Freire ◽  
Julio R. Meneghini ◽  
Rafael S. Gioria ◽  
Gustavo R. S. Assi
Keyword(s):  
Circular Cylinder ◽  
Helical Strakes ◽  
Flow Around Circular Cylinder

scholarly journals Numerical investigation of the flow around circular cylinder with two passive controls

2018 ◽  
Vol 974 ◽  
pp. 012011 ◽  
Author(s):  
Amirul Hakam ◽  
Basuki Widodo ◽  
Tri Yogi Yuwono ◽  
Chairul Imron
Keyword(s):  
Circular Cylinder ◽  
Numerical Investigation ◽  
Flow Around Circular Cylinder

Nonstationary, Three-Dimensional Aspects of Flow Around Circular Cylinder at Critical Reynolds Numbers

AIAA Journal ◽  
2011 ◽  
Vol 49 (9) ◽  
pp. 1857-1870 ◽  
Author(s):  
Ying-Ju Lin ◽  
Jiun-Jih Miau ◽  
Jung-Kuo Tu ◽  
Hsing-Wen Tsai
Keyword(s):  
Circular Cylinder ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Critical Reynolds Numbers ◽  
Flow Around Circular Cylinder

Model Test Study on Vortex-Induced Motions of a Floating Cylinder

2009 ◽  
Author(s):  
Ying Wang ◽  
Jianmin Yang ◽  
Tao Peng ◽  
Xin Li
Keyword(s):  
Circular Cylinder ◽  
Scale Model ◽  
Visualization System ◽  
Forced Motion ◽  
Drag Forces ◽  
Fluid Field ◽  
Helical Strakes ◽  
Induced Motion ◽  
Motion Characteristics ◽  
Lift And Drag

Vortex-Induced Motions (VIM) under current flow is an important issue for surface piercing cylinders, such as Spar platforms and floating buoys, since it affects the motion performance of these structures greatly. In recent years this phenomenon attracts much attention and many researchers have been making efforts to deal with this problem. VIM is such a complicated phenomenon that more fundamental studies are needed to understand the essence behind VIM. This paper mainly concentrates on a circular cylinder, aiming to eliminate outside influences and reveal the inherent characteristic of vortex-induced motion mechanism. A circular cylinder with an aspect ratio of 1:2.4, which could be considered as a scale model for the hard tank of a typical Truss Spar, is studied by experimental method to investigate the surrounding fluid field, the excitation forces and Vortex-Induced Motion characteristics under various governing parameters, such as the current velocity and direction, the mooring stiffness and distribution, the use and efficiency of helical strakes, and so on. By using a simple flow visualization system, the unsteady flow passing the circular cylinder and the vortices in the wake are captured and recorded. The cylinder is tested respectively under fixed, forced-motion and elastically moored conditions. The fluid field, the vortex structures, and the lift and drag forces under fixed and forced-motion conditions are measured, the VIM performance of the cylinder with two different mooring distributions are studied, and strake efficiency is studied considering current directionality and strake height influence.

721 Effects of Helical Strakes on Karman Vortex Shedding from a Circular Cylinder with Serrated Fin

2004 ◽  
Vol 2004 (0) ◽  
pp. _721-1_-_721-5_
Author(s):  
Hiromitsu HAMAKAWA ◽  
Tohru FUKANO ◽  
Masaki ANDO ◽  
Eiichi NISHIDA
Keyword(s):  
Circular Cylinder ◽  
Vortex Shedding ◽  
Helical Strakes ◽  
Karman Vortex

Study on Oscillated Flow around Circular Cylinder

2000 ◽  
Vol 2000.1 (0) ◽  
pp. 843-844
Author(s):  
Masaya KONDO ◽  
Yoshinari ANODA
Keyword(s):  
Circular Cylinder ◽  
Flow Around Circular Cylinder

VIV and WIV Suppression With Parallel Control Plates on a Pair of Circular Cylinders in Tandem

2009 ◽  
Author(s):  
Gustavo R. S. Assi ◽  
Peter W. Bearman
Keyword(s):  
Circular Cylinder ◽  
Drag Reduction ◽  
Flow Direction ◽  
Cross Flow ◽  
Offshore Structures ◽  
Circular Cylinders ◽  
Parallel Plates ◽  
Tandem Cylinders ◽  
Helical Strakes ◽  
Viv Suppression

Experiments have been carried out on two-dimensional devices fitted to a rigid length of circular cylinder to investigate the efficiency of pivoting parallel plates as wake-induced vibration suppressors. Measurements are presented for a circular cylinder with low mass and damping which is free to respond in the cross-flow direction. It is shown how VIV and WIV can be practically eliminated by using free to rotate parallel plates on a pair of tandem cylinders. Unlike helical strakes, the device achieves VIV suppression with 33% drag reduction when compare to a pair of fixed tandem cylinders at the same Reynolds number. These results prove that suppressors based on parallel plates have great potential to suppress VIV and WIV of offshore structures with considerable drag reduction.

scholarly journals Analysis of Flow over a Circular Cylinder Fitted with Helical Strakes

2016 ◽  
Vol 24 ◽  
pp. 452-460 ◽  
Author(s):  
E.R. Ranjith ◽  
A.S. Sunil ◽  
Lippin Pauly
Keyword(s):  
Circular Cylinder ◽  
Helical Strakes
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