Tsunami Damping due to Bottom Friction Considering Flow Regime Transition and Depth-Limitation in a Boundary Layer

Hitoshi Tanaka, Nguyen Xuan Tinh, Ahmad Sana

Research output: Contribution to journalArticlepeer-review


According to recent investigations on bottom boundary layer development under tsunami,
a wave boundary can be observed even at the water depth of 10 m, rather than a steady flow type
boundary layer. Moreover, it has been surprisingly reported that the tsunami boundary layer remains
laminar in the deep-sea area. For this reason, the bottom boundary layer under tsunami experiences
two transitional processes during the wave shoaling: (1) flow regime transition in a wave-motion
boundary layer from laminar to the turbulent regime, and (2) transition from non-depth-limited
(wave boundary layer) to depth-limited boundary layer (steady flow boundary layer). In the present
study, the influence of these two transition processes on tsunami wave height damping has been
investigated using a wave energy flux model. Moreover, a difference of calculation results by using
the conventional steady flow friction coefficient was clarified.
Original languageEnglish
JournalJournal of Marine Science and Engineering
Publication statusPublished - Oct 5 2022

Cite this