Jean-François Sigrist

• Délégation Générale pour l'Armement

This chapter provides an overview of methods for calculating the vibro‐acoustics of ships. Now well proven in engineering, they can be implemented in general numerical simulation tools, which are used daily by design engineers. The chapter discusses the hypotheses concerning their use, the associated mathematical formulations and certain techniques...

A semi-analytical model for a naval shock problem is proposed in this paper. It is applied to calculate the signals and response spectra which characterize the dynamic response of submarine hulls bearing equipment, when the latter is subjected to a pressure wave triggered by a far-field underwater explosion. It is also used to compare the configura...

Cet ouvrage propose une vue d’ensemble des méthodes de simulation numérique des interactions fluide-structure (IFS) pour des applications en génie maritime.Interactions fluide-structure détaille une large variété de modélisations (numériques, semi-analytiques, empiriques), de méthodes de calcul (éléments finis, éléments de frontière, volumes finis)...

Cet ouvrage propose une vue d’ensemble des méthodes de simulation numérique des interactions fluide-structure (IFS) pour des applications en génie maritime.Interactions fluide-structure détaille une large variété de modélisations (numériques, semi-analytiques, empiriques), de méthodes de calcul (éléments finis, éléments de frontière, volumes finis)...

Numerical simulation has become a tool for understanding and predicting with increasing precision many phenomena occurring in the oceans and atmosphere. This chapter provides an overview, ranging from weather forecasting to climate change modeling. Wind speed, air temperature and pressure, atmospheric humidity is the quantities that weather forecas...

Large‐scale access to mechanical energy has given humanity a new power to control and shape the world by pushing the limits of its physical constraints. The energy sector, strategically contributing to the humans, makes extensive use of numerical simulation in order to: optimize the operation of energy production machines; demonstrate the expected...

The history of the Universe is that of a long aggregation of its matter that sees the formation of the first stars and galaxies and other celestial bodies. The gravitational field plays an important role in the formation of black holes, and in order to understand the dynamics of these structures observed in the Universe and certain complex phenomen...

The First and Second World Wars accelerated the development of aeronautical and naval technology. Without claiming to be exhaustive, as the subjects are so varied, this chapter proposes some examples where numerical simulation accompanies engineering studies in shipbuilding and aeronautics and where it contributes to improving performance. Numerica...

The productive capacity of each country depends on soil quality, the area available or used for agriculture, the climatic conditions to which it is exposed and the available cultivation techniques and agricultural practices developed there. All over the world, some farmers are trying to renew agricultural practices. Numerical simulation makes it po...

Understanding individuals or societies using data helps to predict individual or collective choices. This chapter provides some examples of models that can be applied to certain social issues or contribute to personal or collective decision‐making. A social network on the Internet lends itself quite naturally to a mathematical description according...

Many mathematical models developed in fundamental sciences, such as soil or fluid mechanics, make it possible to accurately represent certain situations encountered in the human body. Red blood cells are rich in hemoglobin, the protein that can carry oxygen or carbon dioxide, while white blood cells are responsible for the body's defense. Modeling...

Complementing the mathematical language of equations, data science contributes to the production of knowledge about a system, with data allowing, in the same way as equations, the construction of predictive mathematical models. Data‐based modeling is at the heart of Big Data, which involves using data from various sources to identify relationships...

Digital simulation is flourishing in the 21st Century in a global context and its mastery is accompanied by high stakes of scientific and economic supremacy. Developing a digital simulation tool consists in putting end‐to‐end lines of code expressed in a computer programming language, often known only to developers! Among others, the English mathem...

Sneaking into the psychology of the characters with subtlety, in her novel Birth of a Bridge, Maylis de Kerangal paints a portrait of women and men accustomed to the mud of the construction sites and the adventures, technical or human, of a civil engineering project. Before carrying out the “lifesized fulfilment”, engineers build confidence in calc...

Written in the second half of the 19th Century, the novels by French writer Jules Verne recall the scientific and technological progress of his century. Published in 1870, Twenty Thousand Leagues Under the Sea is one of his most translated works. This chapter discusses numerical simulation, which is based on the premise that it is possible to repor...

Ces travaux présentent la validation d'une boucle de calculs fortement couplés fluide-structure à l'aide des logiciels commerciaux de CFD (Starccm+) et de CSD (Abaqus) des déformations d'un profil composite sous chargement hydrodynamique. Le cas de validation envisagé ici est un NACA0009 développé initialement par l'Australian Maritime College (AMC...

The objective of this paper is to investigate the fluid structure interaction of a 3D NACA0009 composite hydrofoil in steady and unsteady flows. This hydrofoil set up, which was originally developed experimentally by the Australian Maritime College (AMC), is clamped at the root and free at the tip section, and was designed to behave like a marine p...

This work deals with the dynamic analysis of an immersed circular cylinder, stiffened at its extremities, with a membrane-like behavior subjected to an axial force and fluid-structure interaction loadings. The membrane density and the fluid density are of the same order, hence the added mass effect is significant and the physical coupling is strong...

Fluid-Structure Interaction: An Introduction to Finite Element Coupling fulfils the need for an introductive approach to the general concepts of Finite and Boundary Element Methods for FSI, from the mathematical formulation to the physical interpretation of numerical simulations. Based on the author's experience in developing numerical codes for in...

This chapter presents various coupled formulations when compressibility and gravity are present in the fluid modelling. Symmetric or non-symmetric formulations are described and illustrated on simple configurations suited for analytical solutions. The numerical technique of coupling together finite elements describing the solid part of the system a...

This chapter studies the vibrations of an elastic structure containing an incompressible and non-viscous fluid. As far as the discretised formulation of the problem is concerned, either using a finite element or a boundary element method, it can be described in terms of the sole nodal vector of the structure acceleration, acting on the so-called ad...

This chapter provides an overview of some methods which may be used by the engineering community for dealing with forced dynamical problems in mechanical systems involving fluid–structure interaction (FSI). The computation of the response of the system under dynamic loading can be carried out with direct methods, that is, by solving a finite elemen...

This chapter focuses on wave equations arising for fluids on account of compressibility or gravity effects. Wave equations derive from the mass and momentum equations, which constitute the Navier–Stokes model, when considering the small transformations of perfect fluids initially at rest. Pressure and displacement-based formulations of the wave equ...

This chapter presents an introduction to fluid–structure interaction (FSI) by providing a short overview of some analytical models and numerical methods. The analytical models focus on the description of the so-called inertial effect on the one hand and of vibro-acoustic coupling on the other hand. The principles of a coupled simulation are also co...

This chapter deals with the discretisation of the partial differential equations accounting for the linear vibrations of elastic structures by using the finite element method (FEM). Weighted integral formulation, geometry discretisation, polynomial approximation, definition of elementary and global matrices: the various steps of the FEM are recalle...

La caractérisation de la signature acoustique et vibratoire de structures en mer en présence d'incertitudes est considérée avec intérêt dans l'industrie marine. La dimension stochastique de tels pro-blèmes pouvant être grande, nous proposons une méthode basée sur le mariage efficace de techniques de réduction de modèle et d'approche par échantillon...

The present paper deals with the dynamic analysis of a tube bundle with Fluid Structure Interaction (FSI) modeling using a structural acoustic homogenized method. Such a coupled problem leads to many degrees of freedom [a system of very large matrices] to compute tube displacements and pressure in the acoustic domain, it is therefore irrelevant to...

In this work we are interested in the vibration and in the acoustic field generated by a structure submerged in fluid, under a turbulent boundary layer flow. The response of the structure is driven by the low wavenumber behaviour, for a small Mach number. This work aims at providing better means of predicting the noise radiated in such setups, main...

In this work we are interested in the vibration and in the acoustic field generated by a structure submerged in fluid, under a turbulent boundary layer flow. The response of the structure is driven by the low wavenumber behaviour, for a small Mach number. This work aims at providing better means of predicting the noise radiated in such setups, main...

It is well known that a fluid may strongly influence the dynamic behaviour of a structure. Many different physical phenomena may take place, depending on the conditions: fluid flow, fluid at rest, small or high displacements of the structure. Inertial effects can take place, with lower vibration frequencies, dissipative effects also, with damping,...

The transient dynamics of evacuated and fluid-filled circular elastic shells, submerged in an infinite fluid medium and subjected to an external weak shock wave, is considered in this paper. This circular shell/acoustic medium interaction problem has already been tackled with simplified thin shell models, based on the Love-Kirchhoff hypotheses for...

We consider a number of problems of non-stationary fluid-structure interaction, specifically that of weak shock waves and fluid-contacting thin-walled structures, and employ analytical and semi-analytical solutions to simulate the interaction. We demonstrate that such solutions can be a very efficient and accurate analysis tool for certain geometri...

The present paper deals with numerical developments performed in the finite element code ANSYS in order to implement coupled fluid structure formulations using symmetric matrices. The so-called (u, p, φ) formulation with mass and stiffness coupling is developed in the ANSYS code, enhancing the modeling possibilities of the existing fluid elements....

This paper deals with fluid forces induced by an oscillating rigid circular cylinder in a fluid initially at rest. The amplitude of the imposed movement is assumed sufficiently small so that no wake is formed. The objective of the present paper is to review different theoretical methods to evaluate fluid forces. A wide variety of conditions is cons...

The present paper deals with the study of fluid forces in an incompressible viscous fluid at rest around an accelerated rigid circular cylinder. The movement subjected to the cylinder is an impulsive motion represented by a only one period of a sinusoidal acceleration. After this period, the cylinder is stopped. This study is performed for small di...

The study of a interaction fluid-structure problem requires the calculation of fluid forces acting on moving boundaries. Since the first studies carried out by Stokes, a lot of work has been performed to derive various expressions of fluid forces, in particular for the case of simple geometry, such as infinite planes, spheres or circular cylinders....

Nous nous intéressons dans cette thèse à la modélisation et la simulation numérique d'un problème couplé fluide/structure non linéaire avec surface libre fluide. Nous définissons un cas générique d'étude pour lequel nous formulons un problème linéaire (problème aux valeurs propres du système couplé) et un problème non linéaire (problème d'évolution...

The present paper is related to the study of a generic linear coupled fluid/structure problem, in which an elastic beam is coupled with an inviscid fluid, with or without sloshing effects. A previous study [18] focussed on added mass effects; the present study is devoted to the coupling effects between fluid sloshing modes and structure with fluid...

This paper is related to the study of a nuclear propulsion reactor prototype for the French Navy. This prototype is built on ground and is to be dimensioned toward seismic loading. The dynamic analysis takes the coupled fluid structure analysis into account. The basic fluid models used by design engineers are inviscid incompressible or compressible...

Une préoccupation constante de tout industriel est la maîtrise des marges de dimensionnement de ses structures. Le recours aux techniques de calcul scientifique permet en phase de conception détaillée un dimensionnement au plus juste des structures, tout en respectant les différentes contraintes de conception (exigences fonctionnelles, conditions d...

Une préoccupation constante de tout industriel est la maîtrise des marges de dimensionnement de ses structures. Le recours aux techniques de calcul scientifique permet en phase de conception détaillée un dimensionnement au plus juste des structures, tout en respectant les différentes contraintes de conception (exigences fonctionnelles, conditions d...