Juan Wanderley - Academia.edu (original) (raw)

Papers by Juan Wanderley

Springer eBooks, 2001

APS Division of Fluid Dynamics Meeting Abstracts, Nov 1, 2000

The effects of surface roughness on the vortex-induced vibration (VIV) performances of a circular... more The effects of surface roughness on the vortex-induced vibration (VIV) performances of a circular cylinder were studied numerically. The VIV response amplitude, response frequency, vortex force, vortex phase and vortex shedding flow pattern with different degrees of surface roughness were compared. The numerical results show that the VIV response amplitude decreases with increased surface roughness. For a smooth cylinder and a cylinder with small surface roughness, the VIV response could be divided into three branches: initial branch, upper branch and lower branch. In the initial and upper branches, the vortex shedding flow pattern displays a 2S mode. However, the VIV response produces a 2P mode vortex shedding pattern in the lower branch. For a cylinder with large surface roughness, the VIV response can be divided into only two branches: an initial branch and a lower branch. In the initial branch, the vortex shedding flow pattern displays a 2S mode, but in the lower branch, the pattern changes to the 2P mode. The transition of 2S mode to 2P mode is caused by the abrupt change of the vortex phase between the vortex force and the VIV response.

Ocean Engineering, Dec 1, 2017

Marine systems & ocean technology, Dec 1, 2007

Ocean Engineering, Apr 1, 2012

Journal of Fluid Mechanics, Feb 25, 2001

The leading-edge receptivity to acoustic waves of two-dimensional bodies is investigated using a ... more The leading-edge receptivity to acoustic waves of two-dimensional bodies is investigated using a spatial solution of the Navier–Stokes equations in vorticity/stream function form in general curvilinear coordinates. The free stream is composed of a uniform flow with a superposed periodic velocity fluctuation of small amplitude. The method follows that of Haddad & Corke (1998), in which the solution for the basic flow and the linearized perturbation flow are solved separately. The initial motivation for the work comes from past physical experiments for flat plates with elliptic leading edges, which indicated narrow frequency bands of higher neutral-curve Branch I receptivity. We investigate the same conditions in our simulations, as well as on a parabolic leading edge. The results document the importance of the leading edge, junction between the ellipse and flat plate, and pressure gradient to the receptivity coefficient at Branch I. Comparisons to the past experiments and other numerical simulations showed the influence of the elliptic leading-edge/flat-plate joint as an additional site of receptivity which, along with the leading edge, provides a wavelength selection mechanism which favours certain frequencies through linear superposition.

Journal of the Royal Aeronautical Society, Jun 29, 2023

Accurate and reliable computation of the aerodynamic characteristics of wind turbines is very imp... more Accurate and reliable computation of the aerodynamic characteristics of wind turbines is very important for the development of new efficient designs. The flow around a wind turbine is modeled by a permeable disc (PD), solved through the Unsteady Reynolds-Averaged Navier–Stokes equations (URANS), here named PD/URANS method. The finite volume method and a total variation diminishing (TVD) scheme solve numerically the flow governing equations. The turbulent flow in the wake of the wind turbine is simulated utilising a one-equation turbulence model. The Glauert correction calculation considers a uniform normal force distribution (CT) on the virtual permeable disc applied to the flow, while the axial induction factor is obtained directly from the numerical solution of the URANS equations. The numerical axial induction factor obtained agrees fairly well with Glauert correction, except if the flow behind the turbine is highly unsteady and Reynolds number dependent.

ABSTRACT The vortex-induced vibration on a circular cylinder is investigated by the numerical sol... more ABSTRACT The vortex-induced vibration on a circular cylinder is investigated by the numerical solution of the compressible Navier-Stokes equations in the incompressible Mach number range (Mach<0.3). The agreement with other results obtained for the incompressible Navier-Stokes equations using the semi-implicit projection method is very good while CPU-time for convergence is comparable. In addition, interesting results of practical interest are obtained regarding the vortices generated and carried by the wake of the body. The results provide a good picture of the real physics of the phenomenon showing the Kármán vortex street oscillation of the lift and drag coefficients due to the asymmetric pressure distribution around the cylinder.

Volume 7: CFD and VIV; Offshore Geotechnics, 2011

The vortex-induced vibration (VIV) is a classical problem in ocean engineering. Intensive researc... more The vortex-induced vibration (VIV) is a classical problem in ocean engineering. Intensive research on this field for flow around a circular cylinder has been observed, due to practical application, mainly the design of risers, cables and pipelines with free span. The relevance of this phenomenon is related to the structure failure, consequence of large displacement or fatigue. In the present study the influence of initial condition on the vortex induced vibration (VIV) of a circular cylinder with two degree of freedom is investigated by the numerical solution of the slightly compressible formulation of 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. The k–ε turbulence model is used to simulate the turbulent flow in the wake of the cylinder. Two different initial conditions have been tested, free-stream and continuous reduced velocity increase (us...

Volume 4: Terry Jones Pipeline Technology; Ocean Space Utilization; CFD and VIV Symposium, 2006

The present stage of viscous flow numerical analysis combined with computer technology latest adv... more The present stage of viscous flow numerical analysis combined with computer technology latest advances made viable the mathematical treatment of many robust and complex engineering problems of practical interest. Some numerical problems which solutions would be just unthinkable not more than ten years ago may be now dealt with in a reliable and fairly accurate manner. A truly example of this kind of problem would be the calculation of hydrodynamic loads acting on yawing ships. The solution of such a problem raises practical interest due to applications, for instance, as in the case of stationary FPSO/FSO ships facing sea currents, commonly used in offshore deep-water oil production. In the present solution, the complete incompressible Navier–Stokes (N-S) equations are solved by means of an algorithm that applies the Beam and Warming [1] approximated factorization scheme to simulate the flow around a Wigley’s hull. The numerical code was implemented using Message Passage Interface (M...

The Aeronautical Journal

SummaryA turbulent hot jet is calculated and its entrainment effect is modelled by a line sink wi... more SummaryA turbulent hot jet is calculated and its entrainment effect is modelled by a line sink with the objective of estimating the downwash effect on rectangular lifting surfaces of various aspect ratios. The line sink density is determined by numerical solution of the free shear layer equations with a turbulent kinetic energy model. The ‘incompressible equivalent jet’ concept is verified within the context of practical engineering calculations.

This article presents the conclusions from applying a procedure based on multi-criteria and quali... more This article presents the conclusions from applying a procedure based on multi-criteria and qualitative forecasting methods to hierarchising transport infrastructure investment options with real data; it focusses on the key steps. The procedure can be generalised to urban and regional planning and so on. One important aspect is that it requires multi-segment participation on the basis of participatory planning guidelines, which gives the stakeholders involved greater confidence in the results and in the likelihood they will actually be implemented. The article discusses salient aspects of related theory. A pilot case study was conducted in Brazil as a preliminary to a broader study (later conducted) to validate the procedure and prepare the way for generalisation to other decision-making situations. It was observed that options that obey eco-sustainability and social criteria were preferred, about 24% of the results favouring investments in railways, whether for cargo or passenger t...

Anais do 28º Congresso Internacional de Transporte Aquaviário, Construção Naval e Offshore, 2020

Ocean Engineering, 2018

This work shows a study about the bilge keel and its influence, width and form, on the roll dampi... more This work shows a study about the bilge keel and its influence, width and form, on the roll damping of FPSO sections. A computational code was developed to simulate forced roll oscillation of a middle section of FPSO with different bilge keels types. The computational code calculates the solution of the Navier-Stokes equations in 2D, using the finite volume method and the upwind TVD scheme of Roe-Sweby. The effect of wave radiation is neglected. This work shows how the generated vortices influence the pressure distribution around the middle section of FPSO. The numerical results are compared with experimental results to validate the computational code. New bilge keel configurations were studied to improve the roll damping of FPSO.

Marine Systems & Ocean Technology, 2007

Researchers have spent significant effort to understand the complicated flow around bluff bodies ... more Researchers have spent significant effort to understand the complicated flow around bluff bodies to control or even eliminate the Vortex Induced Vibration (VIV) occurrence. Numerical simulations have been unsuccessful to predict the VIV amplitudes mainly because of the diffusive nature of the numerical methods. The present two-dimensional numerical investigation is a continuation of previous efforts trying to predict correct amplitudes of the VIV oscillations. The upwind TVD Roe-Sweby scheme is used to solve the slightly compressible Reynolds Average Navier-Stokes equations written in general curvilinear coordinates. For comparisons, the SST and the k-e turbulence models are used to simulate the turbulent flow in the wake of a circular cylinder. The numerical results obtained in the present work agree remarkably well with experimental data obtained from the literature. The k-f. turbulence model showed better agreement with experiment than the SST turbulence model.

27º Congresso Internacional de Transporte Aquaviário, Construção Naval e Offshore, 2018