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See detailOn the performance of an overlapping-domain parallelization strategy for Eulerian-Lagrangian Multiphysics software
Pozzetti, Gabriele UL; Besseron, Xavier UL; Rousset, Alban UL et al

in AIP Conference Proceedings (in press)

In this work, a strategy for the parallelization of a two-way CFD-DEM coupling is investigated. It consists on adopting balanced overlapping partitions for the CFD and the DEM domains, that aims to reduce ... [more ▼]

In this work, a strategy for the parallelization of a two-way CFD-DEM coupling is investigated. It consists on adopting balanced overlapping partitions for the CFD and the DEM domains, that aims to reduce the memory consumption and inter-process communication between CFD and DEM. Two benchmarks are proposed to assess the consistency and scalability of this approach, coupled execution on 252 cores shows that less than 1\% of time is used to perform inter-physics data exchange. [less ▲]

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See detailMultiscale model of sintering: diffusion and plastic flow
Kabore, Brice Wendlassida UL; Peters, Bernhard UL

Scientific Conference (2017, September 27)

Impacting particles or static aggregated particles at high temperature may undergo a permanent change of shape modifying the microstructure. Two particles in contact can develop some bonds within sub ... [more ▼]

Impacting particles or static aggregated particles at high temperature may undergo a permanent change of shape modifying the microstructure. Two particles in contact can develop some bonds within sub-second time. This fast sintering force in the particular case of the snow contribute to the rheological behavior and grain rearrangement [1]. Understanding the kinetics of sintering in granular material is of great importance in some engineering applications. For decades, diffusional processes have received more attention in investigations related to the mechanisms behind sintering [2]. Some works have suggested that the plastic flow might be neglected in sintering process for stresses are not high enough to cause dislocation. However, some studies have showed that stresses experienced in fine particles necks can be high enough and even lead to plasticity driven sintering. The importance of each mechanism in the sintering process may lie in the temporal and spatial scale of interest. Increasing importance is being accorded to the role of plastic flow in sintering. however, several investigations have proved that the conventional plasticity theory may fail to predict plastic activity at micro-scale, The objective of this work is to develop adequate computational model that includes instantaneous and time-dependent plastic flow at micro-scale. We aim at extending existing models of sintering and plasticity to cope with multiple spatial and temporal scales simulations using Extended Discrete Element Method. The numerical results are compare to experimental data on snow. [less ▲]

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See detailIntroduction to Detection of Non-Technical Losses using Data Analytics
Glauner, Patrick UL; Meira, Jorge Augusto UL; State, Radu UL et al

Scientific Conference (2017, September)

Electricity losses are a frequently appearing problem in power grids. Non-technical losses (NTL) appear during distribution and include, but are not limited to, the following causes: Meter tampering in ... [more ▼]

Electricity losses are a frequently appearing problem in power grids. Non-technical losses (NTL) appear during distribution and include, but are not limited to, the following causes: Meter tampering in order to record lower consumptions, bypassing meters by rigging lines from the power source, arranged false meter readings by bribing meter readers, faulty or broken meters, un-metered supply, technical and human errors in meter readings, data processing and billing. NTLs are also reported to range up to 40% of the total electricity distributed in countries such as Brazil, India, Malaysia or Lebanon. This is an introductory level course to discuss how to predict if a customer causes a NTL. In the last years, employing data analytics methods such as data mining and machine learning have evolved as the primary direction to solve this problem. This course will compare and contrast different approaches reported in the literature. Practical case studies on real data sets will be included. Therefore, attendees will not only understand, but rather experience the challenges of NTL detection and learn how these challenges could be solved in the coming years. [less ▲]

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See detailComparing Broad-Phase Interaction Detection Algorithms for Multiphysics DEM Applications
Rousset, Alban UL; Mainassara Chekaraou, Abdoul Wahid UL; Liao, Yu-Chung UL et al

Scientific Conference (2017, September)

Collision detection is an ongoing source of research and optimization in many fields including video-games and numerical simulations [6, 7, 8]. The goal of collision detection is to report a geometric ... [more ▼]

Collision detection is an ongoing source of research and optimization in many fields including video-games and numerical simulations [6, 7, 8]. The goal of collision detection is to report a geometric contact when it is about to occur or has actually occurred. Unfortunately, detailed and exact collision detection for large amounts of objects represent an immense amount of computations, naivly n 2 operation with n being the number of objects [9]. To avoid and reduce these expensive computations, the collision detection is decomposed in two phases as it shown on Figure 1: the Broad-Phase and the Narrow-Phase. In this paper, we focus on Broad-Phase algorithm in a large dynamic three-dimensional environment. We studied two kinds of Broad-Phase algorithms: spatial partitioning and spatial sorting. Spatial partitioning techniques op- erate by dividing space into a number of regions that can be quickly tested against each object. Two types of spatial partitioning will be considered: grids and trees. The grid-based algorithms consist of a spatial partitioning processing by dividing space into regions and testing if objects overlap the same region of space. And this reduces the number of pairwise to test. The tree-based algorithms use a tree structure where each node spans a particular space area. This reduces the pairwise checking cost because only tree leaves are checked. The spatial sorting based algorithm consists of a sorted spatial ordering of objects. Axis-Aligned Bounding Boxes (AABBs) are projected onto x, y and z axes and put into sorted lists. By sorting projection onto axes, two objects collide if and only if they collide on the three axes. This axis sorting reduces the number of pairwise to tested by reducing the number of tests to perform to only pairs which collide on at least one axis. For this study, ten different Broad-Phase collision detection algorithms or framework have been considered. The Bullet [6], CGAL [10, 11] frameworks have been used. Concerning the implemented algorithms most of them come from papers or given implementation [less ▲]

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See detailInvestigating Multiphase flow Behavior in Trickle Bed Reactors using eXtended Discrete Element Method (XDEM)
Baniasadi, Maryam UL; Peters, Bernhard UL

Scientific Conference (2017, May 08)

The existence of multiphase flows through packed bed of solid particles in broad spectrum of engineering disciplines such as chemical industries, petroleum engineering, wastewater treatment is undeniable ... [more ▼]

The existence of multiphase flows through packed bed of solid particles in broad spectrum of engineering disciplines such as chemical industries, petroleum engineering, wastewater treatment is undeniable. One frequently used reactor of this type is a trickle bed reactor that usually contains particulate phase of which the interstitial space is filled with gas and liquid phases. Based on the direction of the fluid flow they can be classified as cocurrent downflow trickle bed reactors, counter-current trickle bed reactors and cocurrent upflow packed bubble reactors. In these kind of problems numerical simulations can help to gain a better process understanding. In the current distribution, a numerical method so called Extended Discrete Element Method (XDEM) was applied to model multiphase flow through packed bed of solid particles which has the ability to be coupled to Computational Fluid Dynamics (CFD) through interphase momentum transfer. In this coupled solver the fluid phases are treated by CFD while the position and orientation of the particles in each CFD cell and the porosity distribution through packed bed are provided by XDEM. In order to validate the code, two important hydrodynamic parameters such as pressure drop and liquid hold up were investigated and satisfactory agreement between predicted and experimental data was achieved. The model results demonstrate enormous effect of solid particles on the deviation of fluid phases while passing through packed bed by investigating parameters such as velocity and drag force. [less ▲]

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See detailMultiscale-multiphysics approaches for engineering applications
Pozzetti, Gabriele UL; Peters, Bernhard UL

in AIP Conference Proceedings (2017), 1863(1), 180001

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See detailLes fondements de l'autonomie de la volonté en droit national et en droit européen
Kinsch, Patrick UL

in Panet, Amélie; Fulchiron, Hugues; Wautelet, Patrick (Eds.) L’autonomie de la volonté dans les relations familiales internationales (2017)

Detailed reference viewed: 21 (2 UL)
See detailApplication of the extended discrete element method (XDEM) in the melting of a single particle
Baniasadi, Mehdi UL; Baniasadi, Maryam UL; Peters, Bernhard UL

in Baniasadi, Mehdi (Ed.) Application of the extended discrete element method (XDEM) in the melting of a single particle (2016, July 19)

In this contribution, a new method referred to as Extended Discrete Element Method (XDEM) is usedto model melting of a single particle in the fluid media. The XDEM as a Lagrangian-Eulerian framework is ... [more ▼]

In this contribution, a new method referred to as Extended Discrete Element Method (XDEM) is usedto model melting of a single particle in the fluid media. The XDEM as a Lagrangian-Eulerian framework is the extension of Discrete Element Method (DEM) by considering thermodynamic state such as temperature distribution and is able to link with Computational Fluid Dynamics (CFD) for fluid phase. In order to provide more accurate results, multiscale method was used. The model is validated by comparing predicted results with existing experimental data for melting of a single ice particle in a water bath. In addition, the model has the capability to be extended to the packed bed of particles with different size and properties to produce different liquid phases. [less ▲]

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See detailCFD-XDEM FOR PREDICTING MULTIPHASE FLOW BEHAVIOR THROUGH POROUS MEDIA
Baniasadi, Maryam UL; Peters, Bernhard UL

Scientific Conference (2016, June 05)

An accurate description of fluid flow through porous media is very important to predict, design and optimize many industrial phenomena principally in condition where experimental studies are difficult to ... [more ▼]

An accurate description of fluid flow through porous media is very important to predict, design and optimize many industrial phenomena principally in condition where experimental studies are difficult to perform. In these kind of problems numerical simulations can help to gain a better process understanding. During last decades many numerical approaches mainly Finite Volume Method (FVM) were applied to model different multiphase flows containing gas, liquid and solid phases. The solid phase may treat by continuous or discrete frameworks. In the former method which is based on Eulerian framework the solid phase is considered as a continuous phase like other fluid phases while in the second method which is based on Lagrangian framework, the solid phase is considered as separate particles. In this study, the flow behavior of several incompressible isotherm phases through solid particles was modelled. The model describes the motion of fluid flows such as gas and liquid phases using continuum approach by applying Computational Fluid Dynamics (CFD) as a numerical method and the solid particles by Lagrangian framework using so-called eXtended Discrete Element Method (XDEM). XDEM is a numerical simulation framework based on classical Discrete Element Methods (DEM) extended by consideration of thermophysical states. A combination of the two numerical methods was performed through momentum and mass exchange between fluid and solid phases which is called combined continuum discrete approach. The solid phase is considered as packed solid particles. The model results demonstrate enormous effect of solid particles on deviation of fluid phases while passing through particles by testing different drag force models. This model was applied to the dripping zone of blast furnace where the liquid phases of liquid iron and slag flow downward through coke particles and gas phase ascends upwards through the shaft which is classified as a counter-current multiphase packed bed reactor. The main goal of this project is to provide a solver which is able to treat several fluid phases through porous media using combined Eulerian-Lagrangian framework by exchanging data between this two approaches. [less ▲]

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