scholarly journals Impact Force of a Geomorphic Dam-Break Wave against an Obstacle: Effects of Sediment Inertia

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 232
Author(s):  
Cristiana Di Cristo ◽  
Massimo Greco ◽  
Michele Iervolino ◽  
Andrea Vacca
Keyword(s):  
Impact Force ◽  
Dam Break ◽  
Solid Particles ◽  
Physical Damage ◽  
Two Phase ◽  
Rigid Obstacle ◽  
Shallow Water Approximation ◽  
Set Up ◽  
The Impact

The evaluation of the impact force on structures due to a flood wave is of utmost importance for estimating physical damage and designing adequate countermeasures. The present study investigates, using 2D shallow-water approximation, the morphodynamics and forces caused by a dam-break wave against a rigid obstacle in the presence of an erodible bed. A widely used coupled equilibrium model, based on the two-dimensional Saint–Venant hydrodynamic equations combined with the sediment continuity Exner equation (SVEM), is compared with a more complex two-phase model (TPM). Considering an experimental set-up presented in the literature with a single rigid obstacle in a channel, two series of tests were performed, assuming sand or light sediments on the bottom. The former test is representative of a typical laboratory experiment, and the latter may be scaled up to a field case. For each test, two different particle diameters were considered. Independently from the particle size, it was found that in the sand tests, SVEM performs similarly to TPM. In the case of light sediment, larger differences are observed, and the SVEM predicts a higher force of about 26% for both considered diameters. The analysis of the flow fields and the morphodynamics shows these differences can be essentially ascribed to the role of inertia of the solid particles.

scholarly journals Research and Improvement of the Hydraulic Suspension System for a Heavy Hydraulic Transport Vehicle

2020 ◽  
Vol 10 (15) ◽  
pp. 5220 ◽  
Author(s):  
Jianjun Wang ◽  
Jingyi Zhao ◽  
Wenlei Li ◽  
Xing Jia ◽  
Peng Wei
Keyword(s):  
Mathematical Model ◽  
Nonlinear System ◽  
Ride Comfort ◽  
Impact Force ◽  
Suspension System ◽  
Experimental Results ◽  
Hydraulic Transport ◽  
Transport Vehicle ◽  
Set Up ◽  
The Impact

In order to ensure the ride comfort of a hydraulic transport vehicle in transportation, it is important to account for the effects of the suspension system. In this paper, an improved hydraulic suspension system based on a reasonable setting of the accumulator was proposed for a heavy hydraulic transport vehicle. The hydraulic transport vehicle was a multi-degree nonlinear system, and the establishment of an appropriate vehicle dynamical model was the basis for the improvement of the hydraulic suspension system. The hydraulic suspension system was analyzed, and a mathematical model of the hydraulic suspension system with accumulator established and then analyzed. The results revealed that installing the appropriate accumulator can absorb the impact pressure on the vehicle, while a hydraulic suspension system with an accumulator can be designed. Further, it was proved that a reasonable setting for the accumulator can reduce the impact force on the transport vehicle through simulation, and the optimal accumulator parameters can be obtained. Finally, an experiment in the field was set up and carried out, and the experimental results presented to prove the viability of the proposed method.

Solid–liquid two-phase flow and erosion calculation of butterfly valves at small opening based on DEM method

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Benliang Xu ◽  
Zuchao Zhu ◽  
Zhe Lin ◽  
Dongrui Wang
Keyword(s):  
Peer Review ◽  
Two Phase Flow ◽  
Solid Particles ◽  
Phase Flow ◽  
Butterfly Valve ◽  
Two Phase ◽  
Content Type ◽  
Small Opening ◽  
Solid Liquid ◽  
The Impact

Purpose The study aims to decrease the effect of solid particles on a butterfly valve, which will cause seal failure and leakage, providing a reference for anti-wear design. Design/methodology/approach In this paper, computational fluid dynamics discrete element method (CFD-DEM) simulation was conducted to study the solid–liquid two-phase flow characteristics and erosion characteristics of a butterfly valve with a different opening. Findings Abrasion at 10% opening is affected by high-speed jets in upper and lower parts of the pipeline, where the erosion is intense. The impact of the jet on the upper part of 20% opening begins to weaken. With the top backflow vortex disappearing, the effect of lower jet is enhanced. Meanwhile, the bottom backflow vortex phenomenon is obvious, and the abrasion position moves downward. At 30% opening, the velocity is further weakened, and the circulation effect of lower flow channel is more obvious than that of the upper one. Originality/value It is the first time to use DEM to investigate the two-phase flow and erosion characteristics at a small opening of a butterfly valve, considering the effect of inter-particle collision. Therefore, this study carries on the thorough analysis and discussion. At the same opening degree, with increasing of the particle size, the abrasion of valve frontal surface increases when the size is less than 150 µm and decreases when it is greater than 150 µm. For the valve backflow surface, this boundary value becomes 200 µm. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0264/

Study on Polyvinyl Alcohol Hydrogel Materials for Improving the Performance of Artificial Articular Cartilage

2013 ◽  
Vol 703 ◽  
pp. 29-32 ◽  
Author(s):  
Hou Jiang Yuan ◽  
Zhou Jian Wei ◽  
Xia Zhen Yu
Keyword(s):  
Articular Cartilage ◽  
Polyvinyl Alcohol ◽  
Impact Force ◽  
Biomechanical Properties ◽  
Research Progress ◽  
Cartilage Defects ◽  
Human Articular Cartilage ◽  
The Impact ◽  
Articular Cartilage Defects

Polyvinyl alcohol hydrogel has compatibility and biomechanical properties of human articular cartilage similar and good biological. The implantation in the human body can replace part of articular cartilage, which plays the role of bearing and alleviate the impact force. It has the prospect of clinical application. This paper introduces the research progress of polyvinyl alcohol hydro-gel materials. And compared with the characteristics of articular cartilage, clarify the possibility of repair of articular cartilage defects of the materials.

scholarly journals Dynamic Response Analysis of Retaining Dam under the Impact of Solid-Liquid Two-Phase Debris Flow Based on the Coupled SPH-DEM-FEM Method

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Bailong Li ◽  
Changming Wang ◽  
Yanying Li ◽  
Yiao Liu ◽  
Nan Jiang ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Debris Flow ◽  
Impact Force ◽  
Time History ◽  
Impact Behavior ◽  
Response Analysis ◽  
Two Phase ◽  
Fem Method ◽  
Solid Liquid ◽  
The Impact

Based on the coupled SPH-DEM-FEM numerical method, this paper analyzes the dynamic interaction of solid debris flow particle-liquid debris flow slurry-retaining dam in order to explore the dynamic response of retaining dam under the impact of the solid-liquid two-phase debris flow and delves into the process of the debris flow impact on the dam, the impact force of debris flow, and the elastic-plastic time-history characteristics of the dam under different slopes of trapezoidal grooves. The calculation results show that the coupled SPH-DEM-FEM method can vividly simulate the impact behavior of the solid-liquid two-phase debris flow on the dam, reproduce the impact, climbing, and siltation in the process of the debris flow impact; the dynamic time-history curve of the retaining dam is consistent with the law of the literature, and the result of the debris flow impact force obtained is close to that of the empirical formula. Moreover, this paper studies the impact force distribution of the debris flow impact process. The results have a certain reference value for the study of the dynamic response of the retaining dam under the impact of the solid-liquid two-phase debris flow and the engineering design of the debris flow-retaining dam.

The role of Latin America in the world sugar trade

2010 ◽  
pp. 103-108
Author(s):  
Leonardo Bichara Rocha
Keyword(s):  
Latin America ◽  
Latin American ◽  
Central American ◽  
Relative Growth ◽  
Raw Sugar ◽  
Sugar Trade ◽  
Set Up ◽  
The Impact ◽  
Sugar Exports

This paper reviews the major changes and trends in the raw and white sugar trade flows involving Latin American exporters and their partners. The paper assesses the recent absolute and relative growth in the volume of sugar exports from Brazil (the region’s and the world’s dominant exporter) and other major regional exporters such as Guatemala, Cuba, Colombia, Mexico and Argentina. Latin America has emerged as the world’s largest net sugar exporting region. Significant volumes of raw sugar of Latin American origin are now used by a large number of new destination refineries which have been set up in the Middle East and Asia. Indeed, the share of Latin America in global raw sugar exports has increased from 62.8% on average between 2002 and 2004 to 67.3% on average between 2006 and 2008. This paper also evaluates the impact of preferential trade agreements, including the CAFTA and the EPA, for Central American and Caribbean sugar exporters, as well as the implications of NAFTA for Mexico’s sugar. Finally, the paper discusses the potential gains and benefits that diversification into ethanol and cogeneration have provided to the major Latin American sugarcane industries.

Dynamic Impact Over a Subsurface Crack: Applications to the Dynamic Tear Test

1985 ◽  
Vol 52 (2) ◽  
pp. 287-290 ◽  
Author(s):  
L. M. Brock ◽  
M. Jolles ◽  
M. Schroedl
Keyword(s):  
Fracture Toughness ◽  
Impact Force ◽  
Wave Pattern ◽  
Subsurface Crack ◽  
Transverse Impact ◽  
Dynamic Impact ◽  
Reflected Waves ◽  
The Impact ◽  
Insight Into

Dynamic fracture is often studied by means of the dynamic tear (DT) test, which involves transverse impact by a mass on a beam. This process generates a complicated elastic wave pattern in the beam which, however, consists of two wave types: impact waves and reflected waves. The former are the compression wave radiating from the impact line and its diffractions at the notch end, while the latter are all waves originated by reflections from the beam surfaces. To gain insight into the role of specific waveforms in generating the fracture at the notch end in this process, the effects of the impact waves on the dynamic notch end stress field is studied. For both an idealized and an experimentally determined impact force, these waves are shown to initially place the notch end in compression. Moreover, even when a tensile stress state is eventually achieved, the stress intensity factor levels lie well below experimentally determined fracture toughness values. These results suggest that reflected waves generate the fracture, which agrees with experimental evidence.

Design of Experiment, Approximate Model and Optimization of a Muzzle Brake

2011 ◽  
Vol 295-297 ◽  
pp. 2563-2567
Author(s):  
Kun Jiang ◽  
Hao Wang
Keyword(s):  
Numerical Simulation ◽  
Impact Force ◽  
Latin Hypercube Sampling ◽  
Approximate Model ◽  
Shape Parameters ◽  
Analysis Process ◽  
Surface Method ◽  
Brake Performance ◽  
Set Up ◽  
The Impact

The approximate model of the muzzle brake performance was set up and evaluated to simplify the analysis process. LHS(Latin Hypercube Sampling) and numerical simulation of inviscid muzzle flow field were applied to obtain some samples of the muzzle brake performance. The performance was weighted with the impact force on the muzzle brake. Then RSM(Response Surface Method) was adopted to get the approximate model of the muzzle brake performance to establish a mapping of muzzle brake shape parameters and the impact force. In the end GA(Genetic Algorithm) was applied to perform the optimization of the muzzle brake shape parameters with the approximate model.

scholarly journals Hospitals

2008 ◽  
Vol 1 (2) ◽  
Author(s):  
Judith Godden
Keyword(s):  
Hospital Care ◽  
Striking Feature ◽  
Level Of Care ◽  
Large Hospital ◽  
Hospital Governance ◽  
European Institutions ◽  
Role Of The State ◽  
Set Up ◽  
The Impact

A hospital was one of the first European institutions set up in Australia in 1788. The aim in this article is to summarise the ensuring events, and particularly to demonstrate how hospitals have dramatically changed. One theme is to clarify the nature of convict hospitals and the low level of care expected in charity hospitals during the nineteenth and early twentieth centuries. Other themes are the impact of medical innovations, and the strong and increasingly interventionist role of the state in hospital governance. More recently, a theme has been the closure of small hospitals and the development of large hospital complexes. Throughout, the role of nurses has been crucial as they have provided the bulk of hospital care. Hospitals have always been plagued by scandals but the striking feature throughout their history in Sydney is the strength of the demand for hospital care.

scholarly journals Dissection of Genetic Factors Modulating Fetal Growth in Cattle Indicates a Substantial Role of the Non-SMC Condensin I Complex, Subunit G (NCAPG) Gene

Genetics ◽  
2009 ◽  
Vol 183 (3) ◽  
pp. 951-964 ◽  
Author(s):  
Annett Eberlein ◽  
Akiko Takasuga ◽  
Kouji Setoguchi ◽  
Ralf Pfuhl ◽  
Krzysztof Flisikowski ◽  
...  
Keyword(s):  
Fetal Growth ◽  
Significant Quantitative Trait Locus ◽  
Postnatal Life ◽  
Genetic Components ◽  
Genome Association ◽  
Whole Genome Association ◽  
Trait Locus ◽  
Set Up ◽  
The Impact

The increasing evidence of fetal developmental effects on postnatal life, the still unknown fetal growth mechanisms impairing offspring generated by somatic nuclear transfer techniques, and the impact on stillbirth and dystocia in conventional reproduction have generated increasing attention toward mammalian fetal growth. We identified a highly significant quantitative trait locus (QTL) affecting fetal growth on bovine chromosome 6 in a specific resource population, which was set up by consistent use of embryo transfer and foster mothers and, thus, enabled dissection of fetal-specific genetic components of fetal growth. Merging our data with results from other cattle populations differing in historical and geographical origin and with comparative data from human whole-genome association mapping suggests that a nonsynonymous polymorphism in the non-SMC condensin I complex, subunit G (NCAPG) gene, NCAPG c.1326T>G, is the potential cause of the identified QTL resulting in divergent bovine fetal growth. NCAPG gene expression data in fetal placentomes with different NCAPG c.1326T>G genotypes, which are in line with recent results about differential NCAPG expression in placentomes from studies on assisted reproduction techniques, indicate that the NCAPG locus may give valuable information on the specific mechanisms regulating fetal growth in mammals.

Study on the Vibrational Characteristics of a Tube Array Caused by Two-Phase Flow—Part 1: Random Vibration

1992 ◽  
Vol 114 (4) ◽  
pp. 472-478 ◽  
Author(s):  
T. Nakamura ◽  
K. Fujita ◽  
K. Kawanishi ◽  
N. Yamaguchi ◽  
A. Tsuge
Keyword(s):  
Random Vibration ◽  
Two Phase Flow ◽  
Impact Force ◽  
Phase Flow ◽  
Liquid Slug ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Vibrational Characteristics ◽  
Flow Part ◽  
The Impact

There are few published papers about the flow-induced vibration caused by two-phase flow. Especially, the experimental data at high-pressure and high-temperature conditions which corresponds to the practical phenomenon, are extremely few, and the mechanism of the two-phase flow-induced load acting on a tube in tube array has not yet been explained. This paper shows the experimental results about the turbulent buffeting force both by air-water two-phase flow and by steam-water flow of extreme conditions up to 5.8 MPa in pressure and 272°C in temperature, the explanation of the mechanism of this force, and the method to evaluate the response of the tube caused by two-phase flow. Here, the main source of the buffeting force by two-phase flow in slug or froth flow pattern is recognized to be the impact force caused by the intermittently rising liquid slug. The slug speed and the fluid force acting on a tube are estimated, combined with the estimation of the intermittence of the occurrence of the liquid slug rising.

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