3.1. Introduction to Angular Quadratures

Discrete-ordinates codes need angular quadratures to select the sweeping directions and to compute moments of the angular flux.

Several choices are available:

  • A Product Quadrature set (using Gauss-Legendre quadrature along the polar angle, and a Gauss-Chebyshev quadrature along the azimuthal angle)

  • A Triangular Quadrature set (using Gauss-Legendre quadrature along the polar angle, with decreasing orders of Gauss-Chebyshev quadrature along the azimuthal angle)

  • A Linear Discontinuous Finite Element (LDFE) Quadrature set that allows for local angular refinement

  • A Lebedev Quadrature set

Additionally, there are various options for how the discrete-to-moment flux map is constructed.

  • The Standard construction method

  • Galerkin-Quadrature Method 1

  • Galerkin-Quadrature Method 3