# A natural framework for isogeometric fluid-structure interaction based on BEM-shell coupling

## TL;DR

This paper introduces a boundary integral isogeometric framework for fluid-structure interaction involving thin elastic shells and incompressible fluids, featuring three coupling strategies and emphasizing a novel semi-implicit method for robustness.

## Contribution

It presents a new isogeometric boundary integral approach with three coupling strategies, including a novel semi-implicit method for FSI involving thin shells and fluids.

## Key findings

- The semi-implicit coupling method enhances robustness and efficiency.
- The framework effectively models thin shell-fluid interactions.
- The approach leverages boundary representations for accurate simulations.

## Abstract

The interaction between thin structures and incompressible Newtonian fluids is ubiquitous both in nature and in industrial applications. In this paper we present an isogeometric formulation of such problems which exploits a boundary integral formulation of Stokes equations to model the surrounding flow, and a non linear Kirchhoff-Love shell theory to model the elastic behaviour of the structure. We propose three different coupling strategies: a monolithic, fully implicit coupling, a staggered, elasticity driven coupling, and a novel semi-implicit coupling, where the effect of the surrounding flow is incorporated in the non-linear terms of the solid solver through its damping characteristics. The novel semi-implicit approach is then used to demonstrate the power and robustness of our method, which fits ideally in the isogeometric paradigm, by exploiting only the boundary representation (B-Rep) of the thin structure middle surface.