### ASI-ISPH Partitioned Coupling Analysis for Fluid-Structure Interaction

Abstract

In order to evaluate robustness of a building against tsunamis, it is necessary
to consider the interaction between building and tsunami. The Fluid-Structure
Interaction (FSI) analysis is appropriate for this purpose. Most existing
FSI methods are based on the finite element method (FEM) and formulated
with presupposition that the structure models are discretized with the
solid elements. Therefore, there are few applications for large-scale cases
such as tsunamibuilding interaction problems because of the huge computational
cost. In this research, we propose a partitioned FSI method based on the
FEM using the beam element that is effective for analyses of framed structures
such as buildings. The ASI-Gauss technique, which can efficiently compute
yielding and fracture, is applied for the FEM. The particle method is used
as a fluid analysis scheme. Especially, the ISPH, which can obtain accurate
pressure values and can conserve volumes well, is applied for the particle
method. Besides, the Explicit Represented Polygon wall boundary model (ERP
model) is introduced into ISPH to evaluate fluid forces exerting on the
boundary. We extend the ERP model to the implicit particle method and the
SPH because the original model was formulated for the Explicit MPS. In
addition, the representation of the Dirichlet condition for velocity by
the ERP model is generalized to be applied to the moving boundary problems.
The boundary shape of the beam member is interpolated by using the coordinates
of the nodes on both ends of the element, the predefined sectional shape
of the beam and the deformation computed by the structural analysis. As
described above, the fluid forces exerting on the beam elements are obtained
from the fluid analysis. These forces are converted into external forces
for the structural analysis. A hydrostatic pressure problem and a dam break
problem with an elastic obstacle were solved to verify. The numerical result
showed that the proposed method can solve the fluid-structure interaction
problem with sufficient precision.

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