Denovo: A new three-dimensional parallel discrete ordinates code in SCALE

Denovo is a new, three-dimensional, discrete ordi nates (SN) transport code that uses state-of-the-art so lution methods to obtain accurate solutions to the Boltzmann transport equation. Denovo uses the Koch Baker-Alcouffe parallel sweep algorithm to obtain high parallel efficiency on 0(100) processors on XYZ orthog onal meshes. As opposed to traditional 5 codes that use source iteration, Denovo uses nonstationary Krylov methods to solve the within-group equations. Krylov methods are far more efficient than stationary schemes. Additionally, classic acceleration schemes (djffusion syn thetic acceleration) do not suffer stability problems when used as a preconditioner to a Krylov solver. Denovo's generic programming framework allows multiple spa-tial discretization schemes and solution methodologies. Denovo currently provides diamond-difference, theta- weighted diamond-difference, linear-discontinuous fi nite element, trilinear-discontinuous finite element, and step characteristics spatial differencing schemes. Also, users have the option of running traditional source it eration instead of Krylov iteration. Multigroup upscat ter problems can be solved using Gauss-Seidel iteration with transport, two-grid acceleration. A parallel first- collision source is also available. Denovo solutions to the Kobayashi benchmarks are in excellent agreement with published results. Parallel performance shows ex cellent weak scaling up to 20000 cores and good scal ing up to 40000 cores.