NUMERICAL SIMULATION OF BOTTOM TOPOGRAPHY CHANGE DUE TO TSUNAMI IN COASTAL SEA AREA WITH ABRUPT EXPANSION REGION

Abstract

 Hydraulic experiments and numerical simulations were carried out in order to analyze the influence of the planar shape of coastal sea area on sediment transport and bottom topography change due to tsunami. High velocity flow occurred due to the passage of tsunami through the abrupt expansion and a circulation flows took place in the rear area of the structure. The circulation flows generated behind the structure were found to be the same scale regardless of the length of the rear area. Therefore, deposit area with the same position and scale was formed even if the scale of the rear area was different. The numerical results also revealed that the introduction of the diffussion terms into the equations of fluid motion and suspended sediment are necessary to reproduce flow structure and topography change.