Bettinotti, O.

Cremonesi, M.

Kurkchubasche, A.

Meduri, S.

Oancea, A.

Perego, U.

S. Meduri

M. Cremonesi

U. Perego

O. Bettinotti

A. Kurkchubasche

A. Oancea

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YIC 2017IV ECCOMAS YOUNG INVESTIGATOR CONFERENCE13-15 September 2017, Milano, ItalyA staggered fully explicit lagrangian Finite ElementMethod for Fluid-Structure-Interaction problemsS. Meduri∗, M. Cremonesi∗, U. Perego∗,O. Bettinotti†, A. Kurkchubasche † and V. Oancea†∗ Department of Civil and Environmental EngineeringPolitecnico di MilanoPiazza Leonardo da Vinci, 32, 20133 Milano, Italye-mail: simone.meduri@polimi.it† R&D Dassault Syste`mes SIMULIA Abaqus,1301 Atwood Avenue, Johnston, RI 02919 United StatesKEYWORDS: Particle Finiite Element Method (PFEM); Fluid Structure Interaction;Explicit Dynamics; Lagrangian Formulation.ABSTRACTThe efficient numerical simulation of Fluid Structure Interaction (FSI) problems is a topicof great relevance because of the wide range of applications in many engineering fields.Several approaches have been presented in the literature to address these problems. Apossible strategy is to include the fluid and the structure subdomains in a unified modelto be solved monolithically. Another strategy is the staggered (or partitioned) approach,where the two subdomains are solved independently and then coupled exchanging datathrough common interfaces. Moreover, different formulations depend on the kinematicdescription of the two material subdomains. In general, on the fluid side the Euleriandescription is preferred to avoid mesh distorsion, but it requires surface tracking algorithmsto identify the evolving boundaries.Here we present a staggered and fully lagrangian approach for FSI problems. The fluidsubdomain is modelled through the Particle Finite Element Method (PFEM) [1]: itslagrangian formulation is particularly suitable for the description of free surface flows andFSI problems with large structural displacements, i.e. when the fluid boundaries canvary significantly. The boundaries are automatically defined by the position of the meshnodes, with no need for interface tracking algorithms. When the mesh gets too distorted,a Delaunay Triangulation is applied to redefine element connectivities.A distinctive feature of the proposed approach is that the solid domain is modelled with theexplicit Finite Element Method (FEM) implemented in the commercial software DassaultSyste`mes SIMULIA Abaqus/Explicit. This will allow to include in the model all itsadvanced functionalities, such as the wide library of material constitutive relations andthe possibility to introduce crack propagation and contact.The explicit coupling algorithm is based on a Domain Decomposition Method, namely theGravouil and Combescure (GC) algorithm, initially proposed for structural dynamics [2],and then extended to FSI problems, for example in [3]. According to the GC algorithm,the fluid and structural domain are solved independently, as if there was no interactionbetween them. The two staggered analyses are then synchronized by considering a systemBbhRsH(a) Test case geometry (b) t = 1.50 s (c) t = 3.50 s (d) t = 10.0 sFigure 1: Filling of an elastic membrane. Geometry of the problem and snapshots of the simula-tion at different time instants [4].of constraint equations at the fluid-structure interface, which impose the continuity ofthe velocities through the definition of interface tractions. These tractions, that play therole of lagrangian multipliers, are then applied as natural boundary conditions to correctthe solutions of the two subdomains. This method allows to use different time stepsand nonconforming meshes in the different domains, which is crucial for the efficiencyof an explicit solver involving different materials. It has been demonstrated that thisalgorithm preserves stability of each sub-problem, since the numerical energy variation atthe interface is either null or strictly dissipative.The obtained fully explicit solver is appealing for its possible application in a large varietyof engineering problems with fast dynamics and/or a high degree of non-linearity. Theapproach has been validated in [4] considering several test cases presented in the literature.For instance, figure 1 shows the results of the simulation of a viscous fluid falling onto athin and highly deformable elastic membrane. The comparison of all the considered testcases with the available analytical, experimental and numerical solutions showed a goodagreement, confirming the robustness of the proposed method.REFERENCES[1] M. Cremonesi, S. Meduri, U. Perego, A. Frangi. An explicit Lagrangian finite elementmethod for free-surface weakly compressible flows. Comp. Part. Mech. 1-13, 2016.[2] G. Gravouil , A. Combescure. Multi-time-step explicit-implicit method for non-linearstructural dynamics. Int. J. Numer. Meth. in Engng. 50:199-225, 2001.[3] J. Nunez-Ramirez , J.C. Marongiu ,M. Brun , A. Combescure. A partitioned approachfor the coupling of SPH and FE methods for transient non-linear FSI problems withincompatible time-steps. Int. J. Numer. Meth. in Engng.[4] S. Meduri, M. Cremonesi, U. Perego, O. Bettinotti, A. Kurkchubasche, V. Oancea. Acoupled fully Explicit Lagrangian Finite Element and Particle Finite Element Methodfor highly nonlinear Fluid-Structure-Interaction problems. Int. J. Numer. Meth. inEngng.(SUBMITTED).

A staggered fully explicit lagrangian Finite Element Method for Fluid-Structure-Interaction problems

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A staggered fully explicit lagrangian Finite Element Method for Fluid-Structure-Interaction problems

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