A. Larese

Validation of the particle finite element method (PFEM) for simulation of free surface flows

Purpose – The purpose of this paper is to evaluate the possibilities of the particle finite element method for simulation of free surface flows.Design/methodology/approach – A numerical simulation of a number of examples for which experimental data are available is performed. The simulations are run using the same scale as the experiment in order to minimize errors due to scale effects. Some examples are chosen from the civil engineering field: a study of the flow over a flip bucket is analyzed for both 2D and 3D models, and the flow under a planar sluice gate is studied in 2D. Other examples, such as a 2D and 3D “dam break” with an obstacle are taken from the smooth particle hydrodynamics literature.Findings – Different scenarios are simulated by changing the boundary conditions for reproducing flows with the desired characteristics. Different mesh sizes are considered for evaluating their influence on the final solution.Originality/value – Details of the input data for all the examples studied are given...

Numerical modelling of landslide-generated waves with the particle finite element method (PFEM) and a non-Newtonian flow model

Landslide-generated impulse waves may have catastrophic consequences. The physical phenomenon is difficult to model due to the uncertainties in the kinematics of the mobilised material, and to the intrinsic complexity of the fluid-soil interaction. The Particle Finite Element Method (PFEM) [1] is a numerical scheme which has successfully been applied to fluid-structure interaction problems. It uses a Lagrangian description to model the motion of nodes (particles) in both the fluid and the solid domains (the later including soil/rock and structures). A mesh connecting the particles (nodes) is re-generated at every time step, where the governing equations are solved. Various constitutive laws are used for the sliding mass, including rigid solid and Newtonian and non-Newtonian fluids. Several examples of application are presented, corresponding both to experimental tests and to actual full-scale case studies. The results show that the PFEM can be a useful tool for analysing the risks associated to landslide phenomena, providing a good estimate to the potential hazards even for full-scale events. Copyright c

Comparison of a Material Point Method and a Galerkin Meshfree Method for the Simulation of Cohesive-Frictional Materials

The simulation of large deformation problems, involving complex history-dependent constitutive laws, is of paramount importance in several engineering fields. Particular attention has to be paid to the choice of a suitable numerical technique such that reliable results can be obtained. In this paper, a Material Point Method (MPM) and a Galerkin Meshfree Method (GMM) are presented and verified against classical benchmarks in solid mechanics. The aim is to demonstrate the good behavior of the methods in the simulation of cohesive-frictional materials, both in static and dynamic regimes and in problems dealing with large deformations. The vast majority of MPM techniques in the literatrue are based on some sort of explicit time integration. The techniques proposed in the current work, on the contrary, are based on implicit approaches, which can also be easily adapted to the simulation of static cases. The two methods are presented so as to highlight the similarities to rather than the differences from “standard” Updated Lagrangian (UL) approaches commonly employed by the Finite Elements (FE) community. Although both methods are able to give a good prediction, it is observed that, under very large deformation of the medium, GMM lacks robustness due to its meshfree natrue, which makes the definition of the meshless shape functions more difficult and expensive than in MPM. On the other hand, the mesh-based MPM is demonstrated to be more robust and reliable for extremely large deformation cases.

Numerical modelling of landslide-generated waves with the particle finite element method (PFEM) and a non-Newtonian flow model: NUMERICAL MODELLING OF LANDSLIDE-GENERATED WAVES PFEM NON-NEWTONIAN

Landslide-generated impulse waves may have catastrophic consequences. The physical phenomenon is difficult to model due to the uncertainties in the kinematics of the mobilised material, and to the intrinsic complexity of the fluid-soil interaction. The Particle Finite Element Method (PFEM) [1] is a numerical scheme which has successfully been applied to fluid-structure interaction problems. It uses a Lagrangian description to model the motion of nodes (particles) in both the fluid and the solid domains (the later including soil/rock and structures). A mesh connecting the particles (nodes) is re-generated at every time step, where the governing equations are solved. Various constitutive laws are used for the sliding mass, including rigid solid and Newtonian and non-Newtonian fluids. Several examples of application are presented, corresponding both to experimental tests and to actual full-scale case studies. The results show that the PFEM can be a useful tool for analysing the risks associated to landslide phenomena, providing a good estimate to the potential hazards even for full-scale events. Copyright c