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a.study on a.justed conta.t force la.s for a.celera.ed la.ge sca.e discrete element simula.ions

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Pa.ticuology 2010年第2期8卷 161-175页

作者： Ha.a.d Kruggel-Emden Fra.tisek Stepa.ek a.te munjiza Depa.tment of Chemica. Engineering South Kensington Campus Imperial College London SW7 2AZ London UK Depa.tment of Engineering Queen Mary University of London Mile End Road E1 4NS London UK

The a.m of this work is to systema.ica.ly investiga.e the effect of the norma. force la. a.d the a.plied stiff- ness on the beha.ior of single pa.ticles a.d pa.ticle systems. a.deta.led review of the litera.ure rega.ding a.tered stiffnesses a.d their use in force la.s is provided, The effect on ma.roscopic simula.ion properties such a. conta.t numbers, velocity profiles, discha.ge ra.es a.d qua.ity of dispersion for different fra.tions of ma.imum overla. is studied in the ca.e of a.stirrer vessel a.d a.recta.gula. hopper. In order to provide further a.celera.ion beyond the limits imposed by cla.sica. force models, a.number of a.terna.ive force la.s a.e developed which ha.e a.more fa.ora.le ra.io between conta.t time a.d ma.ima. overla.. Their employment in la.ge sca.e simula.ions is investiga.ed in light of their a.plica.ility. Some of the suggested force la. modifica.ions revea. a.tificia. cha.a.teristics requiring further a.tera.ion. 2009 Chinese Society of Pa.ticuology a.d Institute of Process Engineering, Chinese a.a.emy of Sciences. Published by Elsevier B.V. a.l rights reserved.

关键词： La.ge sca.e simula.ionsConta.t force modelsDiscrete Element MethodStiffnessPa.ticle overla.

Numerica. Simula.ion of Intera.tion Between La.ina. Flow a.d Ela.tic Sheet

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Tra.sa.tions of Tia.jin University 2012年第2期18卷 85-89页

作者：许栋 munjiza a.Willia.s J J R School of Engineering a.d Ma.eria. Science Queen Mary University of London Tia.jin Key La.ora.ory of Ha.bour a.d Ocea. Engineering Tianjin University

a.numerica. simula.ion of the intera.tion between la.ina. flow with low Reynolds number a.d a.highly flexible ela.tic sheet is presented. The ma.hema.ica. model for the simula.ion includes a.three-dimensiona. finitevolume ba.ed fluid solver for incompressible viscous flow a.d a.combined finite-discrete element method for the three-dimensiona. deforma.ion of solid. a. immersed bounda.y method is used to couple the simula.ion of fluid a.d solid. It is implemented through a.set of immersed bounda.y points sca.tered on the solid surfa.e. These points provide a.deforma.le solid wa.l bounda.y for the fluid by a.ding body force to Na.ier-Stokes equa.ions. The force from the fluid is a.so obta.ned for ea.h point a.d then a.plied on the bounda.y nodes of the solid. The vortex-induced vibra.ion of the highly flexible ela.tic sheet is simula.ed with the esta.lished ma.hema.ica. model. The simula.ed results for both swing pa.tern a.d oscilla.ion frequency of the ela.tic sheet in low Reynolds number flow a.ree well with experimenta. da.a.

关键词： fluid-structure intera.tion (FSI) numerica. simula.ion immersed bounda.y method combined finite-discrete element method three-dimensiona. flow

Numerica. investiga.ion of pa.ticle sa.ta.ion in the bed-loa. regime

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Science China.Technologica. Sciences) 2014年第8期57卷 1500-1511页

作者： JI ChunNing a.TE munjiza ELDa. a.ita. XU Dong JOHN Willia.s Sta.e Key La.ora.ory of Hydra.lic Engineering Simula.ion a.d Sa.ety Tianjin University School of Engineering & Ma.eria.s Science Queen MaryUniversity of London

This pa.er numerica.ly investiga.es pa.ticle sa.ta.ion in a.turbulent cha.nel flow ha.ing a.rough bed consisting of 2–3 la.ers of densely pa.ked *** this study,we combined three the sta.e-of-the-a.t technologies,i.e.,the direct numerica. simula.ion of turbulent flow,the combined finite-discrete element modelling of the deforma.ion,movement a.d collision of the pa.ticles,a.d the immersed bounda.y method for the fluid-solid *** we verify our code by compa.ing the flow a.d pa.ticle sta.istica. fea.ures with the published da.a.a.d then present the hydrodyna.ic forces a.ting on a.pa.ticle together with the pa.ticle coordina.es a.d velocities,during a.typica. *** found strong correla.ion between the a.ruptly decrea.ing pa.ticle strea.-wise velocity a.d the increa.ing vertica. velocity a. collision,which indica.es tha. the continuous sa.ta.ion of la.ge gra.n-size pa.ticles is controlled by collision pa.a.eters such a. pa.ticle incident a.gle,loca. rough bed pa.king a.ra.gement,a.d pa.ticle density,*** physica. process is different from tha. of pa.ticle entra.nment in which turbulence coherence structures pla. a. importa.t *** distribution functions of severa. importa.t sa.ta.ion pa.a.eters a.d the rela.ionships between them a.e *** results show tha. the sa.ta.ing pa.ticles hitting the windwa.d side of the bed pa.ticles a.e more likely to bounce off the rough bed tha. those hitting the *** on the a.ove findings,sa.ta.ion mecha.isms of la.ge gra.n-size pa.ticles in turbulent cha.nel flow a.e presented.

关键词： pa.ticle sa.ta.ion bed-loa. regime hydrodyna.ic forces turbulent cha.nel flow

Study on the pa.ked volume a.d the void ra.io of idea.ized huma. red blood cells using a.?nite-discrete element method

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a.plied Ma.hema.ics a.d Mecha.ics(English Edition) 2019年第5期40卷 737-750页

作者： Dong XU Chunning JI a.munjiza E.Ka.IVIOTIS E.a.ITa. J.WILLa.S Sta.e Key La.ora.ory of Hydra.lic Engineering Simula.ion a.d Sa.ety Tianjin University School of Engineering & Ma.eria. Science Queen Mary University of London Fa.ulty of Engineering a.d Technology Cyprus University of Technology

Numerica. simula.ions a.e performed to exa.ine the pa.king beha.ior of huma. red blood cells(RBCs). a.combined ?nite-discrete element method(FDEM) is utilized, in which the RBCs a.e modeled a. no-friction a.d no-a.hesion solid bodies. The pa.ked volume a.d the void ra.io of a.la.ge number of ra.domly pa.ked RBCs a.e cla.i?ed,a.d the effects of the RBC sha.e, the mesh size, the cell number, a.d the conta.ner size a.e investiga.ed. The results show tha. the pa.ked huma. RBCs with norma. sha.e ha.e a.void ra.io of 28.45%, which is slightly higher tha. tha. of the ?a. or thick cells used in this study. Such informa.ion is bene?cia. to the further understa.ding on the geometric fea.ures of huma. RBCs a.d the resea.ch on RBC simula.ions.

关键词： red blood cell (RBC) void ra.io pa.ked volume discrete element method

Spa.e decomposition ba.ed pa.a.leliza.ion solutions for the combined finiteediscrete element method in 2D

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Journa. of Rock Mecha.ics a.d Geotechnica. Engineering 2014年第6期6卷 607-615页

作者： T.Luka. G.G.Schia.a.D'a.ba.o a.munjiza School of Engineering a.d Ma.eria.s Science Queen Mary University of LondonUK

The combined finiteediscrete element method （FDEM） belongs to a.fa.ily of methods of computa.iona.mecha.ics of discontinua. The method is suita.le for problems of discontinua. where pa.ticles a.edeforma.le a.d ca. fra.ture or fra.ment. The a.plica.ions of FDEM ha.e sprea. over a.number of disciplinesincluding rock mecha.ics, where problems like mining, minera. processing or rock bla.ting ca.be solved by employing FDEM. In this work, a.novel a.proa.h for the pa.a.leliza.ion of two-dimensiona.（2D） FDEM a.ming a. clusters a.d desktop computers is developed. Dyna.ic doma.n decompositionba.ed pa.a.leliza.ion solvers covering a.l a.pects of FDEM ha.e been developed. These ha.e beenimplemented into the open source Y2D softwa.e pa.ka.e a.d ha.e been tested on a.PC cluster. Theovera.l performa.ce a.d sca.a.ility of the pa.a.lel code ha.e been studied using numerica. exa.ples. Theresults obta.ned confirm the suita.ility of the pa.a.lel implementa.ion for solving la.ge sca.e problems. 2014 Institute of Rock a.d Soil Mecha.ics, Chinese a.a.emy of Sciences. Production a.d hosting byElsevier B.V. a.l rights reserved.

关键词： Pa.a.leliza.ion Loa. ba.a.cing PC cluster Combined finiteediscrete element method(FDEM)

Modelling of ma.sive pa.ticula.es for brea.wa.er engineering using coupled FEMDEM a.d CFD

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Pa.ticuology 2008年第6期6卷 572-583页

作者： John-Pa.l La.ha.a.a.tonio munjiza Julia. Mindel Jia.sheng Xia.g Roma.n Guises Xa.ier Ga.cia.Chris Pa.n Gera.d Gorma. Ma.thew Piggott Depa.tment of Ea.th Science a.d Engineering Imperial College London UK Depa.tment of Engineering Queen Mary London University London UK

The sea.a.d slope of ma.y brea.wa.ers consists of thousa.ds of interlocking units of rock or concrete comprising a.ma.sive gra.ula. system of la.ge elements ea.h weighing tens of tonnes. The dumped qua.ry ma.eria.s in the core a.e protected by progressively coa.ser pa.ticula.es. The outer a.mour la.er of freely pla.ed units is intended to both dissipa.e wa.e energy a.d rema.n structura.ly sta.le a. strong flows a.e dra.n in a.d out of the pa.ticula.e core. Design guida.ce on the ma.s a.d sha.e of these units is ba.ed on empirica. equa.ions derived from sca.ed physica. model tests. The ma.n fa.lure mode for a.mour la.ers exposed to severe storms is hydra.lic insta.ility where the a.mour units of concrete or rock a.e subjected to uplift a.d dra. forces which ca. in turn lea. to rocking, displa.ement a.d collisions sufficient to ca.se brea.a.e of units. Recently invented a.mour unit designs ma.ing up such gra.ula. la.ered system owe much of their success to the desira.le emergent properties of interlock a.d porosity a.d how these combine with individua. unit structura. strength a.d inertia. ma.s. Funda.enta. understa.ding of the forces governing such wa.e-structure intera.tion rema.ns poor. We use discrete element a.d combined finite-discrete element methods to model the gra.ula. solid skeleton of ra.domly pa.ked units coupled to a.CFD code which resolves the wa.e dyna.ics through a. interfa.e tra.king technique. The CFD code exploits severa. methods including a.compressive a.vection scheme, node movement, a.d genera. mesh optimiza.ion. We provide the engineering context a.d report progress towa.ds the numerica. modelling of insta.ility in these ma.sive gra.ula. systems.

关键词： Modelling DEM Wa.e-structure intera.tion a.mour units Brea.wa.er

基于联合有限元-离散元的混凝土重力坝破坏三维仿真模拟

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计算力学学报 2017年第1期34卷 49-56页

作者：申振东许栋白玉川及春宁 a.te munjiza 天津大学水利工程仿真与安全国家重点试验室天津300072 伦敦玛丽女王大学工程与材料科学学院

水利工程中混凝土重力坝在地震等作用下的三维破坏形式以及破坏过程对大坝安全影响重大。本文建立了固体材料的联合有限元-离散元(Combined Finite-Discrete Element)三维数学模型,并引入Single/Smea.ed断裂损伤模型,模拟混凝土材料的... 详细信息

水利工程中混凝土重力坝在地震等作用下的三维破坏形式以及破坏过程对大坝安全影响重大。本文建立了固体材料的联合有限元-离散元(Combined Finite-Discrete Element)三维数学模型,并引入Single/Smea.ed断裂损伤模型,模拟混凝土材料的破坏。数学模型经验证后,用于地震作用下混凝土重力坝破坏的三维数值模拟,结果表明,联合有限元-离散元方法能够有效模拟坝体的破坏模式和破坏阈值条件,且具有将坝体连续变形与不连续断裂有机结合的优点。通过一系列数值模拟工况的对比,分析了模型网格分辨率对破坏条件、破坏模式以及程序计算效率的影响,研究结果能够为大坝的抗震设计提供有价值的参考。

关键词：混凝土重力坝联合有限元-离散元 Single/Smea.ed破坏模型三维模拟