An algorithm for permanent fluid-structure interaction in explicit transient dynamics Original Research Article

is paper presents the strategies and models adopted in the PLEXIS-3C computer code for the description of interactions of the permanent type between fluids and structures in fast transient dynamic problems. A careful analysis of geometrical issues and the use of a method based on Lagrange multipliers for the treatment of essential boundary conditions lead to a scheme which appears to be both general and robust, while remaining reasonably simple. The method is implemented via an algorithm able to deal automatically with situations of large geometrical complexity, such as those encountered with box-like structures—multiple interactions, structural bifurcations or even arbitrary structural intersections, submerged structural edges, etc.—in the presence of large structural displacements, rotations and deformations. The algorithm turns out to be efficient and dramatically reduces the amount of information that has to be supplied in order to describe a given interaction, compared with the algorithms used in previous PLEXIS-3C implementations. As a consequence, the time and effort needed for input preparation in large and complex, realistic simulations, is substantially reduced and the possibility for human errors in this phase is almost eliminated. Several examples show the application of the method to problems of practical interest.