Real-world computer simulation by using a GPU-rich supercomputer

Real-world simulations based on fluid dynamics require huge amount of computer resources. Only by large-scale computation on world top-class supercomputers the computational demands can be satisfied. We demonstrate three applications carried out on the whole TSUBAME 2.0 system, which has 2.4 PFLOPS of the peak performance with more than 4,000 GPUs (Graphics Processing Unit) at the Tokyo Institute of Technology. The upgrade of TSUBAME is on-going and the performance will be improved to 5.7 PFLOPS (double precision) and 17 PFLOPS (single precision). Since there are more than 2,000 small processing cores in a single GPU chip, it is necessary to make programs based on data-parallel algorithm to extract high performance from the GPU. First, we show high resolution meso-scale atmosphere model ASUCA that is being developed by the Japan Meteorological Agency (JMA) for the purpose of the next-generation weather forecasting service. We have succeeded in a weather prediction with 500-m resolution (cf. Current JMA weather forecast uses 5km mesh). We also show an air flow simulation for 10 km × 10 km area of a central part of metropolitan Tokyo with 1-m resolution by Lattice Boltzmann method, in which a new Large-Eddy Simulation model has been employed. Finally we talk about a phase-field simulation to develop new materials by studying the dendritic solidification of Al-Si alloy. We achieved 2.0 PFLOPS in single precision, which is 44.5% of the peak performance. The GPU-based TSUBAME has high electrical power efficiency and we have obtained simulation results with less energy.