scholarly journals Dynamic Force on an Elbow Caused by a Traveling Liquid Slug

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Darcy Q. Hou ◽  
Arris S. Tijsseling ◽  
Zafer Bozkus
Keyword(s):  
Experimental Data ◽  
Impact Force ◽  
Initial Conditions ◽  
Flow Direction ◽  
Dynamic Force ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
1D Model ◽  
High Reynolds ◽  
The Impact

The impact force on an elbow induced by traveling isolated liquid slugs in a horizontal pipeline is studied. A literature review reveals that the force on the elbow is mainly due to momentum transfer in changing the fluid flow direction around the elbow. Therefore, to accurately calculate the magnitude and duration of the impact force, the slug arrival velocity at the elbow needs to be well predicted. The hydrodynamic behavior of the slug passing through the elbow needs to be properly modeled too. A combination of 1D and 2D models is used in this paper to analyze this problem. The 1D model is used to predict the slug motion in the horizontal pipeline. With the obtained slug arrival velocity, slug length, and driving air pressure as initial conditions, the 2D Euler equations are solved by the smoothed particle hydrodynamics (SPH) method to analyze the slug dynamics at the elbow. The 2D SPH solution matches experimental data and clearly demonstrates the occurrence of flow separation at the elbow, which is a typical effect of high Reynolds flows. Using the obtained flow contraction coefficient, an improved 1D model with nonlinear elbow resistance is proposed and solved by SPH. The 1D SPH results show the best fit with experimental data obtained so far.

scholarly journals Pressure evaluation during dam break using weakly compressible SPH

2019 ◽  
Vol 213 ◽  
pp. 02030
Author(s):  
Petr Jančík ◽  
Tomáš Hyhlík
Keyword(s):  
Experimental Data ◽  
Smoothed Particle Hydrodynamics ◽  
Two Dimensions ◽  
Dam Break ◽  
Kinematics And Dynamics ◽  
Sph Method ◽  
Weakly Compressible ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact

This paper presents a solution of a dam break problem in two dimensions obtained with smoothed particle hydrodynamics (SPH) method. The main focus is on pressure evaluation during the impact on the wall. The used numerical method and the way of pressure evaluation are described in detail. The numerical results of the kinematics and dynamics of the flow are compared with experimental data from the literature. The abilities and limitations of the used methods are discussed.

scholarly journals Post-Failure Dynamics of Rainfall-Induced Landslide in Oltrepò Pavese

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2555
Author(s):  
Sauro Manenti ◽  
Andrea Amicarelli ◽  
Nunziarita Palazzolo ◽  
Massimiliano Bordoni ◽  
Enrico Creaco ◽  
...  
Keyword(s):  
Impact Force ◽  
Leading Edge ◽  
Shallow Landslide ◽  
Protection Measures ◽  
Damage Prediction ◽  
Weakly Compressible ◽  
Hill Slope ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact

Prediction of landslide hazard risk at hill slope induced by intense rainfall requires the appropriate modeling of the interactions between soil and weather phenomena, leading to failure as well as a reliable prediction of post-failure dynamics. In the peculiar case of fast shallow landslides behaving like dense granular flows, a suitable modeling approach for large and rapid deformations is necessary to estimate potential related damage. The impact force exerted by the leading edge of the earth-flow on the downstream structure should be estimated for both damage prediction and design of effective protection measures. In this paper, a free open source 3D research code based on standard weakly compressible smoothed particle hydrodynamics (WCSPH) method is validated by modeling a full-scale rainfall-induced shallow landslide which occurred in Oltrepò Pavese (Northern Italy). The code allows resolving the vertical velocity gradients, potentially providing a more reliable representation of the landslide dynamics and impact force. Mechanical parameters are consistent with average soil characteristics, avoiding calibration analysis. The final landslide profile is compared with an experimental survey for model validation, showing good fit. Influence of uncertainties of geotechnical parameters on the landslide front velocity and impact force on the downstream wall is evaluated.

Numerical study on debris flow in step-pools channel using smoothed particle hydrodynamics method

2020 ◽  
Author(s):  
Shuai Li ◽  
Xiaoqing Chen ◽  
Chong Peng ◽  
Jiangang Chen
Keyword(s):  
Debris Flow ◽  
Smoothed Particle Hydrodynamics ◽  
Debris Flows ◽  
Impact Force ◽  
Numerical Study ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method ◽  
The Impact ◽  
Peak Impact Force

<p>Drainage channel with step-pool systems are widely used to control debris flow. However, the blocking of debris flow often gives rise to local damage at the steps and baffles. Hence, the estimation of impact force of debris flow is crucial for design step-pools channel. This paper presents a numerical study on the impact behavior of debris flows using SPH (Smoothed Particle Hydrodynamics) method. Some important parameters, such as the baffle shape (square, triangle, and trapezoid) and the densities of debris flows are considered to examine their influence on the impact force. The results show that the largest peak impact force is obtained at the second last baffle, rather than the first baffle. Moreover, the square baffle gives rise to the largest impact force whereas the triangle baffle bears the smallest one among the three baffles. Generally, the peak impact force increases with increasing the inflow density. However, a threshold density, beyond which the peak impact force will decrease, is suggested by the simulations. Based on the numerical results, an improved expression to predict the impact force considering the inclined angle of baffle is proposed.</p>

scholarly journals Effects of Barrier Stiffness on Debris Flow Dynamic Impact—II: Numerical Simulation

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 182
Author(s):  
Yu Huang ◽  
Xiaoyan Jin ◽  
Junji Ji
Keyword(s):  
Debris Flow ◽  
Smoothed Particle Hydrodynamics ◽  
Impact Force ◽  
Time History ◽  
Appreciable Effect ◽  
Engineering Structures ◽  
Dynamic Component ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact

The destructive and impactful forces of debris flow commonly causes local damage to engineering structures. The effect of a deformable barrier on the impact dynamics is important in engineering design. In this study, a flow–structure coupled with Smoothed Particle Hydrodynamics model was presented to investigate the effects of barrier stiffness on the debris impact. A comparison of the results of physical tests and simulation results revealed that the proposed smoothed particle hydrodynamics model effectively reproduces the flow kinematics and time history of the impact force. Even slight deflections of the deformable barrier lead to obvious attenuation of the peak impact pressure. Additionally, deformable barriers with lower stiffness tend to deform more downstream upon loading, shifting the deposited sand toward the active failure mode and generating less static earth pressure. When the debris flow has a higher frontal velocity, the impact force on the barrier is dominated by the dynamic component and there is an appreciable effect of the stiffness of the deformable barrier on load attenuation.

scholarly journals Numerical Simulation of Non-Homogeneous Viscous Debris-Flows Based on the Smoothed Particle Hydrodynamics (SPH) Method

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2314 ◽  
Author(s):  
Shu Wang ◽  
Anping Shu ◽  
Matteo Rubinato ◽  
Mengyao Wang ◽  
Jiping Qin
Keyword(s):  
Debris Flow ◽  
Water Content ◽  
Smoothed Particle Hydrodynamics ◽  
Debris Flows ◽  
Sph Method ◽  
Particle Hydrodynamics ◽  
Sph Model ◽  
Smoothed Particle ◽  
The Impact ◽  
Kinetic And Potential Energies

Non-homogeneous viscous debris flows are characterized by high density, impact force and destructiveness, and the complexity of the materials they are made of. This has always made these flows challenging to simulate numerically, and to reproduce experimentally debris flow processes. In this study, the formation-movement process of non-homogeneous debris flow under three different soil configurations was simulated numerically by modifying the formulation of collision, friction, and yield stresses for the existing Smoothed Particle Hydrodynamics (SPH) method. The results obtained by applying this modification to the SPH model clearly demonstrated that the configuration where fine and coarse particles are fully mixed, with no specific layering, produces more fluctuations and instability of the debris flow. The kinetic and potential energies of the fluctuating particles calculated for each scenario have been shown to be affected by the water content by focusing on small local areas. Therefore, this study provides a better understanding and new insights regarding intermittent debris flows, and explains the impact of the water content on their formation and movement processes.

scholarly journals Impact and Fire Modeling Considerations Employing SPH Coupling to a Dilute Spray Fire Code

2009 ◽  
Author(s):  
Alexander L. Brown
Keyword(s):  
High Speed ◽  
Good Method ◽  
Predictive Tool ◽  
Surface Deposition ◽  
Impact Surface ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Model Inadequacy ◽  
The Impact ◽  
Adequate Method

Transportation accidents and the subsequent fire present a concern. Particularly energetic accidents like an aircraft impact or a high speed highway accident can be quite violent. We would like to develop and maintain a capability at Sandia National Laboratories to model these very challenging events. We have identified Smoothed Particle Hydrodynamics (SPH) as a good method to employ for the impact dynamics of the fluid for severe impacts. SPH is capable of modeling viscous and inertial effects for these impacts for short times. We have also identified our fire code Lagrangian/Eulerian (L/E) particle capability as an adequate method for fuel transport and spray modeling. A fire code can also model the subsequent fire for a fuel impact. Surface deposition of the liquid may also be acceptably predicted with the same code. These two methods (SPH and L/E) typically employ complimentary length and timescales for the calculation, and are potentially suited for coupling given adequate attention to relevant details. Length and timescale interactions are important considerations when joining the two capabilities. Additionally, there are physical model inadequacy considerations that contribute to the accuracy of the methodology. These models and methods are presented and evaluated. Some of these concerns are detailed for a verification type scenario used to show the work in progress of this coupling capability. The importance of validation methods and their appropriate application to the genesis of this class of predictive tool are also discussed.

Modeling Hypervelocity Impacts Using Smoothed Particle Hydrodynamics

2018 ◽  
Author(s):  
M. Ganser ◽  
B. van der Linden ◽  
C. G. Giannopapa
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Large Deformations ◽  
Hypervelocity Impact ◽  
Density Fluctuations ◽  
Computational Domain ◽  
Simulation Tool ◽  
Hypervelocity Impacts ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact

Hypervelocity impacts occur in outer space where debris and micrometeorites with a velocity of 2 km/s endanger spacecraft and satellites. A proper shield design, e.g. a laminated structure, is necessary to increase the protection capabilities. High velocities result in massive damages. The resulting large deformations can hardly be tackled with mesh based discretization methods. Smoothed Particle Hydrodynamics (SPH), a Lagrangian meshless scheme, can resolve large topological changes whereas it still follows the continuous formulation. Derived by variational principles, SPH is able to capture large density fluctuations associated with hypervelocity impacts correctly. Although the impact region is locally limited, a much bigger domain has to be discretized because of strong outgoing pressure waves. A truncation of the computational domain is preferable to save computational power, but this leads to artificial reflections which influence the real physics. In this paper, hypervelocity impact (HVI) is modelled by means of basic conservation assumptions leading to the Euler equations of fluid dynamics accompanied by the Mie-Grueneisen equation of state. The newly developed simulation tool SPHlab presented in this work utilizes the discretization method smoothed particle hydrodynamics (SPH) to capture large deformations. The model is validated through a number of test cases. Different approaches are presented for non-reflecting boundaries in order to tackle artificial reflections on a computational truncated domain. To simulate an HVI, the leading continuous equations are derived and the simulation tool SPHlab is developed. The method of characteristics allows to define proper boundary fluxes by removing the inwards travelling information. One- and two-dimensional model problems are examined which show excellent absorption behaviour. An hypervelocity impact into a laminated shield is simulated and analysed and a simple damage model is introduced to model a spallation failure mode.

scholarly journals Application of Smoothed Particle Hydrodynamics (SPH) for the Simulation of Flow-like Landslides on 3D Terrains

2022 ◽  
Author(s):  
Binghui Cui ◽  
Liaojun Zhang
Keyword(s):  
Risk Assessment ◽  
Smoothed Particle Hydrodynamics ◽  
Disaster Mitigation ◽  
Sph Method ◽  
Landslide Event ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Simulation Results ◽  
Mitigation Design ◽  
The Impact

Abstract Flow-type landslide is one type of landslide that generally exhibits characteristics of high flow velocities, long jump distances, and poor predictability. Simulation of it facilitates propagation analysis and provides solutions for risk assessment and mitigation design. The smoothed particle hydrodynamics (SPH) method has been successfully applied to the simulation of two-dimensional (2D) and three-dimensional (3D) flow-like landslides. However, the influence of boundary resistance on the whole process of landslide failure is rarely discussed. In this study, a boundary algorithm considering the friction is proposed, and integrated into the boundary condition of the SPH method, and its accuracy is verified. Moreover, the Navier-Stokes equation combined with the non-Newtonian fluid rheology model was utilized to solve the dynamic behavior of the flow-like landslide. To verify its performance, the Shuicheng landslide event, which occurred in Guizhou, China, was taken as a case study. In the 2D simulation, a sensitivity analysis was conducted, and the results showed that the shearing strength parameters have more influence on the computation accuracy in comparison with the coefficient of viscosity. Afterwards, the dynamic characteristics of the landslide, such as the velocity and the impact area, were analyzed in the 3D simulation. The simulation results are in good agreement with the field investigations. The simulation results demonstrate that the SPH method performs well in reproducing the landslide process, and facilitates the analysis of landslide characteristics as well as the affected areas, which provides a scientific basis for conducting the risk assessment and disaster mitigation design.

scholarly journals Mechanism of Coup and Contrecoup Injuries Induced by a Knock-Out Punch

2020 ◽  
Vol 25 (2) ◽  
pp. 22 ◽  
Author(s):  
Milan Toma ◽  
Rosalyn Chan-Akeley ◽  
Christopher Lipari ◽  
Sheng-Han Kuo
Keyword(s):  
Cerebrospinal Fluid ◽  
Interaction Model ◽  
Brain Parenchyma ◽  
Primary Objective ◽  
Element Analysis ◽  
Knock Out ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact ◽  
The Brain

Primary Objective: The interaction of cerebrospinal fluid with the brain parenchyma in an impact scenario is studied. Research Design: A computational fluid-structure interaction model is used to simulate the interaction of cerebrospinal fluid with a comprehensive brain model. Methods and Procedures: The method of smoothed particle hydrodynamics is used to simulate the fluid flow, induced by the impact, simultaneously with finite element analysis to solve the large deformations in the brain model. Main Outcomes and Results: Mechanism of injury resulting in concussion is demonstrated. The locations with the highest stress values on the brain parenchyma are shown. Conclusions: Our simulations found that the damage to the brain resulting from the contrecoup injury is more severe than that resulting from the coup injury. Additionally, we show that the contrecoup injury does not always appear on the side opposite from where impact occurs.

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