Sharif Digital Repository

Discrete ordinates method relies on approximating the integral term of the transport equation with the aid of quadrature summation rules. These quadratures are usually based on certain assumptions which assure specific symmetry rules and transport/diffusion limits. Generally, these assumptions are not problem-dependent which results in inaccuracies in some instances. Here, various methods have been developed for more accurate estimation of the independent angle in S2 approximation, as it is tightly related to valid estimation of the diffusion coefficient/length. We proposed and examined a method to reduce a complicated problem that usually is consisting many energy groups and discrete... 

Discrete ordinates method relies on approximating the integral term of the transport equation with the aid of quadrature summation rules. These quadratures are usually based on certain assumptions which assure specific symmetry rules and transport/diffusion limits. Generally, these assumptions are not problem-dependent which results in inaccuracies in some instances. Here, various methods have been developed for more accurate estimation of the independent angle in S2 approximation, as it is tightly related to valid estimation of the diffusion coefficient/length. We proposed and examined a method to reduce a complicated problem that usually is consisting many energy groups and discrete... 

In this paper, the turbulent reacting flow in an industrial furnace is numerically simulated using the RANS equations. The two-equation standard k-ε and the eddy dissipation models are used respectively to close the turbulent closure problem and to consider the turbulence-chemistry interaction. The radiation transfer equation is solved using the discrete ordinates method (DOM). To calculate the radiation absorption coefficient in participating combustion gases, we use the spectral line-based weighted sum of grey gases (SLW) model and compare the achieved results with famous gray-based model, i.e., the weighted-sum-of-gray-gases (WSGG) model. The results of this research show that using the... 

Oxy-fuel combustion is a modern technique to improve the efficiency and reduce environmental penalty of many combustion systems. In the present study, three different approaches of skipping radiation, weighted sum of gray gases (WSGGM), and spectral line based weighted sum of gray gases (SLW) have been used in simulation of an unconfined turbulent bluff-body flame. The model is first validated against existing experimental data and then used to study the effect of oxygen enhancement and different spectral radiation models. Due to small optical thickness of the studied system, predictions of all three different approaches are close. However, by increasing oxygen concentration in the oxidizer...