An Integrated High-fidelity Approach for Modeling Flow-Structure Interaction in Biological Propulsion and its Strong Validation

摘要

Biological propulsors (fish fins and insect wings) usually exhibit large and complex deformation during propulsion. This is due to their complex geometries, non-uniform and non-linear material properties and complex interactions with surrounding fluid (water/air). In order to understand the propulsor flexibilities and their hydrodynamic/aerodynamic roles, we propose an integrated high-fidelity numerical method for modeling the flow-structure interactions of biological propulsors. Taking the fish caudal fin as an example, we build a high fidelity structural model, which consists of a series of beams (for fin rays) and a thin shell model supported by those beams. The flexural rigidity of the beams and the shell is reversely determined by a finite element analysis (FEA) through the comparison between the FEA-obtained deformation and the realistic fin kinematics reconstructed from the high-speed videos. And then, a fully coupled flow-structure interaction simulation is carried out to validate the FSI approach. The results show that both the chordwise and spanwise deformation of the caudal fin model obtained in our simulation is consistent with those of the reconstructed fin. Moreover, the thrust and the pressure distribution on the fin surface of the FSI model and the reconstructed model exhibit the same trend. And the wake topology in both models are identical.