Développement d'algorithmes parallèles pour la simulation d'écoulements de fluides dans les milieux poreux

Two different parallel lattice Boltzmann (LBM) algorithms have been devised for the simulation of flow through complex porous media. They are based on memory efficient LBM algorithms, namely the one-lattice and shift algorithms, combined with vector data structure, even fluid node vector partitioning domain decomposition and efficient data transfer layouts. The shift implementation also includes a single unit relaxation scheme that allows additional memory savings, but limits its validity to Newtonian fluids. They both provide high parallel performance by balancing the workload among the processors and reducing the amount of data that need to be transferred, and reduce significantly the memory usage as compared to previous parallel LBM codes presented in the literature. Theoretical parallel performance and memory usage models developed show that they also offer a good evolutivity and efficiencies as high as 79% for simulations made of several billions of fluid nodes on 128 processors are reported. The application of one of these algorithms for the simulation of flow through compressed packings made of highly polydisperse spheres has demonstrated the remarkable precision and efficiency of the algorithm proposed. As a result, a modified Carman-Kozeny correlation taking into account the compression level and the particle polydispersity has been formulated.