Parallel implementations of the fast nearfield method for continuous-wave and transient pressure calculations

Abstract

FOCUS, the “Fast Object-oriented C + + Simulator” (https://www.egr.msu.edu/∼fultras-web/), enables rapid calculations of continuous-wave and transient pressure fields generated by single transducers and phased arrays. FOCUS achieves small errors in relatively short computation times through memory-efficient calculations with the fast nearfield method, which converges exponentially. The fast nearfield method is also an embarrassingly parallel algorithm that supports further reductions in the computation time through hardware acceleration. Previous efforts to accelerate calculations with the fast nearfield method successfully implemented multithreading within multiple central processing unit (CPU) cores using OpenMP, and this capability is presently included with FOCUS. Prior success with OpenMP motivates ongoing efforts to further extend the functionality of FOCUS by interfacing the fast nearfield method to an NVIDIA graphics processing unit (GPU). To facilitate FOCUS calculations on a GPU, calculations with the fast nearfield method are implemented in CUDA for time-harmonic and transient pressure computations with each supported transducer shape. This combination achieves a significant reduction in the computation time compared to single-threaded execution. When evaluated on an NVIDIA 1670 GPU, the computation time is also approximately halved relative to the multithreaded OpenMP implementation. These results encourage further efforts to parallelize existing and future FOCUS routines.