Numerial Study of Vortex-Induced Vibration of Circular Cylinder Adjacent to Plane Boundary Using Direct-Forcing Immersed Boundary Method

2017 ◽  
Vol 34 (2) ◽  
pp. 177-191
Author(s):  
M. J. Chern ◽  
G. T. Lu ◽  
Y. H. Kuan ◽  
S. Chakraborty ◽  
G. Nugroho ◽  
...  
Keyword(s):  
Circular Cylinder ◽  
Skin Friction ◽  
Boundary Effect ◽  
Physical Phenomenon ◽  
Plane Boundary ◽  
Immersed Boundary ◽  
Single Vortex ◽  
Vortex Induced Vibration ◽  
Cylindrical Structure ◽  
Direct Forcing

AbstractVortex-induced vibration (VIV) is an important physical phenomenon as one design a riser or a cylindrical structure in ocean. As the riser or the cylindrical structure is adjacent to a seabed, the boundary effect on VIV is not fully understood yet. The direct-forcing immersed boundary (DFIB) method is used to investigate a two-degree-of-freedom VIV of a flexible supported circular cylinder adjacent to a plane boundary in this study. Furthermore, the effect of the VIV of cylinder on skin friction of the plane boundary is investigated. The effects of varying reduced velocity and gap ratio on VIV are discussed. Only a single vortex street is found when the cylinder is close to plane boundary. Hydrodynamic coefficients of the freely vibrating cylinder are analyzed in time and spectral domains. Furthermore, nearly round oval-shaped motion is observed as the so-called lock-in phenomenon occurs. The skin friction of the plane boundary is predicted by the DFIB model. Results show that the vibrating cylinder in the boundary layer flow can reduce the friction effectively. This proposed DFIB model can be useful for the investigation of VIV of the structures under the plane boundary effect even for a small gap between the cylinder and the boundary.

Direct-forcing immersed boundary modeling of vortex-induced vibration of a circular cylinder

2014 ◽  
Vol 134 ◽  
pp. 109-121 ◽  
Author(s):  
Ming-Jyh Chern ◽  
Yu-Hao Kuan ◽  
Giri Nugroho ◽  
Guan-Ting Lu ◽  
Tzyy-Leng Horng
Keyword(s):  
Circular Cylinder ◽  
Immersed Boundary ◽  
Vortex Induced Vibration ◽  
Direct Forcing

Numerical Investigation of Vortex-Induced Vibration of a Circular Cylinder Close to a Plane Boundary

2010 ◽  
Author(s):  
Ming Zhao ◽  
Liang Cheng
Keyword(s):  
Experimental Data ◽  
Circular Cylinder ◽  
Vortex Shedding ◽  
Stokes Equations ◽  
Degree Of Freedom ◽  
Plane Boundary ◽  
Structural Dynamic ◽  
Vortex Induced Vibration ◽  
Two Degree Of Freedom ◽  
Bounce Back

Two-degree of freedom vortex-induced vibration (VIV) of a circular cylinder close to a plane boundary is investigated numerically. Two-dimensional (2D) Reynolds-Averaged Navier-Stokes Equations (RANS) and structural dynamic equation are solved using a finite element method (FEM). If the cylinder is initially very close to the plane boundary, it will be bounced back after it collides with boundary. It is assumed that the bouncing back only alters the cylinder’s velocity component perpendicular to the boundary. After it is bounced back, the cylinder’s velocity are determined by Uc = Uc′, Vc = −bVc′, where Uc and Vc are the cylinder’s velocity parallel to the boundary and that perpendicular to the boundary respectively, Uc′ and Vc′ are the velocities before cylinder is bounced back, b is the bounce back coefficient which is between 0 and 1. Numerical results of the vibration amplitude and frequency of a one-degree-of-freedom vibration (transverse to flow direction) of a circular cylinder close to a plane boundary are compared with the experimental data by Yang et al. [1]. The overall trends of the variation of the VIV amplitude with the reduced velocity were found to be in agreement with the experimental results. The calculated amplitude is smaller than the measured data. The frequency of the vibration increases with the increase of reduced velocity. The calculated vibrating frequency agrees well with the experimental data. It was found in this study that vortex-induced vibration (VIV) occurs even when the gap between the cylinder and the plane boundary is zero. This contradicts a perception that VIV would not occur for a pipeline close to the seabed with a gap ratio smaller than 0.3, this is because it was understood that vortex shedding would have been suppressed if the gap between the cylinder and the plane boundary is less than about 0.3 times of cylinder diameter for a fixed cylinder. Two-degree-of-freedom VIV of a circular cylinder close to a plane boundary is studied. The XY-trajectories, the frequency and the amplitude of the vibration are studied. The effects of the cylinder-to-boundary gap and the bounce back coefficient on VIV and the link between the vortex shedding mode and the VIV are discussed.

Numerical Investigation of Vortex-Induced Vibration of a Circular Cylinder Close to a Plane Boundary Subject to Oscillatory Flow

2016 ◽  
Author(s):  
Adnan Munir ◽  
Ming Zhao ◽  
Helen Wu
Keyword(s):  
Circular Cylinder ◽  
Oscillatory Flow ◽  
Numerical Study ◽  
Cross Flow ◽  
Navier Stokes ◽  
Plane Boundary ◽  
Vortex Induced Vibration ◽  
Gap Ratio ◽  
Wide Range ◽  
Close Proximity

This paper presents a numerical study of flow around an elastically mounted circular cylinder in close proximity to a plane boundary vibrating in the transverse and inline directions in an oscillatory flow. The Reynolds-Averaged Navier-Stokes (RANS) equations and the SST k-ω turbulent equations are solved using the Arbitrary Langrangian-Eulerian (ALE) scheme and Petrov-Galerkin Finite Element Method for simulating the flow. The equation of motion is solved using the fourth-order Runge-Kutta method to find the displacements of the cylinder in the transverse and inline directions. The numerical model is validated against the previous results of vortex-induced vibration of an isolated circular cylinder in both cross-flow and inline directions. The flow model is further extended to study the vortex-induced vibration of a cylinder near a plane boundary with a very small gap ratio (e/D) of 0.01, with D and e being the diameter and the gap between the cylinder and the plane boundary, respectively. Simulations are carried out for two Keulegan-Carpenter (KC) numbers of 5 and 10 and a wide range of reduced velocities. It is observed that both the KC number and the reduced velocity affect the vibration of the cylinder significantly.

Direct-Forcing Immersed Boundary Method for Mixed Heat Transfer

2015 ◽  
Vol 18 (4) ◽  
pp. 1072-1094 ◽  
Author(s):  
Ming-Jyh Chern ◽  
Dedy Zulhidayat Noor ◽  
Ching-Biao Liao ◽  
Tzyy-Leng Horng
Keyword(s):  
Circular Cylinder ◽  
Energy Transport ◽  
Current Method ◽  
Navier Stokes ◽  
Immersed Boundary ◽  
Solid Object ◽  
Square Enclosure ◽  
Virtual Force ◽  
Direct Forcing ◽  
The Right

AbstractA direct-forcing immersed boundary method (DFIB) with both virtual force and heat source is developed here to solve Navier-Stokes and the associated energy transport equations to study some thermal flow problems caused by a moving rigid solid object within. The key point of this novel numerical method is that the solid object, stationary or moving, is first treated as fluid governed by Navier-Stokes equations for velocity and pressure, and by energy transport equation for temperature in every time step. An additional virtual force term is then introduced on the right hand side of momentum equations in the solid object region to make it act exactly as if it were a solid rigid body immersed in the fluid. Likewise, an additional virtual heat source term is applied to the right hand side of energy equation at the solid object region to maintain the solid object at the prescribed temperature all the time. The current method was validated by some benchmark forced and natural convection problems such as a uniform flow past a heated circular cylinder, and a heated circular cylinder inside a square enclosure. We further demonstrated this method by studying a mixed convection problem involving a heated circular cylinder moving inside a square enclosure. Our current method avoids the otherwise requested dynamic grid generation in traditional method and shows great efficiency in the computation of thermal and flow fields caused by fluid-structure interaction.

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