Tags:
Mechanics,
Fluid mechanics
Publications

Kim, Jihwan; Pedersen, Geir Kleivstul; Løvholt, Finn & LeVeque, Randall J. (2017). A Boussinesq type extension of the GeoClaw model  a study of wave breaking phenomena applying dispersive long wave models. Coastal Engineering.
ISSN 03783839.
122, s 75 86 . doi:
10.1016/j.coastaleng.2017.01.005
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The nonlinear shallow water model is widely used in the study of tsunami propagation, but an increasing number of studies are dedicated to the dispersion dynamics of tsunamis. If the wave dispersion becomes important, Boussinesqtype models are often used. In this work, a general purpose Boussinesq solver, BoussClaw, is introduced for modeling nonlinear dispersive tsunami propagation, taking into account inundation. The BoussClaw model is an extension of the GeoClaw tsunami model. It employs a hybrid of finite volume and finite difference methods to solve Boussinesq equations from the literature, which are based on the depthaveraged velocity and include enhanced dispersion properties. On the other hand, in the selected formulation only some nonlinearity is retained in the dispersion term. In order to validate BoussClaw, numerical results are compared to analytic solutions, solutions obtained by preexisting models, and laboratory experiments. Even though the equations of BoussClaw are not fully nonlinear they perform far better than standard Boussinesq equations with only linear dispersion terms. Furthermore, the wave steepening and breaking are carefully scrutinized, and we demonstrate that the point of wave breaking may be wrongly identified in many of the commonly used Boussinesq models.

Lacasse, Suzanne; Liu, Zhongqiang; Kim, Jihwan; Choi, Jung Chan & Nadim, Farrokh (2017). Reliability of Slopes in Sensitive Clays, In Vikas Kumar Singh Thakur; JeanSébastien L'Heureux & Ariane Locat (ed.),
Landslides in Sensitive Clays  From Research to Implementation.
Springer.
ISBN 9783319564869.
Chapter 45.
s 511
 537
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Risk and probabilistic analyses have now had enough applications that make them effective to use in practice. The approach provides more insight than deterministic analyses alone. They help reduce uncertainty and focus on safety and costeffectiveness. The paper illustrates the use of reliability methods for the analysis of slopes in sensitive clays with examples of the calculation of probability of failure and runout for the Finneidfjord and Rissa landslides in Norway. The input, model and results of the probabilistic slope analysis are described, including the uncertainties in the parameters, triggers and calculation model, as well as a brief review of the principles of the reliability approach. Reliability approaches do not remove uncertainty nor do they alleviate the need for judgment. They provide a way to quantify the uncertainties and to handle them consistently. Site investigations, laboratory test programs, limit equilibrium and deformation analyses, instrumentation, monitoring and engineering judgment are necessary inputs to the reliability approach. Landslide events, often unwittingly, are triggered or aggravated by human activity, such as change in topography (e.g. excavation or surcharge) and change in drainage conditions. Climate change can increase the frequency of landslide. The paper proposes that a probabilistic model in an event tree format should be included to ensure that all failure modes and the uncertainties have been covered and that slope failure mitigation measures are quickly available.

Løvholt, Finn; Bondevik, Stein; Laberg, Jan Sverre; Kim, Jihwan & Boylan, Noel (2017). Some giant submarine landslides do not produce large tsunamis. Geophysical Research Letters.
ISSN 00948276.
44(16), s 8463 8472 . doi:
10.1002/2017GL074062
Full text in Research Archive.
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Landslides are the secondmost important cause of tsunamis after earthquakes, and their potential for generating large tsunamis depend on the slide process. Among the world's largest submarine landslides is the Storegga Slide that generated an oceanwide catastrophic tsunami, while no traces of a tsunami generated from the similar and nearby Trænadjupet Slide have been found. Previous models for such landslide tsunamis have not been able to capture the complexity of the landslide processes, and are at odds with geotechnical and geomorphological data that reveal retrogressive landslide development. The tsunami generation from these massive events are here modeled with new methods that incorporate complex retrogressive slide motion. We show that the tsunamigenic strength is closely related to the retrogressive development, and explain for the first time, why similar giant landslides can produce very different tsunamis, sometimes smaller than anticipated. Because these slide mechanisms are common for submarine landslides, modeling procedures for dealing with their associated tsunamis should be revised.

Løvholt, Finn; Pedersen, Geir Kleivstul; Harbitz, Carl Bonnevie; Glimsdal, Sylfest & Kim, Jihwan (2015). On the characteristics of landslide tsunamis. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.
ISSN 1364503X.
373(2053) . doi:
10.1098/rsta.2014.0376
Full text in Research Archive.
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This review presents modelling techniques and processes that govern landslide tsunami generation, with emphasis on tsunamis induced by fully submerged landslides. The analysis focuses on a set of representative examples in simplified geometries demonstrating the main kinematic landslide parameters influencing initial tsunami amplitudes and wavelengths. Scaling relations from laboratory experiments for subaerial landslide tsunamis are also briefly reviewed. It is found that the landslide acceleration determines the initial tsunami elevation for translational landslides, while the landslide velocity is more important for impulsive events such as rapid slumps and subaerial landslides. Retrogressive effects stretch the tsunami, and in certain cases produce enlarged amplitudes due to positive interference. In an example involving a deformable landslide, it is found that the landslide deformation has only a weak influence on tsunamigenesis. However, more research is needed to determine how landslide flow processes that involve strong deformation and long runout determine tsunami generation.
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Gylfadottir, Sigridur Sif; Kim, Jihwan; Helgason, Jon Kristinn; Brynjólfsson, Sveinn; Höskuldsson, Ármann; Jóhannesson, Tómas; Harbitz, Carl Bonnevie & Løvholt, Finn (2016). The 2014 Lake Askja rockslide tsunami – optimization of landslide parameters comparing numerical simulations with observed runup.

Kim, Jihwan & Løvholt, Finn (2016). Sensitivity study of the Storegga Slide tsunami using retrogressive and viscoplastic rheology models.

Kim, Jihwan; Løvholt, Finn & Issler, Dieter (2016). Finite volume methods for submarine debris flows and generated waves.

Kim, Jihwan & Issler, Dieter (2015). Finite volume methods for submarine debris flow with HerschelBulkley rheology. Geophysical Research Abstracts.
ISSN 10297006.
17

Løvholt, Finn; Kim, Jihwan & Harbitz, Carl Bonnevie (2015). NH14A03: Modeling tsunamis induced by retrogressive submarine landslides.

Løvholt, Finn; Kim, Jihwan; Harbitz, Carl Bonnevie & Pedersen, Geir Kleivstul (2015). Tsunami generation due to submerged blocks and deformable landslides involving retrogression. Full text in Research Archive.
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Published Nov. 18, 2014 2:41 PM
 Last modified Oct. 5, 2016 11:33 AM