Entity

Time filter

Source Type

United Kingdom

Neves M.A.S.,LabOceano | Vivanco J.E.M.,LabOceano | Rodriguez C.A.,COPPE UFRJ
Fluid Mechanics and its Applications | Year: 2011

The present paper employs nonlinear dynamics tools in order to investigate the dynamical characteristics governing the complex coupling of the heave, roll and pitch modes in head seas at some regions of the numerical stability map of a fishing vessel. Bifurcation diagrams and Poincaré mappings are computed and employed to investigate the appearance of multistability and chaos associated with increased values of the selected control parameter, the wave amplitude. The connection between these nonlinear characteristics and the coupled nature of the mathematical model are analyzed. Lyapunov exponents corresponding to the three coupled models are computed. © Springer Science+Business Media B.V. 2011.


Wanderley J.B.V.,LabOceano | Sphaier S.H.,LabOceano | Levi C.,LabOceano
Journal of Offshore Mechanics and Arctic Engineering | Year: 2011

The hysteresis effect on the vortex induced vibration (VIV) on a circular cylinder is investigated by the numerical solution of the two-dimensional Reynolds averaged Navier-Stokes equations. An upwind and total variation diminishing (TVD) conservative scheme is used to solve the governing equations written in curvilinear coordinates and the k-e{open} turbulence model is used to simulate the turbulent flow in the wake of the body. The cylinder is supported by a spring and a damper and free to vibrate in the transverse direction. In previous work, numerical results for the amplitude of oscillation and vortex shedding frequency were compared to experimental data obtained from the literature to validate the code for VIV simulations. In the present work, results of practical interest are presented for the power absorbed by the system, phase angle, amplitude, frequency, and lift coefficient. The numerical results indicate that the hysteresis effect is observed only when the frequency of vortex shedding gets closer to the natural frequency of the structure in air. © 2012 American Society of Mechanical Engineers.


Wanderley J.B.V.,Federal University of Rio de Janeiro | Soares L.F.,Federal University of Rio de Janeiro | Vitola M.,LabOceano | Sphaier S.H.,LabOceano | Levi C.,LabOceano
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2011

The vortex induced vibration (VIV) on a circular cylinder with low mass-damping parameter and low Reynolds number is investigated numerically as basis for applications on dynamics of risers used in the offshore oil and gas industry and as a first step before tackling the harder high Reynolds number problem. The cylinder is supported by a spring and a damper and free to vibrate in the transverse direction. The numerical solution of the Reynolds average Navier-Stokes equations written in curvilinear coordinates is obtained using an upwind and Total Variation Diminishing conservative scheme and the k-ε turbulence model is used to simulate the turbulent flow in the wake of the body. Results were obtained for the phase angle, response amplitude, frequency, and lift coefficient for a variation of reduced velocity from 2 to 12 and three different proportional variations of Reynolds number, 2000-6000, 2000-12000, and 2000-24000. The numerical results indicate the strong effect of the Reynolds number range on the response amplitude, lift coefficient, and frequency of oscillation for a low mass-damping parameter. Copyright © 2011 by ASME.


Soares L.F.N.,LabOceano | Wanderley J.B.V.,LabOceano | Vitola M.,LabOceano | Sphaier S.H.,LabOceano | Levi C.,LabOceano
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2010

The vortex induced vibration (VIV) on a circular cylinder is investigated by the numerical solution of the two-dimensional Reynolds average Navier-Stokes equations. An upwind and Total Variation Diminishing (TVD) conservative scheme is used to solve the governing equations written in curvilinear coordinates and the k-e turbulence model is used to simulate the turbulent flow in the wake of the body. The cylinder is supported by a spring and a damper and free to vibrate in the transverse direction. Results are obtained for the phase angle, amplitude, and frequency for an elastically mounted rigid cylinder subjected to vortex shedding and support motion. The numerical results showed the strong influence of the support motion on the response amplitude. This kind of scenario is found in the attachment between platform and riser. The motion of platforms on the ocean free surface can cause this kind of excitation and amplify the vortex induced vibration response amplitude of risers. Copyright © 2010 by ASME.

Discover hidden collaborations