Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Towards development of entirely meshfree Lagrangian FSI solvers
for slamming of composite marine panels
Abbas Khayyer, Hitoshi Gotoh, Yuma Shimizu
Department of Civil and Earth Resources Engineering, Kyoto University
Kyoto, Japan

The pioneering work in the context of particle methods targeting theFSI corresponding to the composite materials is the one by Khayyer etal. (2021a). In their work, a Hamiltonian SPH (HSPH) structure model(Khayyer et al., 2018a) is applied towards simulation of compositestructure. Their HSPH structure model as well as its corresponding
entirely Lagrangian FSI solver were shown to possess notableaccuracy, robustness and conservation properties in reproduction ofelastic deformation of composite materials thanks to the model
configuration of structure model within variationally consistent
Hamiltonian framework and Total Lagrangian formulation.

ABSTRACTThe paper aims at denoting ongoing efforts for development of accurate
and stable entirely Lagrangian meshfree FSI solvers towards
reproduction of hydroelastic slamming on composite marine panels.
For this purpose, two SPH-based structure models, namely Updated
Lagrangian SPH (ULSPH) and Hamiltonian SPH (HSPH), areinvestigated for the simulation of composite materials withcomprehensive discussions about the approaches to enhance theirperformance, i.e. inclusion of stress point integration concept resultingin ULSPH-SP structure model. After the validations of structure
models, the structure models are coupled with a refined IncompressibleSPH (ISPH) fluid model for the configuration of entirely Lagrangian
meshfree FSI solvers. Validation of the FSI solvers is carried out
through an FSI benchmark test for which theoretical solution exists.
The FSI solvers are finally applied to the slamming simulation
corresponding to a composite marine panel, where the accuracy andstability of the solvers are examined.

Against the HSPH model incorporating Total Lagrangian configuration,
another leading branch of SPH structure model corresponds to theUpdated Lagrangian SPH (ULSPH) structure model (e.g. Gray et al.,2001). The ULSPH-based formulation is known advantageous toreproduce large deformation of structure (e.g. Nguyen et al., 2017),
whilst it likely suffers from an inferior robustness induced by rank
deficiency and tensile instability.
A lot of effort have been devoted for elimination of rank deficiency andtensile instability in ULSPH structure models. A relevant approachcorresponds to the incorporation of stress points (Dyka and Ingel, 1995;
Dyka et al., 1997; Randles and Libersky, 2000). In this approach, anadditional set of computational points providing mechanicalinformation (stress, σ) is introduced in calculation of structure
dynamics. Falahaty et al. (2018) presented a particle-based FSI solver
by enhancing an updated Lagrangian meshfree structure model withstress point concept. They provided detailed discussions on the stressboundary conditions with stress points, which can guarantee rigorous
satisfaction of stress boundary conditions with respect to the usual
nodal integration approaches. This advantageous feature of stress pointis expected to be effective for precise treatments at material boundaries
of composite structures, although particle-based structure model
benefitting from stress point has not been applied to simulation ofcomposite materials.

KEY WORDS:

composite structure; Fluid-Structure Interaction;
Smoothed Particle Hydrodynamics; particle method

INTRODUCTION
The precise estimation of interactions between fluids and deformablestructures have been of key importance in coastal/ocean engineering
applications. In specific, in line with the advancement of technology incomposite materials leading to lightweight elastic structures, thereliable computational modelling of hydroelastic slamming between
fluid and composite deformable structures have become considerably
significant. As for the numerical modelling, Lagrangian mesh-freecomputational methods (particle methods; Gotoh and Khayyer, 2018;Gotoh, 2018), represented by Smoothed Particle Hydrodynamics (SPH;Gingold and Monaghan, 1977) or Moving Particle Semi-implicit (MPS;
Koshizuka and Oka, 1996), would bring advantageous contributions in
fluid and structure dynamics with complex moving boundary
conditions and mutual Fluid-Structure Interaction (FSI), as presented ina lot of recent studies (e.g. Liu and Zhang, 2019; Luo et al., 2021;
Gotoh et al., 2021; Lyu et al., 2022). On the other hand, numericalmodelling of FSI with composite structures has been very rarely
studied within the framework of particle method.

In regard to these backgrounds, this work aims at introducing ourongoing efforts towards development of reliable entirely Lagrangian
meshfree FSI solvers for simulation of hydroelastic slamming oncomposite marine panels. First, three particle-based structure models,
namely Updated Lagrangian SPH (ULSPH), Hamiltonian SPH(HSPH), and ULSPH incorporating Stress Points (ULSPH-SP) are1952