Comparisons of two representative methods classified as immersed boundary and domain methods

Immersed methods have proven to be powerful numerical measures to simulate intricate fluid-structure interactions using non-conforming meshes. And they can be classified into immersed boundary methods and immersed domain methods based on the utilization of fictitious fluid around the interface or over the entire solid domain. Their performances are compared in light of several common problems for immersed methods, and two representative methods are employed by immersed boundary-lattice Boltzmann method with smoothed point interpolation method (IBLBM-SPIM) and immersed smoothed point interpolation method (IS-PIM). Numerical tests show that IS-PIM allows a fairly independent mesh size for each domain of fluid and solid, and achieves a smooth solid response; IBLBM-SPIM can ensure numerical stability in a large range of density ratio between solid and fluid by setting a proper time step to alleviate the added mass effect, and has a direct influence on the deformation and motion of solids. The present study also gives some enlightening thoughts on developing novel methods to deal with different FSI problems.