PALM - A large-eddy simulation model performing on massively parallel computers

TLDR

Periodic boundary conditions in both horizontal directions reduce the effort required for parallelization. The LES model was fully recoded for distributed‑memory parallel systems, using two‑dimensional domain decomposition and MPI for communication. PALM achieves excellent performance with near‑linear speed‑up on SGI/Cray‑T3E systems, and its parallelization strategy, performance, validation experiments, and future applications are discussed.

Abstract

An existing code of a large-eddy simulation (LES) model for the study of turbulent processes in the atmospheric and oceanic boundary layer has been completely recoded for use on massively parallel systems with distributed memory. Parallelization is achieved by two-dimensional domain decomposition and communication is realized by the message passing interface (MPI). Periodic boundary conditions, which are used in both horizontal directions, helped to minimize the parallelization effort. The performance of the new PArallelized LES Model (PALM) is excellent on SGI/Cray-T3E systems and an almost linear speed-up is achieved up to very large numbers of processors. Parallelization strategy and model performance is discussed and validation experiments as well as future applications are presented.