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Distribution Iteration: A Robust Alternative To Source Iteration For Solving The Discrete Ordinates Radiation Transport Equations In Slab And Xy- Geometries, Nicholas J. Prins
Distribution Iteration: A Robust Alternative To Source Iteration For Solving The Discrete Ordinates Radiation Transport Equations In Slab And Xy- Geometries, Nicholas J. Prins
Theses and Dissertations
The discrete ordinates method is widely used to solve the Boltzmann transport equation for neutral particle transport for many engineering applications. Source iteration is used to solve the discrete ordinates system of equations, but can be slow to converge in highly scattering problems. Synthetic acceleration techniques have been developed to address this shortcoming; however, recent research has shown synthetic acceleration to lose effectiveness or diverge for certain problems. LTC Wager introduced an alternative to source iteration and demonstrated it in slab geometry. Here the method is further developed, enhancing efficiency in various ways, and demonstrated in XY-geometry as well as …
Manufacture And Testing Of An Activation Foil Package For Use In Afids, Warren E. Kimmel
Manufacture And Testing Of An Activation Foil Package For Use In Afids, Warren E. Kimmel
Theses and Dissertations
This study used simulation and experiment to design and test foil packets for use in the Activation Foil Integrated Detection System (AFIDS). The initial plan to activate foil packets outside with the pulse reactor at White Sands Missile Range (WSMR) was not possible due to WSMR not having safety approval to take the reactor outside. As an alternative, the concept of using liquid nitrous oxide inside a reactor to simulate large volumes of air was investigated. Simulation using the Standardized Computer Analyses for Licensing Evaluation (SCALE) program was used to select ten foils to be included in the foil packet. …
Development Of A Discrete Ordinates Code System For Unstructured Meshes Of Tetrahedral Cells, With Serial And Parallel Implementations, Rodney L. Miller
Development Of A Discrete Ordinates Code System For Unstructured Meshes Of Tetrahedral Cells, With Serial And Parallel Implementations, Rodney L. Miller
Theses and Dissertations
A numerically stable, accurate, and robust form of the exponential characteristic (EC) method, used to solve the time-independent linearized Boltzmann Transport Equation, is derived using direct affine coordinate transformations on unstructured meshes of tetrahedra. This quadrature, as well as the linear characteristic (LC) spatial quadrature, is implemented in our transport code, called TETRAN. This code solves multi-group neutral particle transport problems with anisotropic scattering and was parallelized using High Performance Fortran and angular domain decomposition. A new, parallel algorithm for updating the scattering source is introduced. The EC source and inflow flux coefficients are efficiently evaluated using Broyden's rootsolver, started …
Linear Characteristic Spatial Quadrature For Discrete Ordinates Neutral Particle Transport On Arbitrary Triangles, Dennis J. Miller
Linear Characteristic Spatial Quadrature For Discrete Ordinates Neutral Particle Transport On Arbitrary Triangles, Dennis J. Miller
Theses and Dissertations
A new discrete ordinates spatial quadrature for arbitrary triangular cells is derived and compared to its rectangular cell linear characteristic counterpart. The triangular mesh is more flexible, allowing curved surfaces and off-axis angles to be approximated with many fewer spatial cells. The triangle method is consistently more accurate on example problems tested here. Arbitrary orientation and size of the triangles allow non-patterned meshes to be developed which appears to ameliorate numerical diffusion. The triangle linear characteristic quadrature converges at nearly the same rate as rectangular Linear characteristic on Lathrop's problem. Mesh sensitivity measurements show large variations in triangle vertex locations …