Parallel Algorithms for Radiation Transport on Unstructured Grids
Steven J. Plimpton, Bruce Hendrickson, Shawn P. Burns, William C. McLendon, III · 2000
The method of discrete ordinates is commonly used to solve the Boltzmann radiation transport equation for applications ranging from fire simulation to weapon effects. The equations are most efficiently solved by sweeping the radiation flux across the computational grid. For unstructured grids this poses several interesting challenges, particularly when implemented on distributed-memory parallel machines where the grid geometry is scattered across processors. We describe an asynchronous, parallel, message-passing algorithm that performs sweeps simultaneously from many directions across unstructured grids. We identify key factors that limit the algorithm's parallel scalability and discuss two enhancements we have made to the basic algorithm: one to prioritize the work within a processor's subdomain and the other to better decompose the unstructured grid across processors. Performance results are given for the basic and enhanced algorithms implemented within a radiation solver ...