Radiative heat transfer simulation of inhomogeneous and non-gray medium based on FSCK and NCMCM

The radiative heat transfer in high-temperature combustion systems is often non-negligible but challenging to simulate due to the complexity of solving the radiative transfer equation and the strong spectral selectivity and inhomogeneity. To overcome the above problems, a solution based on full-spectrum correlated k-distribution method (FSCK) and null-collision Monte Carlo method (NCMCM) is proposed in this paper. Compared to traditional photon Monte Carlo methods (PMCM), NCMCM can significantly reduce the tracking time in non-uniform media without affecting statistical results by introducing a null-collision event. By establishing the correlated assumption and using high-precision Gaussian quadrature scheme or random artificial spectral g-sampling method, FSCK can greatly reduce the number of solutions for the radiative transfer equation in non-uniform non-gray gases without losing spectral accuracy. The combination of FSCK and NCMCM can easily simulate radiative heat transfer in a non-uniform and non-grey media by merely introducing a non-gray stretching factor into the recorded blackbody radiation intensity. The computational accuracy and efficiency of two combination methods, FSCK/NCMCM and FSCK/PMCM, are evaluated through several typical cases. The results demonstrate that both FSCK/NCMCM with fixed artificial spectral g₀ sampling and FSCK/PMCM with random artificial spectral g₀ sampling achieve accuracy comparable to the benchmark method of LBL/NCMCM. FSCK/NCMCM exhibits stronger result stability for tracking more photon bundles per target element, while requiring only approximately half the computational time of FSCK/PMCM. Simultaneously, FSCK/NCMCM eliminates the process of pre-establishing and loading a R-g₀ database, thereby providing the advantage of lower memory overhead. Furthermore, when NCMCM and PMCM adopt identical random g sampling, the computational efficiency of FSCK/NCMCM proves to be several times higher than that of FSCK/PMCM.