@article {Latham2009, title = {{Coupled FEMDEM/Fluids for coastal engineers with special reference to armour stability and breakage}}, journal = {Geomechanics and Geoengineering}, volume = {4}, number = {1}, year = {2009}, month = {mar}, pages = {39{\textendash}53}, abstract = {Sea-level rise and increased storminess present huge challenges to coastal engineers worldwide. The seaward slope of many breakwaters and shoreline defence structures consists of thousands of interlocking units of concrete or rock making up a massive granular defence against wave attack. The units are placed freely to form an armour layer which is intended to both dissipate wave energy and remain structurally stable. Design guidance on the mass and shape of these units is based on empirical equations derived from Froude scale physical model tests. The two main failure modes for concrete armour layers are displacement (hydraulic instability) and breakage (structural instability) which are strongly coupled. Breakage mechanisms cannot all be faithfully reproduced under scaled physical models. Fundamental understanding of the forces governing such wave-structure interaction remains poor and unit breakages continue to baffle the designers of concrete armour units. This paper illustrates a range of DEM and FEMDEM methods being developed to model the granular solid skeleton of freely packed brittle units. Such discrete element methods are increasingly being used by engineers for solids modelling. They are especially powerful when coupled with a CFD model which can resolve ocean wave dynamics. The aim is to describe a framework for coupled modelling technologies applicable to coastal engineering problems. Preliminary simulation test cases, still at proof of concept stage, but based on a wealth of validation studies are presented. Thus, we report a snap-shot of progress towards a future where designers combine multi-physics numerical technology with knowledge from scalled physical models for a better understanding of wave energy turbulence, block movement, and internal stresses within armour units.}, keywords = {Breakwaters, Concrete armour units, Discrete element method, Finite element method, Fluid coupling, Ware-structure interaction}, issn = {1748-6025}, doi = {10.1080/17486020902767362}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-68149172944\&partnerID=tZOtx3y1}, author = {Latham, John-Paul and Mindel, Julian and Xiang, Jiansheng and Guises, Romain and Garcia, Xavier and Pain, Chris and Gorman, Gerard and Piggott, Matthew and Munjiza, Antonio} } @article {Latham2008a, title = {{Modelling of massive particulates for breakwater engineering using coupled FEMDEM and CFD}}, journal = {Particuology}, volume = {6}, number = {6}, year = {2008}, month = {dec}, pages = {572{\textendash}583}, abstract = {The seaward slope of many breakwaters consists of thousands of interlocking units of rock or concrete comprising a massive granular system of large elements each weighing tens of tonnes. The dumped quarry materials in the core are protected by progressively coarser particulates. The outer armour layer of freely placed units is intended to both dissipate wave energy and remain structurally stable as strong flows are drawn in and out of the particulate core. Design guidance on the mass and shape of these units is based on empirical equations derived from scaled physical model tests. The main failure mode for armour layers exposed to severe storms is hydraulic instability where the armour units of concrete or rock are subjected to uplift and drag forces which can in turn lead to rocking, displacement and collisions sufficient to cause breakage of units. Recently invented armour unit designs making up such granular layered system owe much of their success to the desirable emergent properties of interlock and porosity and how these combine with individual unit structural strength and inertial mass. Fundamental understanding of the forces governing such wave-structure interaction remains poor. We use discrete element and combined finite-discrete element methods to model the granular solid skeleton of randomly packed units coupled to a CFD code which resolves the wave dynamics through an interface tracking technique. The CFD code exploits several methods including a compressive advection scheme, node movement, and general mesh optimization. We provide the engineering context and report progress towards the numerical modelling of instability in these massive granular systems. {\textcopyright} 2008 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences.}, keywords = {Armour units, Breakwater, DEM, Modelling, Wave-structure interaction}, issn = {16742001}, doi = {10.1016/j.partic.2008.07.010}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-57049161892\&partnerID=tZOtx3y1}, author = {Latham, John-Paul and Munjiza, Antonio and Mindel, Julian and Xiang, Jiansheng and Guises, Romain and Garcia, Xavier and Pain, Chris and Gorman, Gerard and Piggott, Matthew} } @article {Latham2008, title = {{Three-dimensional particle shape acquisition and use of shape library for DEM and FEM/DEM simulation}}, journal = {Minerals Engineering}, volume = {21}, number = {11}, year = {2008}, month = {oct}, pages = {797{\textendash}805}, abstract = {Numerical simulation that will capture the complex behaviour of rock fragment systems, e.g., in mining and civil engineering, requires both the computational mechanics capability to model particle interactions between complex shapes and an associated means to represent the kind of arbitrary or angular geometry relevant to problems involving rock fragments. This paper is concerned less with the modelling and more with the representation. Here, we focus on representation geared to {\textquoteright}soft contact{\textquoteright} modelling using either combined finite-discrete element (FEM/DEM) methods, or non-spherical DEM methods such as multi-sphere approximations of irregular geometry. 3D laser ranging (LADAR) is used to capture astonishingly realistic rock aggregate geometries. We report on the work flow procedures to generate computationally meshed virtual particles for modelling. The design of a shape library and a suggested procedure for selecting virtual particles for input to FEM/DEM or DEM models is discussed together with the use of inertia moments for shape descriptors. Use of the shape library for shape descriptor analysis is also illustrated. DEM simulations of packing using irregular particles from the shape library are presented. {\textcopyright} 2008 Elsevier Ltd. All rights reserved.}, keywords = {Discrete element modelling, Gravity concentration, Mineral processing, Simulation, Sorting methods}, issn = {08926875}, doi = {10.1016/j.mineng.2008.05.015}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-50149086948\&partnerID=tZOtx3y1}, author = {Latham, John-Paul and Munjiza, Antonio and Garcia, Xavier and Xiang, Jiansheng and Guises, Romain} }