Investigation of Contact Parameters of DEM Model in Flow Process

2016 ◽  
pp. 465-473
Author(s):  
X. Xiao ◽  
Y. Tan ◽  
R. Deng ◽  
S. Jiang ◽  
Wei Gao ◽  
...  
Keyword(s):  
Flow Process ◽  
Dem Model ◽  
Contact Parameters

Delayed Equilibrium Model (DEM) of Flashing Choked Flows Relevant to LOCA and Implementation in System Codes

2014 ◽  
Author(s):  
Yann Bartosiewicz ◽  
Jean-Marie Seynhaeve
Keyword(s):  
Steady State ◽  
Equilibrium Model ◽  
Nuclear Reactor ◽  
Primary Circuit ◽  
Flow Process ◽  
Moby Dick ◽  
Loss Of Coolant Accident ◽  
Nuclear Reactor Safety ◽  
Gen Iv ◽  
Dem Model

In the context of nuclear reactor safety, a pipe breach in the primary circuit is the initiator of a Loss of Coolant Accident (LOCA). The calculation of leak rates involving the discharge of water and steam mixtures plays an important role in the modeling of LOCA’s for both GEN II and GEN III reactors, and also for the Supercritical Water Reactor of GEN IV. Indeed, the flow though the breach determines the depressurisation rate of the system and the time to core uncover which in turn are of major concern for when and how different mitigation auxiliary systems will be initiated and be efficient. This paper deals with the new development of the DEM model focused on thermodynamic non-equilibrium conditions, which prevail in the flashing flow process near the critical section. This model, developed at the University of Louvain (UCL), is the 1-D Delayed Equilibrium Model (DEM) for choked or critical flow rate in steady state or quasi-steady state conditions. The DEM are assessed against experimental data such as Super Moby-Dick and BETHSY experiments done in CEA during the eighties. The DEM model has been recently implemented in the WAHA code, which is based on a two fluid 1D six equations model. The methodology can be applied to other system code (CATHARE, RELAP, etc.).

scholarly journals Simulation of the Flowability of Fresh Concrete by Discrete Element Method

2021 ◽  
Vol 7 ◽  
Author(s):  
Yue Li ◽  
Ji Hao ◽  
Caiyun Jin ◽  
Zigeng Wang ◽  
Jianglin Liu
Keyword(s):  
Friction Coefficient ◽  
Discrete Element Method ◽  
Fresh Concrete ◽  
Flow Behavior ◽  
Ring Test ◽  
Slump Test ◽  
Slump Flow ◽  
Dem Model ◽  
Flow Stage ◽  
Contact Parameters

The discrete element method (DEM) was used to establish the slump model and J-Ring model of concrete to describe the flow behavior in the slump test and J-Ring test. Then, the contact parameters of particle-particle and particle-geometry for the concrete DEM model, including restitution coefficient, rolling friction coefficient, static friction coefficient, and surface energy, were measured. In order to avoid the influence of the shape and size of the aggregate, this paper used high-precision glass spheres as the aggregate of the concrete for meso-calibration test, slump test, and J-Ring test. Comparing the simulation results of DEM model with slump test result, a very high agreement between the initial stage, the rapid flow stage, and the slow flow stage of the slump flow–time curve can be found as well as the final slump and slump flow. Moreover, similar to the slump DEM model, the DEM models of J-Ring test, V-funnel test, and U-channel test were established to study the passing ability and filling ability of concrete with outstanding accuracy. Therefore, the concrete DEM model with contact parameters and JKR model can be adopted to study the flow behavior of the fresh concrete.

MATERIAL HANDLING MACHINES AND SYSTEMS – UMI-TWINN PROJECT CONTRIBUTION

2019 ◽  
Vol 12 (1) ◽  
pp. 7-20
Author(s):  
Péter Telek ◽  
Béla Illés ◽  
Christian Landschützer ◽  
Fabian Schenk ◽  
Flavien Massi
Keyword(s):  
Material Handling ◽  
Digital Data ◽  
Flow Process ◽  
Research Directions ◽  
Scientific Excellence ◽  
Research Activities ◽  
New Research ◽  
Eu Project ◽  
The University

Nowadays, the Industry 4.0 concept affects every area of the industrial, economic, social and personal sectors. The most significant changings are the automation and the digitalization. This is also true for the material handling processes, where the handling systems use more and more automated machines; planning, operation and optimization of different logistic processes are based on many digital data collected from the material flow process. However, new methods and devices require new solutions which define new research directions. In this paper we describe the state of the art of the material handling researches and draw the role of the UMi-TWINN partner institutes in these fields. As a result of this H2020 EU project, scientific excellence of the University of Miskolc can be increased and new research activities will be started.

Predictions of contact parameters for thermally-distorted pressed joints

1989 ◽  
Author(s):  
P. O'CALLAGHAN ◽  
R. BABUS'HAQ ◽  
S. PROBERT
Keyword(s):  
Contact Parameters

Parameters Measurement for Multiphase Flow Process

2013 ◽  
Vol 39 (11) ◽  
pp. 1923 ◽  
Author(s):  
Chao TAN ◽  
Feng DONG
Keyword(s):  
Multiphase Flow ◽  
Flow Process ◽  
Parameters Measurement

Validating the MFiX-DEM Model for Flow Regime Prediction in a 3D Spouted Bed

2018 ◽  
Author(s):  
Subhodeep Banerjee ◽  
Chris Guenther ◽  
William A. Rogers
Keyword(s):  
Flow Regime ◽  
Spouted Bed ◽  
Dem Model

Gas-Water Flow Behaviour During Mutual Displacement in Porous Media

2017 ◽  
Vol 10 (1) ◽  
pp. 13-22
Author(s):  
Renyi Cao ◽  
Junjie Xu ◽  
Xiaoping Yang ◽  
Renkai Jiang ◽  
Changchao Chen
Keyword(s):  
Porous Media ◽  
Relative Permeability ◽  
Gas Storage ◽  
Fluid Distribution ◽  
Water Displacement ◽  
Phase Zone ◽  
Two Phase ◽  
Flow Process ◽  
Single Well ◽  
Mutual Displacement

During oilfield development, there exist multi-cycle gas–water mutual displacement processes. This means that a cycling process such as water driving gas–gas driving water–water driving gas is used for the operation of injection and production in a single well (such as foam huff and puff in single well or water-bearing gas storage). In this paper, by using core- and micro-pore scales model, we study the distribution of gas and water and the flow process of gas-water mutual displacement. We find that gas and water are easier to disperse in the porous media and do not flow in continuous gas and water phases. The Jamin effect of the gas or bubble becomes more severe and makes the flow mechanism of multi-cycle gas–water displacement different from the conventional water driving gas or gas driving water processes. Based on experiments of gas–water mutual displacement, the changing mechanism of gas–water displacement is determined. The results indicate that (1) after gas–water mutual displacement, the residual gas saturation of a gas–water coexistence zone becomes larger and the two-phase zone becomes narrower, (2) increasing the number of injection and production cycles causes the relative permeability of gas to increase and relative permeability for water to decrease, (3) it becomes easier for gas to intrude and the invaded water becomes more difficult to drive out and (4) the microcosmic fluid distribution of each stage have a great difference, which caused the two-phase region becomes narrower and effective volume of gas storage becomes narrower.

Mathematical Description of the Influence of the Bunker Outlet on the Grain Motion in the Microwave Convective Area

2020 ◽  
pp. 73-80
Author(s):  
Aleksey N. Vasil’yev ◽  
Andrey A. Tsymbal ◽  
Aleksey A. Vasil’yev
Keyword(s):  
Mathematical Description ◽  
Microwave Field ◽  
Convective Zone ◽  
Research Purpose ◽  
Field Zone ◽  
Flow Process ◽  
Grain Processing ◽  
Grain Flow ◽  
The Right ◽  
Processing Zone

One of the environmentaly friendly methods of drying and decontamination of grain is its processing in microwave-convective installations. The efficiency of using the microwave field depends on the uniformity of its distribution in the grain processing zone. This is provided by the design features of the microwave core and waveguides. The uniformity of grain movement in the microwave field zone is important. It is important that the grain is moved in the microwave convective zone by hydraulic movement. In this case, the grain passes through zones with different intensity of the microwave field sequentially and the grain processing is uniform. (Research purpose) The research purpose is in making a mathematical dependence of parameters of the hopper outlet on the movement of grain in the microwave convective zone. (Materials and methods) The article presents the parameters of the outlet that ensure the grain flow without forming static arches in accordance with the method of calculating outlet bins. Fluctuations in humidity for different crops of processed grain will not lead to a violation of the grain flow process. The resulting equation for changing the height of the dynamic arch, depending on its location in the height of the hopper, allows to determine the uneven flow of grain from the hopper outlet. (Results and discussion) When unloading grain, there is an uneven flow in the right and left halves of the hopper, relative to the central axis. When only one hopper is unloaded, 0.84 kilograms more wheat is unloaded from its left half than from the right. This difference leads to uneven and reduced efficiency of grain processing in the microwave-convective zone. (Conclusions) To ensure the uniformity of grain processing in the microwave convective zone, it is necessary to improve the mechanism of grain flow from the outlet of the hopper.

scholarly journals Applications of Discrete Element Method in the Research of Agricultural Machinery: A Review

Agriculture ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 425
Author(s):  
Hongbo Zhao ◽  
Yuxiang Huang ◽  
Zhengdao Liu ◽  
Wenzheng Liu ◽  
Zhiqi Zheng
Keyword(s):  
Discrete Element Method ◽  
Discrete Element ◽  
Agricultural Machinery ◽  
Design And Optimization ◽  
Design Of Agricultural Machinery ◽  
Agricultural Materials ◽  
Operational Processes ◽  
Dem Model ◽  
Agricultural Machines ◽  
Element Method

As a promising and convenient numerical calculation approach, the discrete element method (DEM) has been increasingly adopted in the research of agricultural machinery. DEM is capable of monitoring and recording the dynamic and mechanical behavior of agricultural materials in the operational process of agricultural machinery, from both a macro-perspective and micro-perspective; which has been a tremendous help for the design and optimization of agricultural machines and their components. This paper reviewed the application research status of DEM in two aspects: First is the DEM model establishment of common agricultural materials such as soil, crop seed, and straw, etc. The other is the simulation of typical operational processes of agricultural machines or their components, such as rotary tillage, subsoiling, soil compaction, furrow opening, seed and fertilizer metering, crop harvesting, and so on. Finally, we evaluate the development prospects of the application of research on the DEM in agricultural machinery, and look forward to promoting its application in the field of the optimization and design of agricultural machinery.

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