The problem of fluid-structure interactions (FSI) is encountered in many scientific and engineering applications, such as the aero-elastic response of airplane wings, wind-excited vibration of turbine blades, blood flows through heart valves, and the design of underwater vehicles. While analytical solutions for FSI problems are limited due to the complex nature of the problem, experiments and numerical simulations have been extensively conducted to investigate the flow physics associated with FSI. Numerical simulations are often employed to provide flow details in time and three-dimensional space and reveal the underlying flow dynamics. Because the flow fields are strongly affected by the presence of structures and the structure motions are coupled with the fluid flows, FSI problems pose considerable challenges to simulations in terms of numerical methods and computational cost.
Using the immersed boundary (IB) method, we have developed a numerical capability to simulate the interactions between fluid flows and rigid/deformable bodies. The IB method uses Cartesian grids which are not necessarily body-fitted and do not deform with structure motion, which makes it beneficial to simulate moving structures and structures with complex geometry. Please refer to land-air-sea interaction and hydropower for examples.
In our simulations of FSI, the fluid-solid interfaces are updated at every time step in the simulation. Motions of solid bodies are dynamically coupled with fluid flows by calculating the fluid forces exerted on the solid bodies. A finite-element method is used to solve the deformation of solid bodies. The movies below show two examples on the interaction between flow and deformable structures. Other examples on FSI can be found in renewable energy, biological flows and biomimetics, vegetation flow, and hydropower.
- He, S., Yang, Z., Sotiropoulos, F. & Shen, L. (2021), "Numerical simulation of interaction between multiphase flows and thin flexible structures," Journal of Computational Physics, in press.
- Calderer, A., Guo, X., Shen, L. & Sotiropoulos, F. (2018), “Fluid-structure interaction simulation of floating structures interacting with complex, large-scale ocean waves and atmospheric turbulence with application to floating offshore wind turbines,” Journal of Computational Physics, Vol. 355, pp. 144-175.
- Cui, Z., Yang, Z., Jiang, H., Huang, W. & Shen, L. (2017), “A sharp interface immersed boundary method for simulating incompressible flows with arbitrarily deforming smooth boundaries,” International Journal of Computational Methods, Vol. 14, No. 2, 1750080.
- He, S., Yang, Z. & Shen, L. (2017), "Numerical simulation of interactions among air, water, and rigid/flexible solid bodies," Proceedings of 10th International Workshop on Ship and Marine Hydrodynamics, Keelung, Taiwan.
- Calderer, A., Guo, X., Shen, L. & Sotiropoulos, F. (2014), “Coupled fluid-structure interaction simulation of floating offshore wind turbines and waves: a large eddy simulation approach,” Journal of Physics, Vol. 524, Proceedings of The Science of Making Torque from Wind.