Fluid-structure interaction

Fluid-Structure Interactions (FSI) is the chapter of Mechanics devoted to describing the movements of structures immersed in a fluid that is itself in motion, and more specifically to determining how the fluid modifies the behavior of the structures.

We are therefore at the frontier between structural dynamics and fluid dynamics. This implies that the field of IFS borrows from both disciplines:

• as things are seen from the "structural side", it fits into the general framework of structural dynamics;

• but of course we also have to consider fluid flows, and in particular some of their characteristics in the vicinity of walls.

In fact, the specific aspect of IFS is to describe how the movements of a wall modify a flow and how this is reflected in the field of forces exerted on this wall.

This last definition covers a vast physical field with many industrial applications.

We can apply the traditional classification of structural dynamics which distinguishes schematically :

• Problems involving small movements, which fall within the scope of vibration theory. They are often modeled linearly or pseudo-linearly and described in the frequency domain. The motions involved can be highly complex, with probabilistic representations.

• Problems involving the large-scale movement of structures involving strong geometric and material non-linearities. These problems are generally described in the time domain, due to their often transient nature and the relative simplicity of the motions involved. Taking non-linearities into account in calculations also requires this type of description.

Two types of IFS presentation are then possible:

• Either the presentation of the general case of large movements, very focused on numerical resolution methods. Small movements are a special case, but it's quite difficult to understand their physical principles and associated engineering methods.

• In other words, a much more physical presentation of the case of small movements within the framework of linear vibration theory, with extrapolation necessarily limited to non-linear cases.

This is the second approach we have chosen.

Now that we've opted for the presentation method, let's define its contours. A complete presentation...