Dresden 2011 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 40: Posters II

DY 40.24: Poster

Donnerstag, 17. März 2011, 17:00–19:00, P3

Parallelization of 2D Contact Dynamics in the simulation of granular media — •Zahra Shojaaee, Mohammad Reza Shaebani, Lothar Brendel, János Török, and Dietrich Wolf — University of Duisburg-Essen, Duisburg, Germany

Contact Dynamics (CD) is an effective discrete element method to simulate systems consisting of a large number of particles with multiple contacts such as granular matter. We simulate non cohesive hard discs with coulomb friction. CD uses an iterative method to calculate the contact forces, which fulfill the convergence criteria. To preserve reasonable computational time specially for large dense systems we have parallelized our CD code using open MPI. In contrast to the parallel MD method a large amount of communication between the processors is needed to calculate the contact forces in CD method. That is an important reason to pay more attention to the domain decomposition method. We have used a topological hierarchical domain decomposition method and an adaptive load balancing scheme, which aim to minimize the standard deviation of the real CPU time of all processors. The main challenge is to handle the iterative force calculation process in an optimal way. We investigate the performance of the iterative force calculation scheme, as well as the overall performance of the parallel code. Optimizing the communications between the processors results in a code which fulfills a good linear scaling also for a large number of processors. The solution remains stable until a critical number of processors depending on the system size, which deals with the weak point of CD method not bearing a parallel updating of contact forces.