Wagner Gonçalves Pinto

IFP Energies nouvelles

New data and review of the spanwise coherence length is provided for flows over cylinders of different cross-sections: circular of diameter d, and rectangular of sectional aspect ratios (breadth (b) to height (d) ratio AR = b/d) of 1, 2 and 3. In the present measurements, the body has both d and spanwise length of 70d fixed, and the Reynolds number...

Reproducibility of a deep-learning fully convolutional neural network is evaluated by training several times the same network on identical conditions (database, hyperparameters, and hardware) with nondeterministic graphics processing unit operations. The network is trained to model three typical time–space-evolving physical systems in two dimension...

Accurate modeling of boundary conditions is crucial in computational physics. The ever increasing use of neural networks as surrogates for physics-related problems calls for an improved understanding of boundary condition treatment, and its influence on the network accuracy. In this paper, several strategies to impose boundary conditions (namely pa...

Accurate modeling of boundary conditions is crucial in computational physics. The ever increasing use of neural networks as surrogates for physics-related problems calls for an improved understanding of boundary condition treatment, and its influence on the network accuracy. In this paper, several strategies to impose boundary conditions (namely pa...

Localization and quantification of noise sources is an important scientific and industrial problem, the use of phased arrays of microphones being the standard techniques in many applications. Non-physical artifacts appears on the output due to the nature of the method, thus, a supplementary step known as deconvolution is often performed. The use of...

The Reynolds number for the onset of flow unsteadiness is determined for several canonical geometries (triangles, rectangles, ellipses and lozenges) at different sectional breadth (L) to height (d) ratios (aspect ratio AR=L∕d), for more than 70 shapes. The flow is modeled using a direct Navier–Stokes incompressible two-dimensional solver and the sh...

Accurate modeling of boundary conditions is crucial in computational physics. The ever increasing use of neural networks as surrogates for physics-related problems calls for an improved understanding of boundary condition treatment, and its influence on the network accuracy. In this paper, several strategies to impose boundary conditions (namely pa...

Reproducibility of a deep-learning fully convolutional neural network is evaluated by training several times the same network on identical conditions (database, hyperparameters, hardware) with non-deterministic Graphics Processings Unit (GPU) operations. The propagation of two-dimensional acoustic waves, typical of time-space evolving physical syst...

The tonal noise generated by the flow over elongated cylinders is measured using microphones in the anechoic wind tunnel BETI of Institut Pprime. The effect of the length to diameter ratio of the cylinder is assessed by varying the diameter from 6 mm to 20 mm within the constant width (750mm), open jet, test section. The velocity is varied from 10...

In order to interpret recent results of shape optimization for the aeolian tone problem in 2D, laminar flows, the Reynolds number corresponding to the onset of unsteadiness in a flow over a bluff body is estimated for a set of shapes : five canonical shapes (the ellipse, the rectangle, the losenge and two triangles) are studied, as well as the infl...

The coherence length is a key ingredient in the efficiency of the aeolian tone generated by the flow over a bluff body, and is often used to extrapolate noise simulations of a short segment of cylinder for comparison with measurements using longer bodies. In the present study, the influence of the cylinder cross-section on the coherence length is s...

A shape optimization for tonal noise generated aerodynamically at low Mach number is performed for a cylinder with polygonal cross-section. Acoustic quantities are derived from a hybrid analytical formula, with aeroacoustic sources obtained from the incompressible solution of the direct Navier-Stokes equations in 2D at Re = 150; the solid domain is...

The influence of the shape on the sound emission of cylindrical bluff-bodies is studied. Simulations are performed in two-dimensions (2D) at low-Reynolds number (Re=20-200), with the incompressible direct Navier-Stokes (DNS) solver incompact3D, using the Immersed Boundary Method (IBM) formalism; the acoustic emission is evaluated by a single formul...

The influence of the geometry of prismatic bodies on their aerodynamic sound emission is studied. Curle's formalism links the noise level to lift fluctuation and the spanwise organization of the flow coherent structures. Here, the acoustic field is measured using a set of microphones, and the flow spanwise coherence length is estimated from hot-wir...

Influence of the cross section on airframe noise is investigated numerically in 2D at low Reynolds number (Re = 150) by a direct Navier-Stokes (DNS) solver and an acoustic power formulation derived from an hybrid acoustic analogy. Flows around different canonical geometries (rectangle, triangle, ellipse and lozenge) and of different breadth-to-height...

A shape optimization procedure is presented. It is dedicated to the noise generated by obstacle flows. The cost function is the acoustic power efficiency, which is derived directly from the fluctuations of the aerodynamic force by a single formula from the hypothesis of tonal noise. The force is estimated from the direct solution of the 2D incompre...

Shape optimisation for airframe noise is performed for a cylinder with polygonal crosssection. Acoustic quantities are derived from a hybrid approach, alimented by the incompressible solution of the direct Navier-Stokes equations in 2D; solid domain is defined by a Immersed Boundary Method. Optimisation is done with the Particle Swarm Optimisation...

Une procédure d’optimisation de forme est présentée. Elle est dédiée au bruit généré par les écoulements d’obstacle. La fonctionnelle coût est la puissance acoustique, qui est déduite directement des fluctuations d’effort aérodynamiques par une formule analytique en hypothèse de bruit tonal. Ces derniers sont estimés à partir de la résolution numér...

La problématique du sifflement généré par l’écoulement sur un rétroviseur automobile est abordée par une approche numérique. La modélisation consiste en la sélection d’un profil géométrique pour lequel la dynamique est majoritairement bidimensionnelle. Également, le choix d’un régime incompressible à bas nombre de Reynolds représente bien les aspec...

The pickups correspond to an important category of commercial vehicle once they combine passenger and cargo transport. The presence of an open trunk is responsible for a unique flow topology within a natural great interest for manufacturer's research and that is gradually being more discussed on academic articles. This work presents a numerical and...

This paper is dedicated to the uncertainty analysis of the dynamic response of a simple supported rotor system composed by a horizontal flexible shaft, one rigid disc, and one additional ball bearing. A mathematical model of the rotor is derived from the Lagrange’s equation by using the Rayleigh-Ritz method. Some simplifications are adopted in orde...