Numerical modeling of debris transport due to tsunami flow in a coastal urban area

Many numerical models have been developed to estimate the behavior of debris generated by tsunamis. How-ever, such numerical models have been validated through comparison with experimental data under simple conditions such as simple topography. Therefore, model applicability to actual topographic conditions such as ports and urban areas remains largely unknown. In this study, the modeling of contact with the seafloor and collision with buildings in an existing debris transport model (STOC-DM) is improved to enhance actual practical applicability. Moreover, debris numerical simulations are conducted using the results of hydrodynamic nu-merical simulations with different water level data obtained under the same wave generation conditions as used in the experiments, and the numerical results are compared with results obtained from debris experiments conducted in a previous study using a coastal urban model. The model improvements contribute to reproducing the statistical characteristics of debris position and the final arrival position; however, the modeled results on debris velocity cannot reproduce the experimental results. Therefore, sensitivity analysis is also conducted by applying disturbances not only to the fluid but also to the parameters of the debris model, e.g., drag coefficient, inertia coefficient, and friction coefficient. The combination results considering both disturbances improve the distribution of the debris velocity that cannot be reproduced using fluid disturbance alone.

Automated summary

This study improves the practical applicability of an existing debris transport model by enhancing the modeling of contact with the seafloor and collision with buildings. The numerical simulations and comparison with experimental results show that the model can reproduce the statistical characteristics of debris position and final arrival position, but has limitations in reproducing debris velocity. Sensitivity analysis and considering disturbances in both fluid and debris model parameters improve the distribution of debris velocity.