EXTENSION TO COMPLEX GEOMETRIES OF THE HYBRID FINITE ELEMENT/FINITE VOLUME METHOD FOR THE SOLUTION OF THE RADIATIVE TRANSFER EQUATION

摘要

A hybrid finite element/finite volume method was recently developed to solve the radiative transfer equation. In this method, the radiation intensity is approximated as a linear combination of basis functions, dependent only on the angular direction. The coefficients of the approximation are unknown functions of the spatial coordinates. The spatial discretization is carried out using the finite volume method, like in the discrete ordinates and finite volume methods, transforming the differential equations into algebraic equations. The angular discretization is accomplished using a methodology similar to that employed in the finite element method. The Galerkin-like approximation of the radiation intensity is introduced into the radiative transfer equation. Then, this is multiplied by the nth basis function and integrated over all directions, yielding a set of differential equations. The number of equations is equal to the number of terms in the summation. The basis functions are taken as the bilinear basis functions used in the finite element method, and a classical polar/azimuthal discretization is carried out, like in the finite volume and discrete transfer methods. However, while in these methods the radiation intensity is constant over a control angle or a solid angle, respectively, in the present method the radiation intensity is a continuously varying function, because the basis functions vary continuously within the control angle elements. Previous development and application of the method was limited to Cartesian coordinates. In the present work, the method is extended to complex geometries using a structured body-fitted mesh. Radiative transfer is calculated for several two-dimensional enclosures containing emitting-absorbing, scattering, grey media, and the predicted results are compared with benchmark solutions published in the literature. It was found that the results are in good agreement with reference solutions, demonstrating the ability of the present method to handle complex geometries.