Conference Proceedings Paper
On the Development of Parallel Linear Solvers for Simulations of Reactor Thermalhydraulics
NURETH-14 - 2011 September 25-30
Yan Yan (Columbia University)
Steven Antal (RPI)
Brian Edge (RPI)
David Keyes (Columbia University)
Dillon Shaver (RPI)
Igor Bolotnov (RPI)
Michael Podowski (RPI)
The state-of-the-art multiphase fluid dynamics code, NPHASE-CMFD, performs
multiphase flow simulations in complex domains using implicit nonlinear treatment of the
governing equations and in parallel, which is a very challenging environment for the linear
solver. The present work illustrates how the Portable, Extensible Toolkit for Scientific
Computation (PETSc) and scalable Algebraic Multigrid (AMG) preconditioner from Hypre
can be utilized to construct robust and scalable linear solvers for the Newton correction
equation obtained from the discretized system of governing conservation equations in
NPHASE-CMFD. The overall long-tem objective of this work is to extend the
NPHASE-CMFD code into a fully-scalable solver of multiphase flow and heat transfer
problems, applicable to both steady-state and stiff time-dependent phenomena in complete
fuel assemblies of nuclear reactors and, eventually, the entire reactor core (such as the
Virtual Reactor concept envisioned by CASL). This campaign appropriately begins with the
linear algebraic equation solver, which is traditionally a bottleneck to scalability in
PDE-based codes. The computational complexity of the solver is usually superlinear in
problem size, whereas the rest of the code, the “physics” portion, usually has its complexity
linear in the problem size.
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