Acceleration of 2-D Finite Difference Time Domain Acoustic Wave Simulation Using GPUs

A Two-Dimensional Finite Difference Time Domain (2D-FDTD) simulation is used to find the source location of an acoustic wave in an urban area using a time-reversal technique. This method potentially allows soldiers on the battlefield to locate the source of an acoustic wave produced by gunfire or other sources. The simulation has been demonstrated to accurately find the location of the acoustic waves, but required hours to compute the solution. For practical use in the future, the simulation must run quickly to allow soldiers to find the location of their attacker before the attacker can leave the area, requiring us to accelerate the code to produce a solution in a reasonable amount of time. The simulation code requires many independent computations for each element of a large 2D grid. Graphics Processing Units (GPUs) perform best for highly-parallel and computationally-intense problems, making this an ideal simulation to compute using GPUs to significantly reduce the running time. GPUs also allow the solution to be obtained locally (with the soldiers) rather than at a centralized high performance computing center. This work develops a GPU version of the 2D-FDTD code and experiments with a variety of optimizations to produce an accurate solution as quickly as possible. GPU-only and CPU-GPU versions are developed, with the CPU-GPU version showing slightly better performance. Careful selection of thread block parameters is needed to load data from memory as quickly as possible. Over 11 times speedups are produced, providing progress towards a solution that can allow people on the battlefield to locate the source of gunfire and other projectiles in close to real-time.