FSI modeling of a propulsion system based on compliant hydrofoils in a tandem configuration

Fluid–structure interaction (FSI) analysis of the Mirage Drive, a bioinspired propulsion system utilizing compliant hydrofoils designed and built by Hobie Cat Co, is performed. The current work continues a recent experimental and numerical FSI study of a single compliant hydrofoil, and presents, for the first time, full-scale FSI simulation of two compliant hydrofoils in a tandem configuration. The underlying computational challenges are addressed by means of core FSI methods (i.e., the ALE–VMS formulation, weakly enforced no-slip boundary conditions, the sliding-interface technique, and a quasi-direct coupling strategy), as well as special FSI techniques developed for this problem class. Details of the computational framework are discussed, and the computational results are validated using data from field tests, which are also described in the manuscript.