Landslide generated impulse waves.

Abstract

Landslide generated impulse waves were investigated in a two-dimensional physical laboratory model based on the generalized Froude similarity. Digital particle image velocimetry (PIV) was applied to the landslide impact and wave generation. Areas of interest up to 0.8 m by 0.8 m were investigated. The challenges posed to the measurement system in an extremely unsteady threephase flow consisting of granular matter, air, and water were considered. The complex flow phenomena in the first stage of impulse wave initiation are: high-speed granular slide impact, slide deformation and penetration into the fluid, flow separation, hydrodynamic impact crater formation, and wave generation. During this first stage the three phases are separated along sharp interfaces changing significantly within time and space. Digital masking techniques are applied to distinguish between phases thereafter allowing phase separated image processing. PIV provided instantaneous velocity vector fields in a large area of interest and gave insight into the kinematics of the wave generation process. Differential estimates such as vorticity, divergence, elongational, and shear strain were extracted from the velocity vector fields. The fundamental assumption of irrotational flow in the Laplace equation was confirmed experimentally for these non-linear waves. Applicability of PIV at large scale as well as to flows with large velocity gradients is highlighted.

Dynamics of crater formations in immersed granular materials

“…In immersed granular material, one reports craters generated by an underwater vortex ring [18], involving fluidized ejecta dynamics, or underwater impact craters generated by landslide [19]. Craters in immersed granular materials can result either from two-phase or threephase flows.…”

Numerical simulation of tsunami generation by cold volcanic mass flows at Augustine Volcano, Alaska

“…Mass flow thickness is estimated from conservation of mass and the three deformation coefficients have values in the range 1≤k a <2, 1≤k n <1.4, and 0≤k l <0.8. These values are based on experimental results (Watts, 1997;Fritz, 2002), numerical analysis Locat, et al, 2004), and case studies of mass flow tsunami generation (Greene et al, 2006;Walder et al, 2006). We use the model described by Eqs.…”

“…Recent studies of impact-generated waves have described the region from the shoreline to the area where the mass flow stops on the sea floor as the splash zone (Walder et al, 2003;Walder et al, 2006). The splash zone is an area of complicated wave dynamics and chaotic water behavior (Fritz et al, 2003a;Fritz et al, 2003b;Fritz et al, 2004) and for Augustine Volcano, this zone extends from about 4 to 9 km beyond the shoreline. Beyond the splash zone is a near-field zone, and this zone is the area of the wave domain where a well defined wave evolves from the splash zone.…”

Analysis of the Tangjiaxi landslide-generated waves in the Zhexi Reservoir, China, by a granular flow coupling model

“…A large number of studies have been done on landslide-induced impulse waves, including analytical, physical, and numerical methods. The analytical solutions are derived from extensive sources, such as experimental and empirical formulae, where their application scope is limited to their sources (Kamphuis et al, 1970;Wieland et al, 1999;Ursell et al, 1960;Fritz et al, 2002;Huber and Hager, 1997;Heller, 2007;Yin and Wang, 2008). Due to the considered simplifications for analytical solutions, it is hard to have an overall grasp of the landslide-induced impulse wave disaster (Heller et al, 2009).…”