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Submapping is a meshing tool for generating structured meshes on non-4-sided surfaces and non-6-sided volumes. An important part of submapping is the assignment of corners in the map to vertices bounding surfaces or edges bounding volumes. In models with fillet, chamfer and round features, corner assignment is difficult, since these features remove discontinuous changes in edge/surface normal, replacing them with features having smooth changes in normal direction. Also required for submapped surfaces and volumes is that corner or edge types bounding a surface or volume sum to four or six, respectively. This paper combines the use of templates to identify surface submapped corners for a variety of common feature types, and the use of an optimization approach to guarantee satisfaction of the sum = 4 − 4 g constraint for submapped surfaces (g is the number of holes). This approach not only works well in the presence of features, but can drastically reduce the user interaction required to set up and mesh models with many features. [ABSTRACT FROM AUTHOR]

Recent advances in supercomputers and parallel solver techniques have enabled users to run large simulations problems using millions of processors. Techniques for multiphysics nuclear reactor core simulations are under active development in several countries. Most of these techniques require large unstructured meshes that can be hard to generate in a standalone desktop computers because of high memory requirements, limited processing power, and other complexities. We have previously reported on a hierarchical lattice-based approach for generating reactor core meshes. Here, we describe efforts to exploit coarse-grained parallelism during reactor assembly and reactor core mesh generation processes. We highlight several reactor core examples including a very high temperature reactor, a full-core model of the Korean MONJU reactor, a ¼ pressurized water reactor core, the fast reactor Experimental Breeder Reactor-II core with a XX09 assembly, and an advanced breeder test reactor core. The times required to generate large mesh models, along with speedups obtained from running these problems in parallel, are reported. A graphical user interface to the tools described here has also been developed. [ABSTRACT FROM AUTHOR]

One of the most robust and widely used algorithms for all-hexahedral meshes is the sweeping algorithm. However, for multi- sweeping, the most difficult problems are the surface matching and interval assignment for edges on the source and target surfaces. In this paper, a new method to generate surface meshes by imprinting edge patches between the source and target surfaces is proposed. The edge patch imprinting is based on a cage-based morphing of edge patches on the different sweeping layers where deformed and undeformed cages are extracted by propagating edge patches on the linking surfaces. The imprinting results in that the source or target surfaces will be partitioned with the imprinted edge patches. After partitioning, every new source surface should be matched to a new specific target surface where surface mesh projection from one-to-one sweeping based on harmonic mapping[19] can be applied. In addition, 3D edge patches are projected onto 2D computational domains where every sweeping level is planar in order to increase the robustness of imprinting. Finally, the algorithm time complexity is discussed and examples are provided to verify the robustness of our proposed algorithm. [ABSTRACT FROM AUTHOR]

Abstract: We report on a demonstration of loose multiphysics coupling between a basin modeling code and a seismic code running on a large parallel machine. Multiphysics coupling, which is one critical capability for a high performance computing (HPC) framework, was implemented using the MOAB open-source mesh and field database. MOAB provides for code coupling by storing mesh data and input and output field data for the coupled analysis codes and interpolating the field values between different meshes used by the coupled codes. We found it straightforward to use MOAB to couple the PBSM basin modeling code and the FWI3D seismic code on an IBM Blue Gene/P system. We describe how the coupling was implemented and present benchmarking results for up to 8 racks of Blue Gene/P with 8192 nodes and MPI processes. The coupling code is fast compared to the analysis codes and it scales well up to at least 8192 nodes, indicating that a mesh and field database is an efficient way to implement loose multiphysics coupling for large parallel machines. [Copyright &y& Elsevier]