A novel ghost-cell immersed boundary method for flow in complex geometry

João Rodrigo Andrade¹; Aristeu da Silveira Neto¹; João Marcelo Vedovoto¹

¹ Universidade Federal de Uberlândia

doi:10.20906/CPS/COB-2015-1626

Resumo

In the actual application of Computational Fluid Dynamics (CFD) a conforming grid is usually used to compute the flow around an arbitrarily moving or stationary body, especially for moving geometries that require a new mesh each time step, decreasing the efficiency of computing resources. In order to bypass this numerical problem, an innovative approach called Immersed Boundary Method (IBM) was developed to impose the boundary conditions of the solid body without the need of a grid reconstruction and requiring less computational efforts. In other words, an immersed boundary method is a methodology for dealing with a body which does not necessarily have to fit conform a Cartesian grid. The IBM requires two different meshes, a Eulerian Domain which is a grid that correspond to the flow field with no regard to the surface grid and a Lagrangian mesh that represents the solid body. The critical point of this approach consists on the interpolation function or numerical manipulation to link both meshes, modifying the equations in the vicinity of the boundary and exchanging information between then. Several different branches were developed based on the IBM, these treatments can be globally categorized into continuous forcing approach, discrete forcing approach, cut-cell methods, jump-singularities methods and approximated domain methods. This work presents a ghost-cell immersed boundary method for simulation flows in complex geometries, which enforces the boundary condition through a ghost cell method and interpolation functions. Dirichlet boundary conditions can be treated. The accuracy of the current method is validated using flows pas a circular cylinder and a sphere.

Palavras-chave: imersed boundary method; ghost-cell; cartesian grid method