A fully explicit fluid-structure interaction approach based on PFEM and FEM

The numerical simulation of fluid-structure interaction (FSI) problems involving free-surfaces is of great interest in many engineering applications. Particle-based methods, like PFEM, are particularly suited for the analysis of free-surface flows and fluid-structure interaction with large displacements of the interface. In the current work, a staggered approach for the solution of the FSI problem is proposed. The fluid domain is discretized with an explicit Particle Finite Element Method (PFEM) while the solid domain with a standard Finite Element Method (FEM). The weakly compressible formulation of fluid flow, originally proposed in for the PFEM, allows for a fully explicit solution scheme. Thanks to the Lagrangian formulation, the free surface is directly defined by the current position of the particles, while the governing equations are imposed like in standard FEM. When the mesh becomes too distorted, a fast remeshing algorithm is used to redefine the connectivities. The structural domain is instead analyzed with a standard commercial explicit FEM (SIMULIA Abaqus\Explicit). The coupling between the fluid and solid domains is treated with the GC Domain Decomposition approach. On each subdomain the problem is solved independently and then the two solutions are linked at the interface using a Lagrange multiplier technique. The proposed method allows for different time-steps in the two subdomains and for non-conforming meshes at the interfaces between the solid and fluid domains. Moreover, this approach allows for an explicit coupling, without iterations, between the two subdomains. 2D test-cases will be presented to validate the proposed coupling technique. The explicit scheme for both the fluid and solid subdomains, together with the explicit treatment of the coupling, makes this method appealing for applications in a variety of engineering problems with fast dynamics and/or a high degree of non-linearity

A fully explicit fluid-structure interaction approach based on the PFEM

The efficient numerical simulation of fluid-structure interaction (FSI) problems is of growing interest in many engineering fields. In the present work, a staggered approach for the solution of the FSI problem is proposed. The fluid domain is discretized with an explicit Particle Finite Element Method (PFEM) while the solid domain with a standard finite element method. The weakly compressible formulation of fluid flow, originally proposed in for the PFEM, is here used for the fluid domain. The PFEM has shown its capability in simulation of free surface flows in many applications. Thanks to the Lagrangian formulation, the free surface is directly defined by the current position of the particles, while the governing equations are imposed like in standard FEM. When the mesh becomes too distorted, a fast remeshing algorithm is used to redefine the connectivities. SIMULIA AbaqusExplicit has been used for the solution of the structural domain. The GC Domain Decomposition method is here used for the coupling: the problem is solved independently on each subdomain and then linked at the interface using a Lagrange multiplier technique. The proposed method allows for different time-steps in the two subdomains and for non-conforming meshes at the interfaces between the solid and fluid domains. Moreover, this approach guarantees an explicit coupling at the interfaces. 2D test-cases will be presented to validate the proposed coupling technique. The explicit scheme for both the fluid and solid subdomains, together with the explicit treatment of the coupling, makes this method appealing for applications in a variety of engineering problems with fast dynamics and/or a high degree of non-linearity

A PFEM approach to the simulation of landslide generated water-waves

A Particle Finite Element Method is here applied to the simulation of landslide-water interaction. An elastic-visco-plastic non-Newtonian, Bingham-like constitutive model has been used to describe the landslide material. Two examples are shown to show the potential of the approach

An explicit Lagrangian finite element method for free-surface weakly compressible flows

In the present work, an explicit finite element approach to the solution of the Lagrangian formulation of the Navier-Stokes equations for weakly compressible fluids or fluid-like materials is investigated. The introduction of a small amount of compressibility is shown to allow for the formulation of a fast and robust explicit solver based on a particle finite element method. Newtonian and Non-Newtonian Bingham laws are considered. A barotropic equation of state completes the model relating pressure and density fields. The approach has been validated through comparison with experimental tests and numerical simulations of free surface fluid problems involving water and waterâ\u80\u93soil mixtures

A Hu–Washizu variational approach to self-stabilized virtual elements: 2D linear elastostatics

An original, variational formulation of the Virtual Element Method (VEM) is proposed, based on a Hu–Washizu mixed variational statement for 2D linear elastostatics. The proposed variational framework appears to be ideal for the formulation of VEs, whereby compatibility is enforced in a weak sense and the strain model can be prescribed a priori, independently of the unknown displacement model. It is shown how the ensuing freedom in the definition of the strain model can be conveniently exploited for the formulation of self-stabilized and possibly locking-free low order VEs. The superior performances of the VEs formulated within this framework has been verified by application to several numerical tests

A basal slip model for Lagrangian finite element simulations of 3D landslides

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 DruckerâPrager 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 EulerianâLagrangian 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

A state of the art review of the Particle Finite Element Method (PFEM)

The particle finite element method (PFEM) is a powerful and robust numerical tool for the simulation of multi-physics problems in evolving domains. The PFEM exploits the Lagrangian framework to automatically identify and follow interfaces between different materials (e.g. fluid–fluid, fluid–solid or free surfaces). The method solves the governing equations with the standard finite element method and overcomes mesh distortion issues using a fast and efficient remeshing procedure. The flexibility and robustness of the method together with its capability for dealing with large topological variations of the computational domains, explain its success for solving a wide range of industrial and engineering problems. This paper provides an extended overview of the theory and applications of the method, giving the tools required to understand the PFEM from its basic ideas to the more advanced applications. Moreover, this work aims to confirm the flexibility and robustness of the PFEM for a broad range of engineering applications. Furthermore, presenting the advantages and disadvantages of the method, this overview can be the starting point for improvements of PFEM technology and for widening its application fields.Technology Innovation Program funded by the Ministry of Trade, Industry & Energy (MI, Korea), Grant/Award Number: 10053121; Universiti Teknologi PETRONAS (UTP) Internal Grant, Grant/Award Number: URIF 0153AAG24Peer ReviewedPostprint (published version