Parallel Processing Enhancement to SWMM/EXTRAN
Modifications have been made to the FORTRAN source code of the EXTRAN block of SWMM, which enable the model to take advantage of parallel processors for faster program execution during runtime. These modifications have been made to the program code which performs the explicit (Modified Euler) solution of the St. Venant equations for computation of flow and head within the modeled drainage network. The code changes are designed to support use of OpenMP parallel processing directives when the code is compiled using specialized parallel processing compiler. Code changes were verified for correct parallelization and model output confirmed by testing against output produced with the serial (unmodified) version of the same source code.
Model output and runtimes were characterized for two relatively large model networks (386 and 772 conduits) by executing the serial and parallelized code on the same hardware (Windows NT workstation running dual Pentium 200 MHz microprocessors). Runtime reductions on the order of 30-37% were found for the parallelized code on this commonly available dual processor system. The modified code and OpenMP support an unlimited number of parallel processors, and greater runtime reductions are expected for more highly parallel systems (e.g. Those with four or more processors).
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