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이슬기(S.G. Lee),이승수(S. Lee),이주용(J.Y. Lee),엄정아(J.A. Um),이원호(W.H. Yi) 한국전산유체공학회 2020 한국전산유체공학회지 Vol.25 No.4
This paper presents the computational analysis of debris flow using multi-phase modeling and resulting impact force on the structure. The mixture of soil and water was modeled as slurry phase for various water content controlled by volume concentration of each material. Unsteady flow was solved for incompressible fluid in 3D domain and volume of fluid (VOF) method was introduced to trace the boundary between the slurry and the ambient air. Due to the shear thinning characteristics of slurry, nonlinear viscosity model was implemented. In order to verify the present method, the numerical computations were carried out for the experimental setup with the sloped channel employed in a previous study. As expected and shown in the previous experimental study, the greater impact force on the measuring plate was obtained for the larger angle of slope. In addition, the maximum impact force occurred much faster for the slurry with the higher water content. The comparison between the experimental results and the present computation shows a good agreement. It was also found that the critical water content at which the debris starts to flow was 35% at an inclination of 50° and 40% to 40°. As the result, it is expected that present method can be used to calculate the impact force of the debris flows on the structures, and can further be used for damage prediction and reduction.
토사 물성의 불확실성을 고려한 토석류 퇴적특성 수치해석 연구
이슬기(S.G. Lee),이승수(S. Lee) 한국전산유체공학회 2021 한국전산유체공학회지 Vol.26 No.4
Recent climate change often causes heavy rainfall inducing abrupt debris flow that results in many forms of damage and loss. There have been extensive investigations on the characteristics of debris flow mainly by experimental methods. However, the results of the experimental studies always include uncertainly because the material properties of debris flow such as water content and composition of soil used in the studies varies to some extent. In order to identify the uncertainty, this study employs the 3D Navier-Stokes equation with the volume of fluid (VOF) method in order to consider multi-phase materials, and the nonlinear viscous model was implemented. Both variations of water contents and nonlinear viscosity were considered and the results of deposition features were compared with previous studies. The results show that the deposition width of the debris flow tends to decrease as the volumetric water content of the debris flow increases, and increase as the free parameter τ<SUB>00</SUB> used to estimate the yield stress increases. It is expected that the results of this study on the uncertainty of the material properties of the debris flow can present the range of affected region and that it can be used for the study of the impact load on the downstream field.