Improving the CBS-based partitioned semi-implicit coupling algorithm for fluid-structure interaction

We detail in this work 2 simple but effective alternatives to improve the characteristic-based split-based partitioned semi-implicit coupling algorithm for fluid-structure interaction. The basic idea lies in introducing the end-of-step velocity into the implicit stages of the 2 algorithms integrating different splits. The algorithm built upon the second-order pressure split is further stabilized via the pressure gradient projection with particular emphasis on the extremely low mass ratio. The smoothed finite element method is exploited for spatial discretization of fluid and solid equations. Even without any accelerators, both the semi-implicit solvers incorporating fixed-point iterations engender visible improvements versus the previously published data for several benchmarks.