Three-Dimensional Numerical Simulations of Circular Cylinders Undergoing Two Degree-of-Freedom Vortex-Induced Vibrations

2006 ◽  
Author(s):  
Juan P. Pontaza ◽  
Hamn-Ching Chen
Keyword(s):  
Numerical Simulations ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Degree Of Freedom ◽  
Circular Cylinders ◽  
Time Step ◽  
Reynolds Number Flow ◽  
Number Flow ◽  
High Reynolds ◽  
Two Degree Of Freedom

In an effort to gain a better understanding of the VIV phenomena, we present three-dimensional numerical simulations of VIV of circular cylinders. We consider operating conditions that correspond to high Reynolds number flow, low structural damping, and allow for two-degree of freedom motion. The numerical implementation makes use of overset (Chimera) grids, in a multiple block environment where the workload associated with the blocks is distributed among multiple processors working in parallel. The three-dimensional grids around the cylinder are allowed to undergo arbitrary motions with respect to fixed background grids, eliminating the need for tedious grid regeneration at every time step.

Three-Dimensional Numerical Simulations of Circular Cylinders Undergoing Two Degree-of-Freedom Vortex-Induced Vibrations

2006 ◽  
Vol 129 (3) ◽  
pp. 158-164 ◽  
Author(s):  
Juan P. Pontaza ◽  
Hamn-Ching Chen
Keyword(s):  
Numerical Simulations ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Degree Of Freedom ◽  
Circular Cylinders ◽  
Numerical Implementation ◽  
Vortex Induced Vibrations ◽  
Multiple Processors ◽  
Structural Mass ◽  
Two Degree Of Freedom

In an effort to gain a better understanding of vortex-induced vibrations (VIV), we present three-dimensional numerical simulations of VIV of circular cylinders. We consider operating conditions that correspond to a Reynolds number of 105, low structural mass and damping (m*=1.0, ζ*=0.005), a reduced velocity of U*=6.0, and allow for two degree-of-freedom (X and Y) motion. The numerical implementation makes use of overset (Chimera) grids, in a multiple block environment where the workload associated with the blocks is distributed among multiple processors working in parallel. The three-dimensional grid around the cylinder is allowed to undergo arbitrary motions with respect to fixed background grids, eliminating the need for grid regeneration as the structure moves on the fluid mesh.

Vortex Suppression Efficiency of Discontinuous Helicoidal Fins

2007 ◽  
Author(s):  
Antonio Pinto ◽  
Riccardo Broglia ◽  
Elena Ciappi ◽  
Andrea Di Mascio ◽  
Emilio F. Campana ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Computational Time ◽  
Reynolds Number Flow ◽  
Flow Past A Cylinder ◽  
Helical Strakes ◽  
Unsteady Rans ◽  
Number Flow ◽  
Offshore Industry ◽  
Good Trade ◽  
High Reynolds

Vortex-Induced Vibration (VIV) is one of the most demanding areas in the offshore industry, and detailed investigation of the fluid-structure interaction is becoming fundamental for designing new structures able to reduce VIV phenomenon. To carry on such analysis, and get reliable results in term of global coefficients, the correct modelling of turbulence, boundary layer, and separated flows is required. Nonetheless, the more accurate is the simulation, the more costly is the computation. Unsteady RANS simulations provide a good trade-off between numerical accuracy and computational time. This paper presents the analysis of the flow past a cylinder with several three-dimensional helical fins at high Reynolds number. Flow field, vortical structures, and response frequency patterns are analysed. Spectral analysis of data is performed to identify carrier frequencies, deemed to be critical due to the induced vibration of the whole structure. Finally, helical strakes efficiency in reducing the riser vibrations is also addressed, through direct consideration on the carrier shedding frequency.

Coherent structures in coflowing jets and wakes

1978 ◽  
Vol 88 (3) ◽  
pp. 451-463 ◽  
Author(s):  
A. E. Perry ◽  
T. T. Lim
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Glass Tube ◽  
Reynolds Numbers ◽  
Reynolds Number Flow ◽  
Naturally Occurring ◽  
Number Flow ◽  
High Reynolds ◽  
Scale Motion

By applying small lateral oscillations to a glass tube from which smoke was issuing, perfectly periodic coflowing jets and wake structures were produced at Reynolds numbers of order 300-1000. These structures remained coherent over long streamwise distances and appeared to be perfectly frozen when viewed under stroboscopic light which was synchronized with the disturbing oscillation. By the use of strobing laser beams, longitudinal sections of the structures were photographed and an account of the geometry of these structures is reported.When the tube was unforced, similar structures occurred but they modulated in scale and frequency, and their orientation was random.A classification of structures is presented and examples are demonstrated in naturally occurring situations such as smoke from a cigarette, the wake behind a three-dimensional blunt body, and the high Reynolds number flow in a plume from a chimney. It is suggested that an examination of these structures may give some insight into the large-scale motion in fully turbulent flow.

The interacting boundary-layer flow due to a vortex approaching a cylinder

1997 ◽  
Vol 346 ◽  
pp. 319-343 ◽  
Author(s):  
Z. XIAO ◽  
O. R. BURGGRAF ◽  
A. T. CONLISK
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Boundary Layer Separation ◽  
Two Dimensions ◽  
Unsteady Boundary Layer ◽  
Reynolds Number Flow ◽  
Boundary Layer Equations ◽  
Number Flow ◽  
Layer Flow ◽  
High Reynolds

In this paper the solution to the three-dimensional and unsteady interacting boundary-layer equations for a vortex approaching a cylinder is calculated. The flow is three-dimensional and unsteady. The purpose of this paper is to enhance the understanding of the structure in three-dimensional unsteady boundary-layer separation commonly observed in a high-Reynolds-number flow. The short length scales associated with the boundary-layer eruption process are resolved through an efficient and effective moving adaptive grid procedure. The results of this work suggest that like its two-dimensional counterpart, the three-dimensional unsteady interacting boundary layer also terminates in a singularity at a finite time. Furthermore, the numerical calculations confirm the theoretical analysis of the singular structure in two dimensions for the interacting boundary layer due to Smith (1988).

Three-Dimensional Numerical Simulations of Flows Past Smooth and Rough/Bare and Helically Straked Circular Cylinders Allowed to Undergo Two Degree-of-Freedom Motions

2007 ◽  
Author(s):  
Juan P. Pontaza ◽  
Raghu G. Menon ◽  
H. C. Chen
Keyword(s):  
Reynolds Number ◽  
Turbulence Model ◽  
Cross Flow ◽  
Operating Conditions ◽  
Degree Of Freedom ◽  
Circular Cylinders ◽  
Navier Stokes ◽  
Wall Region ◽  
Roughness Effects ◽  
Two Degree Of Freedom

We simulate the flow past smooth and rough rigid circular cylinders that are either bare or outfitted with helical stakes. We consider operating conditions that correspond to high Reynolds numbers of 105 and 106, and allow for two degree-of-freedom motions when the structure is allowed to respond to vortex-induced cross flow and in-line forces. The computations are performed using a parallelized Navier-Stokes in-house solver using overset grids. For smooth surface simulations at a Reynolds number of 105, we use a Smagorinsky Large Eddy Simulation (LES) turbulence model and for the Reynolds number cases of 106 we make use of the unsteady Reynolds-Averaged Navier-Stokes (URANS) equations with a two-layer k-epsilon turbulence model. The rough surface modifications of the two-layer k-epsilon turbulence model due to Durbin et al. (ASME J. Fluids Eng., 2001) are implemented to account for surface roughness effects. In all our computations we aim to resolve the boundary layer directly by using adequate grid spacing in the near-wall region. The predicted global flow parameters under different surface conditions are in good agreement with experimental data and significant VIV suppression is observed when using helically straked cylinders.

Three-Dimensional Numerical Simulations of Flows Past Smooth and Rough/Bare and Helically Straked Circular Cylinders Allowed to Undergo Two Degree-of-Freedom Motions

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Juan P. Pontaza ◽  
Raghu G. Menon ◽  
Hamn-Ching Chen
Keyword(s):  
Reynolds Number ◽  
Turbulence Model ◽  
Stokes Equations ◽  
Operating Conditions ◽  
Degree Of Freedom ◽  
Circular Cylinders ◽  
Navier Stokes ◽  
Wall Region ◽  
Roughness Effects ◽  
Two Degree Of Freedom

We simulate the flow past smooth and rough rigid circular cylinders that are either bare or outfitted with helical strakes. We consider operating conditions that correspond to high Reynolds numbers of 105 and 106, and allow for two degree-of-freedom motions such that the structure is allowed to respond to flow-induced cross-flow and in-line forces. The computations are performed using a parallelized Navier–Stokes in-house solver using overset grids. For smooth surface simulations at a Reynolds number of 105, we use a Smagorinsky large eddy simulation turbulence model and for the Reynolds number cases of 106 we make use of the unsteady Reynolds-averaged Navier–Stokes equations with a two-layer k-epsilon turbulence model. The rough surface modifications of the two-layer k-epsilon turbulence model due to Durbin et al. (2001, “Rough Wall Modification of Two-Layer k-Epsilon,” ASME J. Fluids Eng., 123, pp. 16–21) are implemented to account for surface roughness effects. In all our computations we aim to resolve the boundary layer directly by using adequate grid spacing in the near-wall region. The predicted global flow parameters under different surface conditions are in good agreement with experimental data, and significant vortex-induced vibration suppression is observed when using helically straked cylinders.

Sign in / Sign up

Export Citation Format

Share Document