  COSA is a novel CFD system based on the compressible Navier-Stokes model for
unsteady aerodynamics and aeroelasticity of fixed structures, rotary wings and
turbomachinery blades. It includes a steady, time domain, and harmonic balance
flow solver.
  COSA has primarily been parallelised using MPI, but there is also a hybrid
parallelisation that adds OpenMP functionality to the MPI parallelisation to
enable larger number of cores to be utilised for a given simulation as the MPI
parallelisation is limited to the number of geometric partitions (or blocks) in
the simulation, or to exploit multi-threaded hardware where appropriate. This
paper outlines the work undertaken to optimise these two parallelisation
strategies, improving the efficiency of both and therefore reducing the
computational time required to compute simulations. We also analyse the power
consumption of the code on a range of leading HPC systems to further understand
the performance of the code.
