A massively parallel solution strategy for efficient thermal radiation simulation
Résumé
A novel and efficient methodology to solve the Radiative Transfer Equations (RTE) in thermal radiation is discussed. The BiCGStab(2) iterative solution method, as designed for the non-symmetric linear equation systems, is used to solve the discretized RTE. The numerical upwind and central schemes are blended to provide a stable numerical scheme (MUCS) for interpolation of the cell facial radiation intensities in finite volume formulation. The combination of the BiCGStab(2) and MUCS methods proved to be very efficient when coupling with the DOM approach to solve the RTE. A cost-effective tabulation technique for the gaseous radiative property model SNB-FSCK using 7-point Gauss-Labatto quadrature scheme is also introduced. The whole methodology is implemented into a massively parallel unstructured CFD code where the radiative and fluid flow solutions share the same domain decomposition, which is the bottleneck in current radiative solvers. The dual mesh decomposition at the cell groups level and processors level is adopted to optimize the CFD code for massively parallel computing. The whole method is applied to simulate the radiation heat-transfer in a 3D rectangular enclosure containing non-isothermal CO2 and H2O mixtures. Two test cases are studied for homogeneous and inhomogeneous distributions of CO2 and H2O in the enclosure. The result is reported for the heat flux and radiation energy source and the comparison is also made between the present methodology BiCGStab(2)/MUCS/tabulated SNB-FSCK, the benchmark method SNB-CK (implemented at 25cm−1 narrow-band) and some other methods available in the literature. The present method (BiCGStab(2)/MUCS/tabulated SNB-FSCK) yields more accurate predictions particularly for the radiation source term. When comparing with the benchmark solution, the relative error of the radiation source term is remarkably reduced to less than 4% and the CPU time is drastically diminished.