A numerical study on turbulent vortex‐shedding flows around a cubical form

The wave-induced resonant flow in a narrow gap between a stationary hull and a vertical wall is studied experimentally and numerically. Vortex shedding from the sharp bilge edge of the hull gives rise to a quadratically damped free surface response in the gap, where the damping coefficient is approximately independent of wave steepness and frequency. Particle image velocimetry and direct numerical simulations were used to characterise the shedding dynamics and explore the influence of discretisation in the measurements and computations. Secondary separation was identified as a particular feature which occurred at the hull bilge in these gap flows. This can result in the generation of a system with multiple vortical regions and asymmetries between the inflow and outflow. The shedding dynamics was found to exhibit a high degree of invariance to the amplitude in the gap and the spanwise position of the barge. The new measurements and the evaluation of numerical models of varying fidelity can assist in informing offshore operations such as the side by side offloading from floating liquefied natural gas facilities.

Download Full-text

Numerical Prediction of Turbulent Wakes Behind a Square Cylinder

Journal of Mechanics ◽

10.1017/s1727719100000034 ◽

1998 ◽

Vol 14 (1) ◽

pp. 23-29

Author(s):

Robert R. Hwang ◽

Sheng-Yuh Jaw

Keyword(s):

Stokes Equations ◽

Numerical Study ◽

Navier Stokes ◽

Wall Region ◽

Square Cylinder ◽

Mean Velocity ◽

Navier Stokes Equations ◽

Turbulent Vortex Shedding ◽

Model Equations ◽

Good Agreement

ABSTRACTThis paper presents a numerical study on turbulent vortex shedding flows past a square cylinder. The 2D unsteady periodic shedding motion was resolved in the calculation and the superimposed turbulent fluctuations were simulated with a second-order Reynolds-stress closure model. The calculations were carried out by solving numerically the fully elliptic ensemble-averaged Navier-Stokes equations coupled with the turbulence model equations together with the two-layer approach in the treatment of the near-wall region. The performance of the computations was evaluated by comparing the numerical results with data from available experiments. Results indicate that the present study gives good agreement in the shedding frequency and mean drag as well as in some phase profiles of the mean velocity.

Download Full-text

Turbulent vortex streets and the entrainment mechanism of the turbulent wake

Journal of Fluid Mechanics ◽

10.1017/s0022112074000553 ◽

1974 ◽

Vol 62 (1) ◽

pp. 11-31 ◽

Cited By ~ 58

Author(s):

Demosthenes D. Papailiou ◽

Paul S. Lykoudis

Keyword(s):

Vortex Shedding ◽

Reynolds Numbers ◽

Turbulent Wake ◽

Vortex Street ◽

Experimental Measurements ◽

Formation Region ◽

Turbulent Vortex ◽

Geometrical Characteristics ◽

Vortex Streets ◽

Longitudinal Distance

The results of an experimental investigation of a turbulent vortex street in the range 103 [lsim ] Re [lsim ] 2 × 104 are presented. The vortex street was created by the motion of a circular cylinder in a motionless fluid (mercury). Photographs obtained showed that the turbulent street, created by the vortex shedding behind the cylinder, persisted at longer downstream distances and higher Reynolds numbers than previously reported in the literature. A theory was developed to account for the experimental measurements pertaining to the change of the geometrical characteristics, h (distance between the two rows of vortices) and α (longitudinal distance between two consecutive vortices on the same row), of the street in the downstream direction. The implications of the structure of the vortex street on the entrainment mechanism of the turbulent wake are discussed. Some observations of the flow in the formation region of the vortices are discussed in relation to existing work.

Download Full-text

A NUMERICAL STUDY OF VORTEX SHEDDING AFTER MULTIPLE CYLINDERS

Asian and Pacific Coasts 2009 ◽

10.1142/9789814287951_0153 ◽

2009 ◽

Author(s):

ZHIYONG HAO ◽

XIKUN WANG ◽

SOON KEAT TAN

Keyword(s):

Vortex Shedding ◽

Numerical Study

Download Full-text