Surface Radiation Exchange for Two-Dimensional Rectangular Enclosures Using the Discrete-Ordinates Method

1992 ◽  
Vol 114 (2) ◽  
pp. 465-472 ◽  
Author(s):  
A. Sa`nchez ◽  
T. F. Smith
Keyword(s):  
Weighting Factor ◽  
Heat Fluxes ◽  
Surface Radiation ◽  
Discrete Ordinates ◽  
Two Dimensional ◽  
Discrete Ordinates Method ◽  
Radiation Exchange ◽  
Radiant Exchange ◽  
Irregular Geometries ◽  
Good Agreement

The purpose of this study is to develop a model based on the discrete-ordinates method for computing radiant exchange between surfaces separated by a transparent medium and to formulate the model so that arbitrary arrangements of the surfaces can be accommodated. Heat fluxes from the model are compared to those based on the radiosity/irradiation analysis. Three test geometries that include shadowing and irregular geometries are used to validate the model. Heat fluxes from the model are in good agreement with those from the radiosity/irradiation analysis. Effects of geometries, surface emittances, grid patterns, finite-difference weighting factor, and number of discrete angles are reported.

Schemes and Applications of First and Second-Order Discrete Ordinates Interpolation Methods to Irregular Two-Dimensional Geometries

1997 ◽  
Vol 119 (4) ◽  
pp. 730-737 ◽  
Author(s):  
H.-M. Koo ◽  
K.-B. Cheong ◽  
T.-H. Song
Keyword(s):  
Exact Solutions ◽  
Second Order ◽  
Heat Fluxes ◽  
Discrete Ordinates ◽  
Analysis Tool ◽  
Two Dimensional ◽  
Numerical Schemes ◽  
Emissive Power ◽  
Square Enclosure ◽  
Good Agreement

This paper presents numerical schemes and comparison of predictions of radiative heat transfer for the first and the second order discrete ordinates methods (DOM1 and DOM2) using an interpolation scheme. The formulations are followed by derivation of numerical schemes for two-dimensional body fitted grids. With varying the optical depths and the numbers of grids and ordinates, radiative wall heat fluxes by DOM1 and DOM2 are calculated to compare with the exact solutions for three kinds of two-dimensional enclosures (square, quadrilateral, and J-shaped) containing absorbing/emitting and nonscattering media of known temperature with cold black walls. Emissive power and radiative wall heat fluxes by DOM1 and DOM2 are calculated to compare with zonal results for two-dimensional square enclosure containing absorbing/emitting and isotropically scattering medium of known uniform heat source with cold black walls. The results of DOM1 and DOM2 are in good agreement with the exact solutions or the zonal results. DOM1 gives more accurate results than DOM2 for most of the tested optical depths and the numbers of grids and ordinates. These methods appear as powerful candidates of very versatile radiation analysis tool. Their grid and ordinate dependencies are also discussed in depth.

Numerical Modeling of Radiative and Reactive Flow Field Around a Blunt Body at Hypersonic Regimes

2010 ◽  
Author(s):  
Morteza Rahmanpour ◽  
Reza Ebrahimi ◽  
Mehrzad Shams
Keyword(s):  
Flow Field ◽  
Differential Equations ◽  
Heat Fluxes ◽  
Transitional Flow ◽  
Navier Stokes ◽  
Implicit Time ◽  
Discrete Ordinates ◽  
Two Dimensional ◽  
Fully Implicit ◽  
Time Marching

A numerical method for calculation of strong radiation for two-dimensional reactive air flow field is developed. The governing equations are taken to be two dimensional, compressible Reynolds-average Navier-Stokes and species transport equations. Also, radiation heat flux in energy equation is evaluated using a model of discrete ordinate method. The model used S4 approximation to reduce the governing system of integro-differential equations to coupled set of partial differential equations. A multiband model is used to construct absorption coefficients. Tangent slab approximation is assumed to determine the characteristic parameters needed in the Discrete Ordinates Method. The turbulent diffusion and heat fluxes are modeled by Baldwin and Lomax method. The flow solution is obtained with a fully implicit time marching method. A thermochemical nonequilibrium formulation appropriate to hypersonic transitional flow of air is presented. The method is compared with existing experimental results and good agreement is observed.

Experimental and Numerical Studies of Short Pulse Propagation in Model Systems

2002 ◽  
Author(s):  
Sunil Kumar ◽  
Zhixiong Guo ◽  
Janice Aber ◽  
Bruce Garetz
Keyword(s):  
Monte Carlo ◽  
Pulse Propagation ◽  
Short Pulse ◽  
Model Systems ◽  
Discrete Ordinates ◽  
Pulsed Lasers ◽  
Discrete Ordinates Method ◽  
Numerical Studies ◽  
Tissue Phantoms ◽  
Good Agreement

In this paper experimental and numerical studies of the propagation of short-pulsed lasers through scattering and absorbing media are presented. Experimental results of a 60 ps pulse laser transmission in tissue phantoms are obtained and compared with Monte Carlo simulations. Good agreement between the Monte Carlo simulation and experimental measurement is found. Three models are developed for the simulation of short pulse transport. Benchmark comparisons among the Monte Carlo (MC), transient discrete ordinates method (TDOM) and transient radiation element method (TREM) are conducted.

Nongray Radiative Gas Analyses Using the S-N Discrete Ordinates Method

1991 ◽  
Vol 113 (4) ◽  
pp. 946-952 ◽  
Author(s):  
T. K. Kim ◽  
J. A. Menart ◽  
H. S. Lee
Keyword(s):  
Radiative Heat ◽  
Narrow Band ◽  
Wide Band ◽  
Heat Fluxes ◽  
Discrete Ordinates ◽  
Band Model ◽  
Spectral Correlation ◽  
Discrete Ordinates Method ◽  
Computational Speed ◽  
Wide Band Model

The S-N discrete ordinates method is applied to analyze radiative heat transfer in nongray gases. Spectral correlation between the terms in the equation of transfer is considered for black or nearly nonreflecting walls. Formulations to apply the S-N method using a narrow-band or the exponential wide-band model are presented. The net radiative wall heat fluxes and the radiative source distributions are obtained for uniform, parabolic, and boundary layer type temperature profiles, as well as for a parabolic concentration profile. The narrow- and wide-band nongray solutions are compared with gray-band approximations using the same band models. The computational speed of the gray-band approximation is obtained at the expense of accuracy in the internal fluxes and radiative source distributions. The wall radiative flux predictions by the gray-band approximation are satisfactory.

Discrete-Ordinates Solutions of the Radiative Transport Equation for Rectangular Enclosures

1984 ◽  
Vol 106 (4) ◽  
pp. 699-706 ◽  
Author(s):  
W. A. Fiveland
Keyword(s):  
Heat Transfer ◽  
Transfer Rate ◽  
Numerical Solutions ◽  
Surface Heat ◽  
Discrete Ordinates ◽  
Two Dimensional ◽  
Scattering Medium ◽  
Discrete Ordinates Method ◽  
Radiant Intensity ◽  
Radiative Transport Equation

The Sn discrete-ordinates method is used to find numerical solutions in a two-dimensional rectangular enclosure with a gray absorbing, emitting, and isotropically scattering medium. Results are obtained for the S2, S4, and S6 approximations that correspond to 4, 12, and 24 flux approximations, respectively, and are compared with exact solutions, numerical Hottel’s zone results, P3 differential approximations, and an approximation method developed by Modest. The S2 approximation solutions were found to be applicable only for several specific cases and are not recommended for general use. The S4 and S6 solutions compare favorably with other methods and can be used to predict radiant intensity and surface heat transfer rate for various surface and optical conditions.

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