Numerical methods of coupled fluid/structure calculation

Phenomena linked to fluid/structure mechanical coupling occur, to varying degrees of importance, in any structure in contact with a fluid. This type of multiphysical coupling is encountered in many industrial situations, and the influence it can have on the dynamic behavior of mechanical systems is often significant. Taking into account the effects of fluid/structure coupling therefore becomes a key issue in structural design, particularly in view of the safety requirements associated with their design. The ongoing development of numerical computation techniques and the ever-increasing computing capacity of machines make it possible to implement complex numerical simulations, involving a wide range of couplings. The aim of this article is to provide an introduction to the general numerical methods available to engineers for simulating fluid/structure coupling problems. The variety of physical situations and problems posed by fluid/structure coupling is such that it is difficult to establish a general classification of numerical methods. In this presentation, however, a distinction is made between two broad classes of coupled problems, depending on whether the fluid is stagnant or flowing. The numerical methods presented and discussed in this introductory paper correspond to computational techniques that can be implemented with general-purpose computational tools. In this context, the article does not claim to be exhaustive, as there are as many numerical methods as there are physical situations in fluid/structure coupling. The implementation of a numerical calculation requires a good understanding of the mechanisms governing the physics of the problem under study; in this context, reading general works dedicated to the description and understanding of the fundamental mechanics of fluid/structure coupling is a relevant prerequisite to the presentation of calculation methods. The present article can be seen in its spirit as a complement to the article "Interaction fluide/structure vibrante" proposed by René-Jean Gibert in Techniques de l'Ingénieur [AF 5 250] . The presentation is divided into two sections: the first offers a few basic reminders of the fluid/structure coupling problem; the second develops the principles of coupling methods for a stagnant fluid. A second article, to be published shortly, will address the principles of coupling methods for flowing fluids. We will also take the opportunity to place these methods in the context of their industrial use.