On the Flow Characteristics around a Circular Cylinder according as the Water Depth from the Free Surface

2010 ◽  
Vol 34 (5) ◽  
pp. 331-336
Author(s):  
Ok-Sok Gim ◽  
Chang-Bae Shon ◽  
Gyoung-Woo Lee
Keyword(s):  
Free Surface ◽  
Circular Cylinder ◽  
Water Depth ◽  
Flow Characteristics

Centrifugal waves

1960 ◽  
Vol 7 (3) ◽  
pp. 340-352 ◽  
Author(s):  
O. M. Phillips
Keyword(s):  
Free Surface ◽  
Angular Velocity ◽  
Circular Cylinder ◽  
Rigid Body ◽  
Water Depth ◽  
Frequency Equation ◽  
Rigid Rotation ◽  
Body Motion ◽  
Small Perturbations ◽  
The Stability

When a hollow circular cylinder with its axis horizontal is partially filled with water and rotated rapidly about its axis, an almost rigid-body motion results with an interior free surface. The emotion is analysed assuming small perturbations to a rigid rotation, and a criterion is found for the stability of the motion. This is confirmed experimentally under varying conditions of water depth and angular velocity of the cylinder. The modes of oscillation (centrifugal waves) of the free surface are examined and a frequency equation deduced. Two particular modes are considered in detail, and satisfactory agreement is found with the frequencies observed.

Low Reynolds Flow Past a Circular Cylinder Close to a Free-Surface With Vertical Motion Dynamics

2016 ◽  
Author(s):  
Jose L. Cercos-Pita ◽  
Andrea Colagrossi ◽  
Antonio Souto-Iglesias
Keyword(s):  
Free Surface ◽  
Circular Cylinder ◽  
Lift Coefficient ◽  
Flow Characteristics ◽  
Vertical Motion ◽  
Bluff Bodies ◽  
Flow Past ◽  
Low Reynolds ◽  
Work Done ◽  
Large Response

Flow past a circular cylinder close to a free surface at low Reynolds number is investigated numerically in this paper extending the work done in previous 2014 and 2015 OMAE papers [1, 2]. In the former, the dependence of the flow with the submergence was discussed and in the latter the flow at high Froude numbers was investigated. It was found that shedding is blocked as the cylinder approaches de free surface with an increasing value of the net lift coefficient and a reduction of the lift alternate oscillations due to such shedding. This variation on the lift pattern suggests that if a VIVACE device [3] is set under these flow characteristics, its performance will significantly differ from that in deep water conditions. These devices take advantage of flow induced motions in bluff bodies (such as the cylinder) to generate electric power. Singh & Mittal [4] coupled VIV system is studied in present paper in the presence of a free surface, selecting a configuration with large response in unbounded flow and adding a free-surface to such case. Results are presented and discussed.

scholarly journals Free-surface flow simulations for discharge-based operation of hydraulic structure gates

2013 ◽  
Vol 16 (1) ◽  
pp. 189-206 ◽  
Author(s):  
C. D. Erdbrink ◽  
V. V. Krzhizhanovskaya ◽  
P. M. A. Sloot
Keyword(s):  
Free Surface ◽  
Hydraulic Structure ◽  
Flow Characteristics ◽  
Surface Flow ◽  
Water Levels ◽  
Surface Model ◽  
Local Flow ◽  
Gate Operation ◽  
Flow Equations ◽  
Flow Simulations

We combine non-hydrostatic flow simulations of the free surface with a discharge model based on elementary gate flow equations for decision support in the operation of hydraulic structure gates. A water level-based gate control used in most of today's general practice does not take into account the fact that gate operation scenarios producing similar total discharged volumes and similar water levels may have different local flow characteristics. Accurate and timely prediction of local flow conditions around hydraulic gates is important for several aspects of structure management: ecology, scour, flow-induced gate vibrations and waterway navigation. The modelling approach is described and tested for a multi-gate sluice structure regulating discharge from a river to the sea. The number of opened gates is varied and the discharge is stabilized with automated control by varying gate openings. The free-surface model was validated for discharge showing a correlation coefficient of 0.994 compared to experimental data. Additionally, we show the analysis of computational fluid dynamics (CFD) results for evaluating bed stability and gate vibrations.

Fluid Structure Interaction Simulations Involving Free Surface

2018 ◽  
Author(s):  
H. R. Díaz-Ojeda ◽  
L. M. González ◽  
F. J. Huera-Huarte
Keyword(s):  
Free Surface ◽  
Circular Cylinder ◽  
Fluid Structure Interaction ◽  
Flexible Structure ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Classical Fluid ◽  
Simple Geometry ◽  
Different Depths

The aim of this paper is to evaluate how much affects the presence of gravity and free-surface to a flexible structure in a classical fluid structure interaction (FSI) problem typically found in off-shore problems and other oceanic applications. The base problem selected is the Turek benchmark case where a deformable plate is attached to the wake of a circular cylinder. To focus on the differences of considering free surface, a simple geometry has been selected and two different situations have been studied: the first one is the classical Turek benchmark, the second is a similar geometry but adding gravity and free surface. The free surface problem was studied placing the structure at different depths and monitoring the deformation and forces on the structure.

scholarly journals Dam-Break Flows: Comparison between Flow-3D, MIKE 3 FM, and Analytical Solutions with Experimental Data

2018 ◽  
Vol 8 (12) ◽  
pp. 2456 ◽  
Author(s):  
Hui Hu ◽  
Jianfeng Zhang ◽  
Tao Li
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Analytical Solution ◽  
Water Depth ◽  
3D Model ◽  
Real Life ◽  
Surface Profile ◽  
Dam Break ◽  
Computational Time ◽  
Free Surface Profile

The objective of this study was to evaluate the applicability of a flow model with different numbers of spatial dimensions in a hydraulic features solution, with parameters such a free surface profile, water depth variations, and averaged velocity evolution in a dam-break under dry and wet bed conditions with different tailwater depths. Two similar three-dimensional (3D) hydrodynamic models (Flow-3D and MIKE 3 FM) were studied in a dam-break simulation by performing a comparison with published experimental data and the one-dimensional (1D) analytical solution. The results indicate that the Flow-3D model better captures the free surface profile of wavefronts for dry and wet beds than other methods. The MIKE 3 FM model also replicated the free surface profiles well, but it underestimated them during the initial stage under wet-bed conditions. However, it provided a better approach to the measurements over time. Measured and simulated water depth variations and velocity variations demonstrate that both of the 3D models predict the dam-break flow with a reasonable estimation and a root mean square error (RMSE) lower than 0.04, while the MIKE 3 FM had a small memory footprint and the computational time of this model was 24 times faster than that of the Flow-3D. Therefore, the MIKE 3 FM model is recommended for computations involving real-life dam-break problems in large domains, leaving the Flow-3D model for fine calculations in which knowledge of the 3D flow structure is required. The 1D analytical solution was only effective for the dam-break wave propagations along the initially dry bed, and its applicability was fairly limited.

Flow characteristics of two rotating side-by-side circular cylinder

2009 ◽  
Vol 38 (2) ◽  
pp. 466-474 ◽  
Author(s):  
Hyun Sik Yoon ◽  
Ho Hwan Chun ◽  
Jeong Hu Kim ◽  
I.L. Ryong Park
Keyword(s):  
Circular Cylinder ◽  
Flow Characteristics
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