Issue 29

A. De Rosis et alii, Frattura ed Integrità Strutturale, 29 (2014) 343-350; DOI: 10.3221/IGF-ESIS.29.30 343 Focussed on: Computational Mechanics and Mechanics of Materials in Italy A numerical framework for simulating fluid-structure interaction phenomena A. De Rosis Department of Agricultural Sciences, University of Bologna, Viale Giuseppe Fanin 48, 40127 Bologna alessandro.derosis@unibo.it S. de Miranda, C. Burrafato, F. Ubertini Department of Civil, Environmental, Chemical and Materials Engineering, University of Bologna stefano.demiranda@unibo.it, carlo.burrafato2@unibo.it , francesco.ubertini@unibo.it A BSTRACT . In this paper, a numerical tool able to solve fluid-structure interaction problems is proposed. The lattice Boltzmann method is used to compute fluid dynamics, while the corotational finite element formulation together with the Time Discontinuous Galerkin method are adopted to predict structure dynamics. The Immersed Boundary method is used to account for the presence of an immersed solid in the lattice fluid background and to handle fluid-structure interface conditions, while a Volume-of-Fluid-based method is adopted to take trace of the evolution of the free surface. These ingredients are combined through a partitioned staggered explicit strategy, according to an efficient and accurate algorithm recently developed by the authors. The effectiveness of the proposed methodology is tested against two different cases. The former investigates the dam break phenomenon, involving the modeling of the free surface. The latter involves the vibration regime experienced by two highly deformable flapping flags obstructing a flow. A wide numerical campaign is carried out by computing the error in terms of interface energy artificially introduced at the fluid-solid interface. Moreover, the structure behavior is dissected by simulating scenarios characterized by different values of the Reynolds number. Present findings are compared to literature results, showing a very close agreement. K EYWORDS . Fluid-structure interaction; Lattice Boltzmann method; Immersed boundary method; Volume-of- Fluid method; Dam break; Flapping flags. I NTRODUCTION omputational fluid dynamics (CFD) represents a set of scientific methods whose aim is to solve problems, which involve fluids by adopting computers, algorithms and numerical methods. CFD can be studied and analyzed at three different levels. The “top” one is the so-called macroscopic level, consisting of the solution of the Navier- Stokes equations, which govern flow behavior. The “bottom” one reduces a fluid flow problem to a microscopic one and it is solved by adopting laws arising from molecular dynamics. Between these approaches, in the last decades the lattice Boltzmann (LB) method [1,2] developed as a powerful alternative to standard approaches. It is characterized by a C