Métodos de fronteira imersa para corpos esbeltos: implementação e validação

Abstract

The immersed boundary (IB) methods are used to enforce boundary conditions on surfaces not aligned with the computational mesh in a numerical simulation. This methodology has been used as a practical approach to model flow problems involving complex and/or moving bodies. Despite the great advantages of the immersed boundary methodology, it is shown in this work that some difficulties and challenges are posed when it is used to simulate the flow past sharp geometries. In present work, two main objectives are proposed: first, to assess the accuracy and efficiency of IB methods in simulations of flows past immersed bodies with highly sharp corners or thin plates. Secondly, we implement a numerical method which is able to satisfy these flow conditions. The study was composed of four stages: First, an extensive bibliographic review was conducted in order to know and understand the different immersed boundary methods; in the second stage it was presented modifications in Multi-Direct Forcing method; further on, it was presented a local directional ghost cell approach. Finally, the methods are implemented and tested for a number of problems, the modified multi-direct forcing approach was validated for a uniform flow past a circular cylinder, a sphere and an airfoil NACA0012. The local directional ghost cell approach was employed to calculate a Poiseuille flow, an impulsively started flow past a flat plate and uniform flow around a circular cylinder between two parallels walls