Author: Dennis J. Miller (CAPT, USAF.)Publisher:
ISBN:
Category : Neutron transport theory
Languages : en
Pages : 242
Book Description
Linear Characteristic Spatial Quadrature for Discrete Ordinates Neutral Particle Transport on Arbitrary Triangles
Author: Dennis J. Miller (CAPT, USAF.)Publisher:
ISBN:
Category : Neutron transport theory
Languages : en
Pages : 242
Book Description
Linear Characteristic Spatial Quadrature for Discrete Ordinates Neutral Particle Transport on Arbitrary Triangles
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 135
Book Description
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 produce less than 1.0 percent variation in results. Test cases included a rectangular region with diagonal vacuum duct, and cylindrical source region with rotated rings of annular segmented reflectors. The triangle linear characteristic quadrature is more cost effective on these problems achieving a relative error of less than 1.0 percent with a factor of three to over a hundred fewer spatial cells, with less than three times the computational cost per cell. This spatial cell savings should increase the practical problem domain for which discrete ordinates is usable ... Neutron transport, Photon transport, Boltzmann equation, Numerical methods.
Characteristic Spatial Quadratures for Discrete Ordinates Neutral Particle Transport on Arbitrary Tetrahedral Meshes
Author: Charles R. BrennanPublisher:
ISBN: 9781423578253
Category : Numerical grid generation (Numerical analysis)
Languages : en
Pages : 228
Book Description
Characteristic spatial quadratures for discrete ordinates calculations on meshes of arbitrary tetrahedra are derived and tested, including the step (SC), linear (LC), and exponential (EC) characteristic quadratures and variants that assume constant distributions on cell faces. Tetrahedral meshes accurately model curved surfaces with few cells. A split cell approach subdivides tetrahedra along the streaming direction, reducing the transport to one dimension. Assumed forms of the cell source and entering flux distributions have sufficient parameters to match the zeroth and first spatial moments. These parameters are determined by analytically inverting a linear system (LC), or by numerical inversion using Newton's method (EC). Efficient algorithms for the two and three dimensional rootsolves are derived. The constant face methods proved unacceptable in empirical testing. Both LC and EC exhibited third order convergence. LC provided accurate results on cells with optical thickness on the order of one mean free path while EC was accurate with fewer, thicker cells. LC can produce negative fluxes; EC is strictly positive. Although more costly per cell, EC is robust and can be more efficient than LC or SC by using coarse meshes.
Scientific and Technical Aerospace Reports
Author: Mathematics and Computations, Reactor Physics, and Environmental Analyses
Author: Nuclear Science and Engineering
Author: A Linear Characteristic-nodal Transport Method for the Two-dimensional (x, Y)-geometry Multigroup Discrete Ordinates Equations Over an Arbitrary Triangle Mesh
Author: Richard R. PaternosterPublisher:
ISBN:
Category : Boundary value problems
Languages : en
Pages : 256
Book Description
American Doctoral Dissertations
Author: Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 796
Book Description
Government Reports Annual Index
Author: Publisher:
ISBN:
Category : Government reports announcements & index
Languages : en
Pages : 1450
Book Description
Government Reports Announcements & Index
Author: Publisher:
ISBN:
Category : Government publications
Languages : en
Pages : 1330
Book Description