Experimental and numerical investigation on tsunami run-up flow around coastal buildings

Abstract

Inland tsunami flows can be greatly affected by the presence of coastal buildings. The present study experimentally and numerically investigated the effects of nine different building layouts on 1) the tsunami inundation process and spatial velocity distribution, 2) the flow depth and velocity at a specific point, and 3) the extent of the area where shielding effects take place. High-speed video footage, PIV analysis, and the time history of flow depth, velocity, and momentum flux demonstrated significant differences in the tsunami run-up behaviour among the different building layouts considered. However, it was also shown that a decrease in the flow velocity always appears in front of and immediately behind the building(s), regardless of their layouts.The OpenFOAM simulations performed revealed that significant shielding effects appear in the leeside of the building. These findings can be used when considering where to place evacuation buildings, as constructing them directly behind another study structure could reduce construction costs and increase their stability. The obtained results were also applied to partially validate the method for calculating the channeling effects of tsunami loads provided in ASCE 7-16.

Tsunami-like Flow-Induced Forces on the Landward Structure behind a Vertical Seawall with and without Recurve Using OpenFOAM

“…Regularly applied methods that have been used in the tsunami interaction studies are the Finite Volume method [45][46][47], the Arbitrary Lagrangian-Eulerian method [48], the Finite Element method [49], the coupled FEM and meshless method [50,51], the coupled FEM and FVM methods [52] and particle-based methods, such as the Smoothed Particle Hydrodynamics [53], the Moving Semi-Implicit method and the Meshless Local Petrov Galerkin method [50,54]. With increasing computational resources in recent decades, numerical simulations can provide a more in-depth understanding of flow interaction processes [55,56]. From the range of available methods, the open-source FVM solver OpenFOAM is applied in the present study to investigate the interaction processes between tsunamis and inland structures in the presence of seawalls.…”

Numerical Investigation of Countermeasure Effects on Overland Flow Hydrodynamic and Force Mitigation in Coastal Communities

“…OlaFlow uses the finite volume method (FVM) for spatial discretization and solves Reynolds averaged Navier-Stokes (RANS) equations for incompressible flows by using a PIMPLE algorithm (a mixture of the pressure implicit with splitting of operators (PISO) and semi-implicit method for pressure linked equations (SIMPLE)) (Park et al, 2017). The volume of fluid (VOF) approach was used to track the free surface displacement from water-air phases (Ishii et al, 2021). To model the turbulence, the k solver was selected for the current simulation because this turbulence closure solver is more effective than other turbulent closure solvers (e.g., k-ϵ model) in modeling partially separated flows when the overland flow propagates and then is separated by building rows in the constructed environment (Qin et al, 2018).…”

“…The study pointed out the importance of considering the built environment in predicting forces on inland buildings rather than the traditional method by considering drag coefficients (with a recommended value of 2.0). Ishii et al (2021) performed experimental and numerical investigations on the effects of different building arrangements on tsunami-induced overland flow hydrodynamics and the performance of shielding effects of macro-roughness on the lee side of the buildings. Moreover, Moris et al (2021) examined the influence of the number of building rows providing shelter on inundation depth, velocity, and loading mitigation in coastal communities.…”

Mitigating tsunami effects on buildings via novel use of discrete onshore protection systems

“…Moreover, Fukui et al (2022) performed a direct simulation of inundated developed urban areas compared to that of bare earth with roughness and stated that buildings significantly influenced the overland flood propagation. The significant effect of buildings on tsunami flow has been studied experimentally and numerically using OpenFOAM by Ishii et al (2021). They also revealed a considerable shielding effect occurred in the leeside of the building where this condition can be used for constructing safer evacuation strategies.…”