Parallel computation of the phonon Boltzmann transport equation

In this paper, the performance of a parallel implementation of the phonon Boltzmann Transport Equation (BTE) is tested. Two three-phonon scattering models, the full scattering model and the anisotropic relaxation time model, are considered. The finite volume method is used to solve the Boltzmann Transport Equation (BTE) numerically. Two strategies are explored: spatial domain decomposition and phonon band decomposition. The parallel computations are first validated by comparing parallel simulation results with those obtained from serial simulations. Computation and communication times for different cases are investigated. Overall parallel performance, as measured by speedup, is studied for the two BTE models using the two decomposition strategies on a Linux cluster. The spatial domain decomposition strategy is seen to work best with the full-scattering BTE model, which scales well up to 128 processors even for modest spatial grids because of the large computational load due to the scattering calculation. For the anisotropic relaxation BTE model, good scaling of parallel computation was achieved by up to 20 processors because of the relatively small per-processor computational load.