Numerical Modelling of Hydrodynamic Impact of Tsunami on Coastal Structures in the Presence of Curved Sea Wall

Abstract

Tsunami, after arrival at the shore, flows and inundates hundreds of metre inland. The only way of shelter is to take cover on a high elevated structure as it is not possible to evacuate horizontally due to unpredicted nature and high approach velocity of tsunami bore. This high-velocity bore can impact the nearshore structures with extreme loads resulting in catastrophic losses. Therefore, it is necessary to adopt coastal protection measures such as sea walls which can reduce the effect of high impact and hydrodynamic loads on structures. In this study, three-dimensional Reynolds-averaged Navier–Stokes (RANS) equations were solved using finite volume method (FVM) for incompressible two-phase flow (air–water) utilizing numerical solver “interFoam”. Dam-break condition was used to generate the extreme bore to study its interaction with the square structure that represents the coastal elevated structure. The variation of the tsunami force on the structure was investigated by considering two types of curved sea walls as protection measures. The curved face sea wall having nine different radii increasing from bottom to top and another with parabolic profile at the bottom and circular at the top are placed at a distance 1D (D being the width of structure) from structure face. The results showed that the force on the structure reduced substantially and also differs with the change in geometric shape of the front face of the sea wall and thus helped in achieving an overall understanding of physical mechanisms that occurs due to extreme bore impact on the onshore structures. These results will help in guiding the practicing engineering for proper design of the tsunami shelter buildings as well as the design of sea walls in the tsunami risk zones.