Article
Acoustics
Xiao Siyou, Yang Junwei, Wei Zhongju
Summary: This study introduces the progresses in the estimation of the impact load of granular flow against a rigid wall. It reveals that the volume of granular flow is a key factor in determining the evolution of the impact load and proposes a simplified model to consider the relationship between multiple physical parameters.
SHOCK AND VIBRATION
(2022)
Article
Engineering, Chemical
Wangxin Yu, Xiaoliang Wang, Qingquan Liu, Xuedong Chen, Huaning Wang
Summary: This study investigates the dynamic interaction between fast granular flow and an existing deposit using the Savage-Hutter model. Three distinct flow patterns are identified, and a new normal shock relationship for granular flow is proposed.
Article
Geosciences, Multidisciplinary
Ryan K. Cassotto, Justin C. Burton, Jason M. Amundson, Mark A. Fahnestock, Martin Truffer
Summary: The study found that before the calving of an outlet glacier in Greenland, the flow coherence of the proglacial ice melange would be lost, with individual icebergs undergoing random displacements. These fluctuations are likely caused by buckling and rearrangements of the quasi-two-dimensional material, implicating ice melange as a mechanical inhibitor of iceberg calving.
Article
Engineering, Geological
C. W. W. Ng, Z. Li, Y. D. Wang, H. Liu, S. Poudyal, W. A. R. K. De Silva
Summary: A deflector is a structure that prevents debris flow from damaging downstream infrastructures and human lives. The interaction mechanism between debris flow and deflector has not been scientifically elucidated. Flume tests and numerical simulations were used to study the influence of deflector geometry on flow-deflector interaction and barrier height reduction. The optimal deflector configuration has a projected length of LP/h0 = 1.0 and angles of 0 degrees and 45 degrees. Installing a deflector reduces the barrier height by up to 50% while preventing overspilling when HB/h0 < 4.7.
ENGINEERING GEOLOGY
(2023)
Article
Engineering, Environmental
Bei Zhang, Yu Huang
Summary: Protective barriers play a crucial role in resisting the impact of granular flows. However, there is a need for further investigation on how to estimate the impact force accurately. Traditional practices assume that the lower part of the flow has the same velocity as the bulk flow, but our observations show that the lower part consistently has lower velocities due to enhanced granular shear behavior within the boundary layer. Using the bulk velocity for impact force estimation may result in underestimation of approximately 10-30%. Based on our numerical results, we suggest adopting the average velocity of the upper 50% of the flow body for impact force estimation.
BULLETIN OF ENGINEERING GEOLOGY AND THE ENVIRONMENT
(2022)
Article
Geosciences, Multidisciplinary
Alexander M. Taylor-Noonan, Elisabeth T. Bowman, Brian W. McArdell, Roland Kaitna, Jim N. McElwaine, W. Andy Take
Summary: The presence of a pore fluid significantly increases the mobility of granular flows. Wet granular flows show flow dilation and strong variation in velocity profile, resulting in higher mobility compared to dry flows. Experimental results also reveal the influence of source volume on flow behavior.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2022)
Article
Mechanics
S. Athani, B. Metzger, Y. Forterre, R. Mari
Summary: We investigated the transient dynamics of a sheared suspension of neutrally buoyant particles in pressure-imposed rheology configuration. The results showed that the early stress response of the suspension may differ strongly from the prediction of the suspension balance model based on the steady-state rheology. A two-phase model incorporating the Reynolds-like dilatancy law was able to capture the suspension dilation/compaction quantitatively. The study also revealed that the early stress response of the suspension is non-local, with a non-local length scale that scales with the particle size and diverges algebraically at jamming.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Engineering, Environmental
Yaspal Sundriyal, Vipin Kumar, Firoz Khan, Mohit Kumar Puniya, Sameeksha Kaushik, Neha Chauhan, Dhirendra Singh Bagri, Naresh Rana
Summary: Floods in the Himalayas, particularly in the NW Himalaya, are increasing due to climate change. Two major flood events in Uttarakhand, NW Himalaya, have resulted in over 6000 deaths in the past decade. This study investigates the potential impact of floods on a riverbank slope and evaluates the stability and debris flow runout during extreme rainfall. The results indicate that the slope material may displace forward by approximately 0.12-0.4 m, and the potential debris flow may exert pressure on the retaining wall up to 150 k Pa. The potential flood may strike the riverbank with a velocity of 10 +/- 2 m/s and a stream power of 0.2 +/- 0.1 M N/m-s, which is three times higher than the resistance of the retaining wall.
BULLETIN OF ENGINEERING GEOLOGY AND THE ENVIRONMENT
(2023)
Article
Geosciences, Multidisciplinary
Yao Shunyu, Nazir Ahmed Bazai, Tang Jinbo, Jiang Hu, Yi Shujian, Zou Qiang, Tashfain Ahmed, Guo Jian
Summary: This study analyzed the impact of topography on the movement process of a debris flow in Wujia Gully, China. The debris flow was found to be a typical viscous debris flow with four stages in its dynamic process, and the topography played a significant role in the formation of these stages. Additionally, Manning's resistance coefficient affected the velocity and duration of each stage.
Article
Engineering, Geological
Bei Zhang, Yu Huang
Summary: This study investigates the impact dynamics of granular flows against a baffle array and proposes a jet-based model for baffle design. The results show that the energy loss due to interparticle interaction increases with the Froude number and the hard contact of larger particles and the arching effect of debris-baffle interaction are important to impact dynamics on baffle structure.
Article
Engineering, Geological
Dongri Song, Xiaoqing Chen, Gordon G. D. Zhou, Xueqiang Lu, Guanwen Cheng, Qian Chen
Summary: This study analyzed the kinetic and dynamic behavior of debris-flow impact with varying flow regimes through laboratory tests. The interaction between debris flows and obstacles was found to increase liquefaction ratio in the impact area, resulting in a more fluid-like state of debris flow. The two analytical models were able to distinguish runup height around the threshold Froude number 3-4.
ENGINEERING GEOLOGY
(2021)
Article
Engineering, Marine
Xuesheng Qian, Zhengliang Liu, Jingping Xu
Summary: In recent years, various methods have been developed to estimate the stable impact forces of submarine debris flow on pipelines. However, existing methods overlook the physically coupled effects of plasticity, inertia, and viscosity within a single framework. This study aims to provide insights into the estimations of stable impact forces based on the theory of viscoplastic fluid dynamics. The theoretical analyses are performed based on dimensionless governing equations, and estimation methods for drag and lift forces are proposed.
Article
Mechanics
Laurent Lacaze, Joris Bouteloup, Benjamin Fry, Edouard Izard
Summary: This study investigates the collapse of a granular column in a liquid using numerical simulations, focusing on the influence of Stokes number St and the initial volume fraction phi(i) on the dynamics of the collapse. A dedicated numerical model with a discrete element method is used to provide a comprehensive description of the granular phase in dense granular flows. The research aims to characterize the dynamics of the collapse and its final deposit in relation to (St, phi(i)), as well as to describe the granular rheology and dilatancy effects based on these two dimensionless numbers.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Geological
Yuan-Jun Jiang, Xiao-Yi Fan, Li-Jun Su, Si-you Xiao, Jing Sui, Rui-Xiao Zhang, Yue Song, Zhi-Wen Shen
Summary: This paper presents a new semi-empirical impact force model focusing on the normal impact force and its point of action, with an error margin within +/- 20% compared with experimental results. In calculating the residual force generated only by the static dead zone, the static friction angle between the dead zone and the chute base should be less than the value measured under kinetic conditions. Experimental results suggest that assuming the reaction force from the chute base operates at 2/3 of the deposition length provides the best estimation for the normal impact force.
Article
Engineering, Marine
Di Mu, Lifen Chen, Dezhi Ning
Summary: This paper investigates the interaction between a three-dimensional dam-break flow and a vertical circular and square cylinder using OpenFOAM simulations. The findings have relevance and importance in coastal protections and offshore operations. The numerical model is validated against experimental measurements, and further examines the effects of geometry and impacting angle on the total impact load and flow field. The results reveal two distinct stages of the impact event and highlight the significant role of flow deflection in determining the pressure field and total force behaviors.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2023)
