2024 Volume 80 Issue 7 Article ID: 23-00064
Movement mechanism of tsunami boulders was analyzed by three-dimensional numerical simulations of coupled fluid-solid motions. Flume experiments were firstly performed where dam-break flows moved tsunami boulders. Then, the numerical simulations were performed on the experimental results. The numerical simulation results reproduced well the relation between dam depths and movement distances of tsunami boulders measured in the plural experiments and time variation of water levels around a tsunami boulder. A control volume around the tsunami boulder that is fixed to the moving boulder was determined, and the temporal variation of the fluid force and momentum exchange at the border of the control volume were revealed from the numerical simulation results. Moreover, investigation on fluid and contact forces revealed the characteristic mechanism where tsunami boulders move so that streamwise fluid forces balance to the friction forces exerted from the channel bottom that is roughly governed by the buoyancy of the tsunami boulder.
