MS17.3: Fluid-Structure Interaction

Bridge structures and piers are subjected to severe environmental conditions, such as surges and icing, which can significantly impact their durability and performance. In the present work, we use a surface with a modified wall contact angle named "hybrid wettability coatings," which combines both hydrophilic and superhydrophobic properties. The results are compared with those on superhydrophobic (contact angle of 160°), hydrophobic (contact angle of 80°), and superhydrophilic (contact angle of 0°) surfaces. The results show that a hybrid surface significantly decreases the frequency of vortex shedding, thereby postponing the resonance phenomenon. Furthermore, the interaction between superhydrophobicity and hydrophilicity in the hybrid surface, based on changes in surface tension force, can alter the effects of ice adhesion. Therefore, hybrid wettability coatings can be used as a new surface for enhanced pier durability as well as anti-icing applications.

The dynamical behavior of cylindrical offshore structures, which are excited by nonlinear water waves, is investigated. The incoming water waves are calculated using specific solutions of the nonlinear Schrödinger equation, which can be seen as prototypes of extreme water waves. The corresponding fluid-structure interaction with the cylindrical offshore structures is calculated using linear and nonlinear potential flow theory. By comparing the corresponding results, the nonlinear effects that occur in the fluid-structure interaction are analyzed.

The piezoelectric energy harvesting from the galloping of a rigid prism is numerically investigated. The prism is mounted on a bimorph piezoelectric cantilevered beam and on a nonlinear spring whereas the aerodynamic force is computed using the classical quasi-steady approach. The results for four configurations are presented in this article: two bistable nonlinear energy harvester, a monostable nonlinear energy harvester and a linear energy harvester. Among other aspects, results show evidences of chaotic responses for bistable configurations.

The alternating frequency-time harmonic balance method (AFT-HBM) is proposed to solve a nonlinear, coupled fluid-structure problem. The method is explained, and its capabilities are demonstrated for specific system parameters. Excellent agreement between the AFT-HBM and direct numerical integration is achieved for the steady-state solution of the system. Future work on solving coupled fluid-structure problems in the frequency-domain is proposed with the aim of studying more complex systems.