Author(s): Takaaki Abe; Yasuhiro Yoshikawa; Yoshishige Satoh; Akashi Itoh; Satomi Yamaguchi
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Abstract: In cold snowy regions tsunami in rivers can cause river ice breakup, ice debris transport and consequent collisions between ice floes and river structures. The main aim of this study is to develop a practical model for simulating interactions of tsunami, river ice floes and river facilities such as sluice gates. The numerical method we use is based on the Moving Particle Semi-implicit (MPS) method, which is capable of simulating a wide variety of hydraulic problems such as solid-liquid two-phase flows and the blocking of a bridge by driftwood. The method is applied to some numerical experiments and verifications are made in terms of flow field and floe movements. First we conducted a simple numerical test, that is, the time variation of translational velocity of a floating rigid body with density equal to that of water in a water tank. The MPS method resulted in a smooth time history of velocity and the position was fixed through the simulation time. Second, applicability of the MPS method to ice sheet perturbation, ice floe movements in a uniform flow and resulting blocking of a narrow section by ice-jamming, is demonstrated through the comparison with the ice-jamming hydraulic experiment. By comparing series of calculation snapshots with corresponding laboratory photographs, simulation-experiment qualitative agreement was obtained. Finally, the method is applied to the real-scale simulation of tsunami wave intrusion into a frozen sluice way to investigate the wave characteristics accompanied by substantial ice floe movements. As a result, in cases with relatively small tsunami wave height, the generated wave was damped a little bit due to ice cover, however, in cases with larger wave height pile-up of ice floes occurred, the risks of which several ice researchers claimed so far. This work highlights the potential risks of ice floes and succeeds in development of a method for simulating river tsunami with ice.
Year: 2014