ADAPTIVE REFINEMENT OF UNSTRUCTURED FINITE ELEMENT MESHES FOR COMPRESSIBLE FLOWS

GUSTAVO A. RÍOS RODRIGUEZ; MARIO A. STORTI; NORBERTO M. NIGRO

Tandil, provincia de Buenos Aires.

Congreso; ENIEF 2009 - XVIII Congreso sobre Métodos Numéricos y sus Aplicaciones.; 2009

Instituto PLADEMA, Asociación Argentina de Mecánica Computacional AMCA

It is well known that sudden changes in the solution produced by shock waves and contact discontinuities often appear in compressible flow problems. These features of the flow field require very small size finite elements to achieve an accurate solution. However, homogeneous refinement of the whole mesh quickly becomes prohibitive for three dimensional meshes due to computational cost issues. In these situations, the use of adaptive mesh refinement strategies show advantageous. An h-adaptiveunstructured mesh refinement strategy to solve both steady and unsteady compressible flow problems by the finite element method is used in this work. The adaption algorithm is briefly introduced. Non-conformity and controlled quality are some features of the adapted meshes. Refinement constraints are enforced to guarantee a smooth size distribution amongst neighbour elements and a posteriori error indicators based on the gradient of the flow variables are used to track discontinuities through the flow field. The algorithm is implemented in the C++ programming language together with the STL and Boost libraries. The mesh adaption code is coupled to an SUPG-FEM flow solver which is run in parallel on acluster of workstations. The spherical blast wave problem known as the Taylor-Sedov problem is solved with this code and the flowfield is compared to that provided by the theory.