A narrow band model based on the absorption coefficient and its application to the calculation of radiative transfer in two-dimensional enclosures

Abstract

In a recent article (Fisher and Rani, Vol. 277, JQSRT, 2022), we presented a narrow band model (NBM) with the absorption coefficient as the fundamental radiative property and applied it to predict radiative heat transfer in one-dimensional (1-D) non-gray enclosures. In this communication, we investigate the accuracy of the NBM in computing radiative transfer in two-dimensional (2-D) non-gray enclosures. Radiative fluxes normal to walls and flux divergences computed from NBM simulations are compared with results obtained using three spectral methods: line-by-line (LBL) calculations that serve as the benchmark, wavenumber-selective line-by-line (WS-LBL) calculations, and the spectral line-based weighted sum of gray gases (SLW) method. The gaseous medium in the 2-D rectangular enclosures is non-isothermal and inhomogeneous, with the participating species consisting of CO2, or H2O, or a mixture of CO2 and H2O. It is seen that the presence of CO2 enhanced the accuracy of NBM predictions due to the higher optical thickness of CO2 relative to that of H2O. The predictions of WS-LBL calculations are also in good agreement with LBL data.