ABSTRACT

A tsunami wave effect on the oil tank storage was numerically investigated with the Fluid-Structure Interaction (FSI) analysis. The calculation was conducted for the tsunami water tank experiment in which the scale ratio of modeled tank to real tank storage was 1/100. In order to assess the dependency of tank stiffness on fluid and tank motion, the Young's modulus was parametrically changed and the stress on tank side was calculated. When the tsunami arrived at the tank and the hydrodynamic force took a maximum value, it was found that the fixed tank with high stiffness had large risk for side wall buckling that led to oil spill.

INTRODUCTION

When the Great East Japan Earthquake occurred in 2011, a massive tsunami arrived at Miyagi prefecture, and 22 oil storage tanks at Kesennuma bay area were broken and collapsed by the tsunami and a large amount of oil were flowed into the sea. The spilled oil was fired due to the sparks from washed automobiles and broken electric wires, and the second fire disaster caused serious damage (Zama, 2012). This tsunami fire disaster due to the oil spill from tank storage was firstly observed at the 2011 Earthquake although Japan has experienced many earthquakes. However, the ocean countries that have many industrial parks at bay area take a risk of tsunami fire disaster and we have to develop the risk management system for such accidents. Especially, in Japan, the Nankai Trough Earthquake assumes to be occurred in a few decades, we also have to find a new innovative technology to prevent the accidents related to tsunami.

Although tsunami simulation has been carried out by many researchers with the standard grid-based Computational Fluid Dynamics (CFD) or particle method, the advanced CFD coupling oil spill with multiphase flow calculation was not frequently conducted. Kyaw (2017a) carried out the hybrid simulation coupling a generic tsunami calculation in a wide area with oil parcel tracking. In their study, the initial condition of the oil parcel tracing was given based on the estimation by the Osaka Prefecture Petrochemical Disaster Prevention Cabinet Headquarters (2014) and the setting of the initial amount of spilled oil were arbitrary. As discussed in Kyaw (2017b), the motion of oil tank storage in tsunami flow can be classified into some types such as sliding, floating, collapse, slide buckling, and bottom drop. Kyaw (2017b) investigated the dynamic motion of tank storage under tsunami overflow with multiphase CFD but they did not considered the structure change of tank body by hydrodynamic force. The Fluid-Structure Interaction (FSI) analysis is a useful simulation method for evaluating the relationship between hydrodynamic force of tsunami and structure change of tank but it requires large numerical cost compared with a pure CFD for solving only fluid motion, and the study on dynamic tank motion with FSI analysis is not so much reported. Sugatsuki (2013) carried out the simplified FSI analysis to investigate the tank damage by tsunami but the method of the FSI was one-way coupling and the effect of structure deformation was not considered in the calculation of fluid region. In order to investigate the relation between hydrodynamic property of tsunami and structural property of tank precisely, we have developed the simulation method based FSI analysis for the multiphase flow around single tank storage and estimated the risk of tank buckling due to tsunami.

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