Negative Flux Fixups in Discontinuous Finite Element SN Transport
نویسندگان
چکیده
We introduce a conservative fixup strategy to remedy negative fluxes within a linear discontinuous spatially discretized radiation transport solver. The strategy is similar in principle to the classical setto-zero fixup used with diamond difference schemes. We also discuss difficulties in creating an effective solver for such an approach and propose a hybrid source iteration/Krylov solver. Numerical results are presented for 2-D test cases.
منابع مشابه
A Non-linear Optimal Discontinuous Petrov-galerkin Method for Stabilising the Solution of the Transport Equation
This paper describes a new Non-Linear Discontinuous Petrov-Galerkin (NDPG) method and application to the one-speed Boltzmann Transport Equation (BTE) for space-time problems. The purpose of the method is to remove unwanted oscillations in the transport solution which occur in the vicinity of sharp flux gradients, while improving computational efficiency and numerical accuracy. This is achieved ...
متن کاملComparison of Linear and Quadratic Discontinuous Spatial Finite Element Methods for Parallel Sn Transport on Triangles
We compare the performance of linear and quadratic discontinuous finite elements methods spatial discretizations (LDFEM and QDFEM) of the SN transport equation on triangles in twodimensional, axisymmetric coordinate system (r-z). Numerical results reveal that both unlumped and fully lumped LDFEM are second order accurate as expected. The QDFEM exhibits third order accuracy. Because the QDFEM is...
متن کاملDiscontinuous Finite Element Sn Methods on 3-D Unstructured Grids
Discontinuous finite element methods for the SN equations on 3-D unstructured tetrahedral and hexahedral meshes are presented. Solution techniques including source iteration and diffusion-synthetic acceleration are described. Numerical results are presented which demonstrate the accuracy and efficiency of these methods.
متن کاملNonlinear Diffusion Acceleration for the Multigroup Transport Equation Discretized with SN and Continuous FEM with Rattlesnake
Nonlinear diffusion acceleration (NDA) can improve the performance of a neutron transport solver significantly especially for the multigroup eigenvalue problems. The high-order transport equation and the transport-corrected low-order diffusion equation form a nonlinear system in NDA, which can be solved via a Picard iteration. The consistency of the correction of the low-order equation is impor...
متن کاملA spherical harmonics—Finite element discretization of the self-adjoint angular flux neutron transport equation
The spherical harmonics (PN) method is widely used in solving the neutron transport equation, but it has some disadvantages. One of them omes from the complexity of the PN equations. Another one comes from the difficulty of dealing with the vacuum boundary condition exactly. In his paper, the PN method is applied to the self-adjoint angular flux (SAAF) neutron transport equation and a set of PN...
متن کامل