  A 3D fluid-structure interaction solver based on an improved
weakly-compressible moving particle simulation (WC-MPS) method and a
geometrically nonlinear shell structural model is developed and applied to
hydro-elastic free-surface flows. The fluid-structure coupling is performed by
a polygon wall boundary model that can handle particles and finite elements of
distinct sizes. In WC-MPS, a tuning-free diffusive term is introduced to the
continuity equation to mitigate non-physical pressure oscillations. Discrete
divergence operators are derived and applied to the polygon wall boundary, of
which the numerical stability is enhanced by a repulsive Lennard-Jones force.
Additionally, an efficient technique to deal with the interaction between fluid
particles placed at opposite sides of zero-thickness walls is proposed. The
geometrically nonlinear shell is modeled by an unstructured mesh of six-node
triangular elements. Finite rotations are considered with Rodrigues parameters
and a hyperelastic constitutive model is adopted. Benchmark examples involving
free-surface flows and thin-walled structures demonstrate that the proposed
model is robust, numerically stable and offers more efficient computation by
allowing mesh size larger than that of fluid particles.
