Towards Petascale Computing with Parallel CFD codes

Abstract

Many world leading high-end computing (HEC) facilities are now offering over 100 Teraflops/s of performance and several initiatives have begun to look forward to Petascale computing⁵ (10¹5 flop/s). Los Alamos National Laboratory and Oak Ridge National Laboratory (ORNL) already have Petascale systems, which are leading the current (Nov 2008) TOP500 list [1]. Computing at the Petascale raises a number of significant challenges for parallel computational fluid dynamics codes. Most significantly, further improvements to the performance of individual processors will be limited and therefore Petascale systems are likely to contain 100,000+ processors. Thus a critical aspect for utilising high Terascale and Petascale resources is the scalability of the underlying numerical methods, both with execution time with the number of processors and scaling of time with problem size. In this paper we analyse the performance of several CFD codes for a range of datasets on some of the latest high performance computing architectures. This includes Direct Numerical Simulations (DNS) via the SBLI [2] and SENGA2 [3] codes, and Large Eddy Simulations (LES) using both STREAMS LES [4] and the general purpose open source CFD code Code Saturne [5].