The paper presents several key issues for the development of reliable, accurate and computationally efficient fully-Lagrangian computational methods for reproduction of hydroelastic FSI (Fluid-Structure Interaction) problems. The fully-Lagrangian FSI solvers correspond to projection-based MPS (Moving Particle Semi-implicit) and ISPH (Incompressible Smoothed Particle Hydrodynamics) fluid models coupled with Newtonian MPS/SPH or Hamiltonian MPS/SPH structure models. The mentioned particle-based FSI solvers have been validated through a set of benchmark tests. The key aspects for development of robust and reliable fully-Lagrangian mesh-free FSI solvers are discussed in terms of Newtonian/Hamiltonian structure models, fluid- structure coupling schemes and adaptivity corresponding to multiresolution FSI simulations.
The interactions between fluids and elastic structures have been of substantial importance in ocean engineering (Liu et al., 2014). In specific, in line with advancement of marine technology for application of lightweight elastic materials, the hydroelasticity effects have become more significant, indicating the need for rigorous related studies.
With respect to the advantageous contributions that Lagrangian mesh- free methods or particle methods, e.g. Smoothed Particle Hydrodynamics (SPH; Lucy, 1977; Gingold and Monaghan, 1977), bring about in fluid and structure dynamics (Gotoh and Khayyer, 2018), several studies have been conducted by utilizing these new generation computational methods for hydroelastic Fluid-Structure Interaction (FSI) simulations. In some studies, particle methods have been coupled with other numerical frameworks, e.g. coupled SPH-FEM (e.g. Fourey et al., 2017). On the other hand, integrated fully-Lagrangian mesh-free methods (e.g. Antoci et al., 2007; Oger et al., 2010) provide higher levels of computational flexibility as well as potentially more consistent imposition of fluid-structure interface boundary conditions.
With respect to superiorities of semi-implicit projection-based particle methods, e.g. Moving Particle Semi-implicit (MPS; Koshizuka and Oka, 1996) and Incompressible SPH (ISPH; Shao and Lo, 2003) with respect to explicit ones, in providing higher order accuracy in pressure calculation and volume conservation (Gotoh and Khayyer, 2018), coupling between projection-based particle methods with MPS/SPHbased structure models would lead to robust and physically/mathematically consistent frameworks for reproduction of incompressible fluid-elastic structures interactions. In this regard, Hwang et al. (2014) coupled a projection-based MPS fluid model with a Lagrangian MPS structure model. Khayyer et al. (2017c) investigated key issues for development of a reliable FSI solver for simulation of hydroelastic slamming in the context of MPS method. Khayyer et al. (2018a) presented a comparative study on MPS-based and ISPH-based FSI solvers with Newtonian and Hamiltonian structure models. Khayyer et al. (2018b) developed a novel Enhanced ISPH-SPH FSI solver for simulation of incompressible fluid flow-elastic structure interaction. Khayyer et al. (2018c) presented a multi-resolution MPSbased FSI solver for accurate and efficient simulations of interactions between incompressible fluid flows with elastic structures. Falahaty et al. (2018a) incorporated stress point integration in projection-based FSI modelling in the framework of DPD (Dual Particle Dynamics).
