Office of Nuclear Energy

Nek5000 Ready to Use after Simulations of Important Pipe Flow Benchmark

January 29, 2013

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Velocity magnitude in MATiS-H spacer grid with swirl-type vanes.

Velocity magnitude in MATiS-H spacer grid with swirl-type vanes.

As part of the on-going Nek5000 validation efforts, a series of large eddy simulations (LES) have been performed for thermal stratification in a pipe. Results were in good agreement with the experiment and the simulation data has provided insight into the physics of the flow. An additional series of simulations of the OECD-NEA MATiS-H benchmark has also been completed using intermediate- fidelity modeling approaches, such as k-epsilon, k-omega shear stress transport, and ID detached eddy simulation, as well as one high-fidelity approach (LES). The data has been submitted to OECD-NEA. [ANL]

Sharp supporting elements

During this quarter, the framework team was involved in two primary efforts, mesh generation and implementation of a MOAB-based coupled multi-physics simulation. For mesh generation, finishing touches were put on three major, high-complexity hexahedral meshes, and support was provided for their use in various simulations:

  • MATiS-H, an OECD-NEA experiment for single-phase flow over a rod bundle and grid. [ANL]
  • Nuscale, a hexahedral mesh of the core internals of the Multi-Application Small Light Water Reactor, a 1/3-scale mockup of the Nuscale reactor. [ANL]
  • XX09, a high-fidelity model of the XX09 test fuel assembly used in the EBR-II Shutdown Heat Removal Test experiments. [ANL]

These meshes each had 500,000-1,500,000 elements and geometric complexity that exceeds that of any other reactor simulations done recently under NEAMS. In the area of coupled multi-physics analysis, a coupled Nek5000- Proteus simulation tool was implemented, based on MOAB’s solution transfer and a new Coupé coupled multi- physics driver. The tool was used to demonstrate parallel, coupled analysis of a simple seven-pin reactor assembly, and it is currently being applied to the XX09 model described above. [ANL]

Q3, 2012