Partitioned solver for strongly coupled fluid–structure interaction
Résumé
In this work a fluid–structure interaction solver is developed in a partitioned approach using blockGauss–Seidel implicit scheme. Finite volume method is used to discretize the fluid flow problem on amoving mesh in an arbitrary Lagrangian–Eulerian formulation and by using an adaptive time step. Thepressure–velocity coupling is performed by using the PIMPLE algorithm, a combination of both SIMPLEand PISO algorithms, which permits the use of larger time steps in a moving mesh. The structural elasticdeformation is analyzed in a Lagrangian formulation using the St. Venant–Kirchhoff constitutive law, fornon-linear large deformations. The solid structure is discretized by the finite volume method in an iterativesegregated approach. The automatic mesh motion solver is based on Laplace smoothing equationwith variable mesh diffusion. The strong coupling between the different solvers and the equilibriumon the fluid–structure interface are achieved by using an iterative implicit fixed-point algorithm withdynamic Aitken’s relaxation method. The solver, which is called vorflexFoam, is developed using the opensource C++ library OpenFOAM. The solver is validated on two different benchmarks largely used in theopen literature. In the first one the structural deformation is induced by incompressibility. The secondbenchmark consists on a vortex excited elastic flap in a Von Karman vortex street. Finally, a more complexcase is studied including two elastic flaps immersed in a pulsatile flow. The present solver detectsaccurately the interaction between the complex flow structures generated by the flaps and the effectof the flaps oscillations between each other.