| Flow-structure interaction problems are ubiquitous in nature. Examples in daily life are flags flapping in the air, fish swimming in the water and voice production in the human larynx, etc. These problems typically involve highly irregular geometries with large displacements. In addition, the fluid-solid coupling is inherently nonlinear and involves the unsteady interplay among the hydrodynamic, elastic, damping, and inertial forces. Although the FSI has been an active area for many years, it is still a significant challenge to achieve both accuracy and efficiency when modeling these problems computationally. In this seminar, a modified penalty approach will be introduced into the flow-structure interaction solver that combines an immersed boundary method (IBM) and a multi-block lattice Boltzmann method (LBM) to model an incompressible flow and elastic boundaries with finite mass. The effect of the solid structure is handled by the IBM in which the stress exerted by the structure on the fluid is spread onto the collocated grid points near the boundary. The fluid motion is obtained by solving the discrete lattice Boltzmann equation. The inertial force of the thin solid structure is incorporated by connecting this structure through virtual springs to a ghost structure with the equivalent mass. This treatment ameliorates the numerical instability issue encountered in this type of problem. Thanks to the superior efficiency of the IBM and LBM, the overall method is extremely fast for a class of flow-structure interaction problems. As applications of the present method, the interaction of flexible-rigid bodies and three side-by-side coupled filaments in flow are presented to understand fluid-structure interaction and biology behavior of aquatic animals |