AN ALE FRAMEWORK FOR MOVING BOUNDARY PROBLEMS

Per, 23/02/2017 - 14:55 — ecem.yazar
27/02/2017 15:00
Turkey
Many fluid dynamics problems involve moving/deforming boundaries that represent an interface between different fluids or between fluids and solids. Examples include a wide variety of fluid-structure interaction (FSI) problems, a large class of free-surface problems, fluid-particle interactions, swimming/flying animals, etc. The current work presents a novel numerical algorithm based on the Arbitrary Lagrangian-Eulerian (ALE) formulation, which combines the advantages of both Lagrangian and Eulerian methods, for a fully coupled solution of the large-scale fluid-structure interaction (FSI) problems. The governing incompressible Navier-Stokes equations for the fluid domain are discretized using a stable side-centered arrangement of the primitive variables that does not require any ad-hoc modifications in order to enhance pressure coupling. The continuity equation is satisfied within each element at machine precision and a special attention is also given to satisfy the Geometric Conservation Law (GCL) at discrete level. The deformation of the solid domain is governed by the constitutive laws for the nonlinear Saint Venant-Kirchhoff material and the classical Galerkin finite element method is used to discretize the governing equations in a Lagrangian frame. The resulting large-scale algebraic nonlinear equations are multiplied with an upper triangular right preconditioner which results in a scaled discrete Laplacian instead of a zero block in the original system. The parallel implementation of the present fully coupled unstructured fluid-structure solver is based on the PETSc library and a one-level restricted additive Schwarz preconditioner with a block-incomplete factorization within each partitioned sub-domains is utilized for the resulting fully coupled system. The proposed ALE approach is initially used to investigate the near wake patterns for the flapping wing flight of the fruit fly Drosophila. Then the numerical algorithm is applied to a complicated FSI problem involving unsteady pulsatile blood flow in a cerebral artery with aneurysm as a realistic fluid-structure interaction problem encountered in biomechanics.

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27.02.2017, 15:00, KUZEY KAMPÜS KARE BLOK KİMYA MÜH. BÖL. 4.KAT KB 428