Alya is a multi-physics simulation code developed at Barcelona Supercomputing Center (BSC). From its inception Alya code is designed using advanced High Performance Computing programming techniques to solve coupled problems on supercomputers efficiently. The target domain is engineering, with all its particular features: complex geometries and unstructured meshes, coupled multi-physics with exotic coupling schemes and physical models, ill-posed problems, flexibility needs for rapidly including new models, etc. Since its beginnings in 2004, Alya has scaled well in an increasing number of processors when solving single-physics problems such as fluid mechanics, solid mechanics, acoustics, etc. Over time, we have made a concerted effort to maintain and even improve scalability for multi-physics problems. This poses challenges on multiple fronts, including: numerical models, parallel implementation, physical coupling models, algorithms and solution schemes, meshing process, etc. In this paper, we introduce Alya's main features and focus particularly on its solvers. We present Alya's performance up to 100.000 processors in Blue Waters, the NCSA supercomputer with selected multi-physics tests that are representative of the engineering world. The tests are incompressible flow in a human respiratory system, low Mach combustion problem in a kiln furnace, and coupled electro-mechanical contraction of the heart. We show scalability plots for all cases and discuss all aspects of such simulations, including solver convergence.

The authors would like to thank the following fellow researchers and institutions: • The Private Sector Program at NCSA and the BlueWaters sustained-petascale computing project-supported by the National Science Foundation (award number OCI 07-25070) and the state of Illinois. • Denis Doorly and Alister Bates (Imperial College London, UK), collaborators of the airways study. Part of this work was financed by European PRACE Type B/C projects. • The heart geometry was provided by Dr. A. Berruezo (Hospital Clinic de Barcelona) in collaboration with R. Sebastian (UVEG) and O. Camara (UPF), partially financed through project TIN2011-28067 from MINECO, Spain. • Part of the cardiac model development was financed by the grant SEV-2011-00067 of Severo Ochoa Program, awarded by the Spanish Government. • Part of the kiln model development was financed by the European Commission in the framework of the FP7 Collaborative project “Advanced Technologies for the Production of Cement and Clean Aggregates from Construction and Demolition Waste (C2CA)”, Grant Agreement No 265189.

Peer Reviewed