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The dynamics of fluid flows with free surfaces and interacting with highly deformable structures is a complex problem, attracting considerable attention. The Particle Finite Element Method (PFEM) is one of the various numerical methods recently proposed in the literature to simulate this type of problems. It is a mesh‐based Lagrangian approach, particularly suited for problems with fast changes in the domain topology, since the fluid boundaries and the Fluid–Structure Interaction (FSI) interface are naturally tracked by the position of the mesh nodes. However, when nonhomogeneous boundary conditions are imposed on velocities or when there are regions where the topology varies moderately, for example, in confined portions of the fluid domain characterized by fixed boundaries, an Eulerian formulation turns out to be more convenient. To exploit the advantages of both formulations, an adaptive hybrid Lagrangian–Eulerian approach is presented in this work. According to the proposed method, nodes on the fluid free‐surface and on the FSI interface are treated as Lagrangian, while the remaining nodes can be either Eulerian or Lagrangian. Furthermore, to increase the efficiency of the method, an algorithm to automatically detect runtime the transition zone between the two kinematic descriptions is devised. To validate the proposed approach, several numerical examples are developed and their results are compared to those available in the literature. [ABSTRACT FROM AUTHOR]

This work deals with the preliminary design of glass containers to be deposited on the seabed at 2000 m depth after being filled with liquefied carbon dioxide (CO2) at a pressure of 10 MPa. The specific purpose is to provide preliminary structural analyses of the containers to be employed in a novel patent CO2 storage method called confined submarine carbon storage (CSCS). The core steps of the CSCS technology are the container manufacturing and filling with high‐pressure liquid CO2. Consequently, the container geometry, material properties and structural response are the most critical aspects in the container design. Due to the low cost and to the high stability in salty environment, glass has been identified as a suitable material for the CSCS technology. Furthermore, the high compressive resistance allows glass containers to be deposited on the seabed where the external water pressure exceeds the internal pressure of liquefied carbon dioxide. On the other hand, the limited tensile resistance of glass requires a careful shape design. The glass containers have to be designed to withstand stresses generated during their entire working life. This includes CO2 filling, the launching, the impact with the seabed and the final piling up and stacking of a huge number of containers. Finite element analyses have been performed in order to define the container shape, conjugating an acceptable storage capacity with a safe mechanical response during both the filling and deposition phases. [ABSTRACT FROM AUTHOR]

Summary: This paper concerns the rheological characterisation of liquefied sands as non‐Newtonian Bingham fluids. For this purpose, dam‐breaking laboratory tests are often executed and interpreted, offering a viable option to identify the properties of fluidised water‐soil mixtures. However, limited attention has been devoted so far to clarify what variables and measurements would allow unambiguous calibration of Bingham parameters, namely, the viscosity η and the yield stress τy. The numerical results of parametric studies based on the particle finite element method (PFEM) are critically inspected to gain deeper insight into the problem. First, it is confirmed that multiple η − τy pairs may reproduce the same experimental evidence when formed by only one measurement—usually, the post–dam‐breaking displacement of the bottom toe (tip) of the liquefied mass. Then, two alternative procedures are proposed for unambiguous identification of both η and τy: one is based on monitoring the evolving aspect ratio of the fluid mass during free, gravity‐driven flow; the other relies on a slightly different dam‐breaking test, also including impact against a rigid obstacle. In particular, the latter approach reduces the relevant duration of the test, reducing the possible influence of reconsolidation effects on the calibration of rheological parameters. [ABSTRACT FROM AUTHOR]

SUMMARY A Lagrangian numerical approach for the simulation of rapid landslide runouts is presented and discussed. The simulation approach is based on the so-called Particle Finite Element Method. The moving soil mass is assumed to obey a rigid-viscoplastic, non-dilatant Drucker-Prager constitutive law, which is cast in the form of a regularized, pressure-sensitive Bingham model. Unlike in classical formulations of computational fluid mechanics, where no-slip boundary conditions are assumed, basal slip boundary conditions are introduced to account for the specific nature of the landslide-basal surface interface. The basal slip conditions are formulated in the form of modified Navier boundary conditions, with a pressure-sensitive threshold. A special mixed Eulerian-Lagrangian formulation is used for the elements on the basal interface to accommodate the new slip conditions into the Particle Finite Element Method framework. To avoid inconsistencies in the presence of complex shapes of the basal surface, the no-flux condition through the basal surface is relaxed using a penalty approach. The proposed model is validated by simulating both laboratory tests and a real large-scale problem, and the critical role of the basal slip is elucidated. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]