The interaction of fluids with mechanical systems, also known as fluid-structure interaction, is a multi-physics phenomenon which can be observed in a vast variety of scientific problems, industrial applications, and everyday life. Think, for instance, of the motion and deformation of the flexible rotor blades of a wind turbine, the impact of water waves against embankments, or the motion of the heart valves in the human body – the characteristics of such examples are crucially determined by the interaction between the mechanical structures and fluids. Due to the complexity, analytical treatment is usually not possible and experimental approaches are often either expensive or limited in scope. Therefore, the development of computational methods for efficient modeling and simulation of fluid-structure interaction problems is of significant importance from both the scientific as well as the industrial perspective. Based on the coupling of flexible multibody systems with particle-based fluid mechanics, this work describes an unconventional, but promising numerical approach to fluid-structure interaction, covering everything from an introduction to the respective fields, to the underlying theory, the coupling strategy, and implementation details.