Spatial domain-based parallelism in large scale, participating-media, radiative transport applications

Abstract

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Parallel algorithms for transport sweeps on unstructured meshes

“…To cope with this limitation imposed by the SDD, some authors use a block Jacobi approximation [15,3,4], in which the unknown values at the upstream boundaries of the spatial subdomains are obtained from old iterations. This method can be tuned with different prioritization strategies but, in general, suffers from degradation in the convergence rate when the number of parallel processes is increased.…”

“…In the above algorithm, the main loop (lines [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] is repeated until all owned nodes at each ordinate have been solved. Hereinafter we refer to an iteration of the main loop as a stage of the sweep algorithm.…”

“…When a node with an outgoing neighbor belonging to another subdomain is solved, its information is immediately sent to the adjacent subdomain (line 14). Finally, when one processor has no more tasks in its solvable list, messages sent from other processors are read with the aim to enable new nodes to be solved (lines [15][16][17][18][19].…”

“…In the algorithm described above, the solvable list is split by ordinates and the new lists l i p are solved one after the other (lines[6][7][8][9][10][11][12][13][14][15]. While the tasks of l i p are being solved, if new nodes become solvable for ordinate i, they are appended to l i p (line 13).…”

GPU accelerated simulations of 3D deterministic particle transport using discrete ordinates method

“…Fast and accurate simulations of physical systems whose evolutions depend on the transport of subatomic particles coupled with other complex physics are of great interest to applications ranging from simulation of fire to nuclear reactors and radiative transfer in stellar atmospheres [1,2]. For example, in the simulation of a fire, thermal energy radiates throughout the domain and interacts with boundaries such as structures and with the combustion volume itself as a participating media [3]. The design, analysis and control of nuclear reactors require solving the particle (neutron) transport equation in order to determine the particle distribution in the reactor, and hence validate and verify the specifical design and safety parameters.…”