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A Simulation of Landslide-Generated Waves Using a Fully Implicit ISPH

Nishida, Kosei LU (2020) In TVVR 20/5002 VVRM01 20191
Division of Water Resources Engineering
Abstract
Smoothed Particle Hydrodynamics (SPH) is used to study the mechanisms of landslide-generated waves. As the landslide dynamics and the evaluation of impact forces acting on water are most important, landslide is modelled as a highly viscous fluid. Incompressible SPH (ISPH) is used for fluid simulation. Since the landslide is assumed as highly viscous fluid, it needs to satisfy the condition for the viscous term with respect to time step in addition to CFL condition. To use moderate time step, we adopt an ISPH with a fully implicit time integration. The rheology of the soil is characterized by Bingham fluid model. The yield stress is determined by Mohr-Coulomb failure criterion. At the interface of multiphase flows, a conventional SPH... (More)
Smoothed Particle Hydrodynamics (SPH) is used to study the mechanisms of landslide-generated waves. As the landslide dynamics and the evaluation of impact forces acting on water are most important, landslide is modelled as a highly viscous fluid. Incompressible SPH (ISPH) is used for fluid simulation. Since the landslide is assumed as highly viscous fluid, it needs to satisfy the condition for the viscous term with respect to time step in addition to CFL condition. To use moderate time step, we adopt an ISPH with a fully implicit time integration. The rheology of the soil is characterized by Bingham fluid model. The yield stress is determined by Mohr-Coulomb failure criterion. At the interface of multiphase flows, a conventional SPH framework applies the material properties from neighboring particles for the target particle even though some of them are belonging to a different material. Therefore, we modify the approach to adopt the material properties of the same phase on the target particle. Three validations are made to study the accuracy of the proposed method. It is concluded that the present method is capable of describing the wave generation and propagation phenomena and capturing the soil behavior based on the Mohr-Coulomb parameters. (Less)
Popular Abstract
On December 22, 2018, the coastal area of Sunda Strait in Indonesia experienced tsunami waves generated by the lateral collapse of Anak Krakatau volcano due to its volcanic activity. In Japan, 1792 Unzen earthquake and tsunami is also one of those types of disaster. In Shimabara (Nagasaki Prefecture), Mt. Mayuyama in front of Mt. Unzen had a huge landslide due to the volcanic activities. The sediments were sliding into the sea, causing the tsunami that struck the coastal line at the other side of the ocean in Higo (Kumamoto Prefecture). Compared to earthquakes, landslide may create waves with relatively shorter wave lengths and locally higher wave amplitudes, inducing large runups among the adjacent area. Hence, a better understanding of... (More)
On December 22, 2018, the coastal area of Sunda Strait in Indonesia experienced tsunami waves generated by the lateral collapse of Anak Krakatau volcano due to its volcanic activity. In Japan, 1792 Unzen earthquake and tsunami is also one of those types of disaster. In Shimabara (Nagasaki Prefecture), Mt. Mayuyama in front of Mt. Unzen had a huge landslide due to the volcanic activities. The sediments were sliding into the sea, causing the tsunami that struck the coastal line at the other side of the ocean in Higo (Kumamoto Prefecture). Compared to earthquakes, landslide may create waves with relatively shorter wave lengths and locally higher wave amplitudes, inducing large runups among the adjacent area. Hence, a better understanding of LGWs is of great importance in hazard assessments. Because of the uncertainty regarding landslide characteristics and the absence of the observed data, a proper and reasonable numerical model is required. Our research group has already developed numerical simulation tools to tackle tsunami related problems such as stabilized ISPH method for tsunami propagation and inundation, a SPH with an impulse method for fluid-structure interaction and a SPH-DEM coupling method for fluid-soil interaction. In this paper, we improve the current method to study landslide-generated waves events and capture the features of the wave generation and propagation processes. Three validations are made to study the accuracy of the proposed method. It is concluded that the present method is capable of describing the wave generation and propagation phenomena and capturing the soil behavior. (Less)
Please use this url to cite or link to this publication:
author
Nishida, Kosei LU
supervisor
organization
course
VVRM01 20191
year
type
H2 - Master's Degree (Two Years)
subject
keywords
SPH, Landslide-generated waves, non-newtonian fluid, multiphase flow
publication/series
TVVR 20/5002
report number
20/5002
ISSN
1101-9824
language
English
additional info
Examiner: Hans Hanson
id
9006553
date added to LUP
2020-03-16 09:20:26
date last changed
2020-03-16 09:20:26
@misc{9006553,
  abstract     = {{Smoothed Particle Hydrodynamics (SPH) is used to study the mechanisms of landslide-generated waves. As the landslide dynamics and the evaluation of impact forces acting on water are most important, landslide is modelled as a highly viscous fluid. Incompressible SPH (ISPH) is used for fluid simulation. Since the landslide is assumed as highly viscous fluid, it needs to satisfy the condition for the viscous term with respect to time step in addition to CFL condition. To use moderate time step, we adopt an ISPH with a fully implicit time integration. The rheology of the soil is characterized by Bingham fluid model. The yield stress is determined by Mohr-Coulomb failure criterion. At the interface of multiphase flows, a conventional SPH framework applies the material properties from neighboring particles for the target particle even though some of them are belonging to a different material. Therefore, we modify the approach to adopt the material properties of the same phase on the target particle. Three validations are made to study the accuracy of the proposed method. It is concluded that the present method is capable of describing the wave generation and propagation phenomena and capturing the soil behavior based on the Mohr-Coulomb parameters.}},
  author       = {{Nishida, Kosei}},
  issn         = {{1101-9824}},
  language     = {{eng}},
  note         = {{Student Paper}},
  series       = {{TVVR 20/5002}},
  title        = {{A Simulation of Landslide-Generated Waves Using a Fully Implicit ISPH}},
  year         = {{2020}},
}