A parallel domain decomposition algorithm for coastal ocean circulation models based on integer linear programming
This paper presents a new parallel domain decomposition algorithm based on integer linear programming (ILP), a mathematical optimization method. To minimize the computation time of coastal ocean circulation models, the ILP decomposition algorithm divides the global domain in local domains with balanced work load according to the number of processors and avoids computations over as many as land grid cells as possible. In addition, it maintains the use of logically rectangular local domains and achieves the exact same results as traditional domain decomposition algorithms (such as Cartesian decomposition). However, the ILP decomposition algorithm may not converge to an exact solution for relatively large domains. To overcome this problem, we developed two ILP decomposition formulations. The first one (complete formulation) has no additional restriction, although it is impractical for large global domains. The second one (feasible) imposes local domains with the same dimensions and looks for the feasibility of such decomposition, which allows much larger global domains. Parallel performance of both ILP formulations is compared to a base Cartesian decomposition by simulating two cases with the newly created parallel version of the Stevens Institute of Technology’s Estuarine and Coastal Ocean Model (sECOM). Simulations with the ILP formulations run always faster than the ones with the base decomposition, and the complete formulation is better than the feasible one when it is applicable. In addition, parallel efficiency with the ILP decomposition may be greater than one.
KeywordsCoastal ocean circulation model Parallel computing Domain decomposition Integer linear programming Urban ocean ECOM
This work was partially funded by a research task agreement entered between the Trustees of the Stevens Institute of Technology and the Port Authority of New York and New Jersey, effective August 19, 2014. The authors would like to acknowledge the unwavering support of Mr. David Dodd, Vice President for Information Technology and CIO at Stevens Institute of Technology. We would also like to thank Karen Swift, Kevin Ying, Joe Formoso, David Runnels, Kurt Hockenbury, and James Cunningham, for their assistance with the Pharos Hyperscale Supercomputing Facility.
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