An Immersed Boundary - Lattice Boltzmann method for incompressible flows through moving porous media

Abstarct: A numerical framework based on the Immersed Boundary and the Lattice Boltzmann method is proposed to simulate the fluid flow through moving porous media. It is based on the formulation of Guo and Zhao which includes the porosity in the classical B.G.K. implementation, augmented by the Darcy-Forchheimer force terms. Various methods of implementing a porous medium of complex geometry are tested, based on the Immersed Boundary method. The boundaries can be either curved, i.e. non conformal to the Cartesian lattice, or moving/deformable over the fixed lattice. The basic idea consists of imposing the porous boundary conditions through a system of singular forces, de fining the boundary of the medium. The communication between fluid and porous media are ensured by interpolation and spreading using molli fiers. Several academical configurations are examined (square and circular cylinder), to validate the numerical implementations on literature studies. A special care is dedicated to comparing the flow topology, both inside the cylinder, and in the wake of the cylinder (recirculation bubble). Both stationary and moving media will be considered, focussing on the numerical issues raised by tackling such complex con figurations. One application of the present work concerns the  flow control around bluff bodies using moving porous media. Within this context, the drag-reducing properties of such passive actuator will be studied, as well as the e ffect of shape-adaptation/reconfiguration on the wake.

Date et lieu: le Jeudi 4 Juin à 11h00 au M2P2  (Château Gombert IMT La Jetée, Amphi 2ème étage)