Recent Developments in the Solution of Radiation Heat Transfer Using the Discrete Ordinates Method

1998 ◽  
Vol 25 (4-6) ◽  
pp. 556-567 ◽  
Author(s):  
John C. Chai ◽  
H. S. Lee ◽  
Suhas V. Patankar
Keyword(s):  
Heat Transfer ◽  
Radiation Heat Transfer ◽  
Discrete Ordinates ◽  
Radiation Heat ◽  
Discrete Ordinates Method ◽  
Recent Developments

Discrete Ordinates Method for Transient Radiation Transfer in Cylindrical Enclosures

2003 ◽  
Author(s):  
Kyunghan Kim ◽  
Zhixiong Guo
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Radiative Heat ◽  
Radiation Transfer ◽  
Radiation Heat Transfer ◽  
Discrete Ordinates ◽  
Radiation Heat ◽  
Discrete Ordinates Method ◽  
Transient Radiation ◽  
Tissue Welding

The Discrete Ordinates Method (DOM) for solving transient radiation transfer equation in cylindrical coordinates is developed for radiation heat transfer in participating turbid media in pico-scale time domain. The application problems addressed here are laser tissue welding and soldering. The novelty of this study lies with the use of ultrashort laser pulses as the irradiation source. The characteristics of transient radiation heat transfer in ultrafast laser tissue welding and soldering are studied with the DOM developed. The temporal distribution of radiative energy inside the tissue cylinder as well as the radiative heat flux on the tissue surface is obtained. Comparisons are performed between laser welding without use of solder and laser soldering with use of solder. The use of solder is found to have highly concentrated radiation energy deposition in the solder-stained region and reduce the surface radiative heat flux accordingly. Comparisons of transient radiation heat transfer between the spatially square-variance and Gaussian-variance laser inputs and between the temporally Gaussian and skewed input profiles are also conducted.

scholarly journals Reduced Order Modeling Applied to the Discrete Ordinates Method for Radiation Heat Transfer in Participating Media

2016 ◽  
Author(s):  
John Tencer ◽  
Kevin Carlberg ◽  
Roy Hogan ◽  
Marvin Larsen
Keyword(s):  
Heat Transfer ◽  
Radiation Heat Transfer ◽  
Practical Interest ◽  
Accurate Solution ◽  
Discrete Ordinates ◽  
Test Problems ◽  
Radiation Heat ◽  
Reduced Basis ◽  
Participating Media ◽  
Discrete Ordinates Method

Radiation heat transfer is an important phenomenon in many physical systems of practical interest. When participating media is important, the radiative transfer equation (RTE) must be solved for the radiative intensity as a function of location, time, direction, and wavelength. In many heat transfer applications, a quasi-steady assumption is valid. The dependence on wavelength is often treated through a weighted sum of gray gases type approach. The discrete ordinates method is the most common method for approximating the angular dependence. In the discrete ordinates method, the intensity is solved exactly for a finite number of discrete directions, and integrals over the angular space are accomplished through a quadrature rule. In this work, a projection-based model reduction approach is applied to the discrete ordinates method. A small number or ordinate directions are used to construct the reduced basis. The reduced model is then queried at the quadrature points for a high order quadrature in order to inexpensively approximate this highly accurate solution. This results in a much more accurate solution than can be achieved by the low-order quadrature alone. One-, two-, and three-dimensional test problems are presented.

Radiation Heat Transfer in Fluidized Beds: A Comparison of Exact and Simplified Approaches

1994 ◽  
Vol 116 (3) ◽  
pp. 652-659 ◽  
Author(s):  
G. Flamant ◽  
J. D. Lu ◽  
B. Variot
Keyword(s):  
Heat Transfer ◽  
Fluidized Beds ◽  
Radiation Heat Transfer ◽  
Discrete Ordinates ◽  
Transfer Model ◽  
Radiation Heat ◽  
Flux Divergence ◽  
Transfer Coefficients ◽  
Variable Porosity ◽  
Radiation Exchange

Radiation heat transfer at heat exchanger walls in fluidized beds has never been examined through a complete formulation of the problem. In this paper a wall-to-bed heat transfer model is proposed to account for particle convection, gas convection, and radiation exchange in a variable porosity medium. Momentum, energy, and intensity equations are solved in order to determine the velocity, temperature, radiative heat flux profiles and heat transfer coefficients. The discrete-ordinates method is used to compute the radiative intensity equation and the radiative flux divergence in the energy equation. Both the gray and the non-gray assumptions are considered, as well as dependent and independent scattering. The exact solution obtained is compared with several simplified approaches. Large differences are shown for small particles at high temperature but the simplified solutions are valid for large particle beds. The dependency of radiative contribution on controlling parameters is discussed.

The Effect of Radiation on Oxy-Fuel Combustion Characteristics in Microchannels

2013 ◽  
Vol 302 ◽  
pp. 49-54
Author(s):  
Rached Ben-Mansour ◽  
Mohamed A. Habib ◽  
Pervez Ahmed
Keyword(s):  
Heat Transfer ◽  
Diffusion Flames ◽  
Radiation Heat Transfer ◽  
Fuel Combustion ◽  
Combustion Characteristics ◽  
Discrete Ordinates ◽  
Small Scale ◽  
Transfer Model ◽  
Radiation Heat ◽  
Radiation Model

The importance of thermal radiation in heat transfer mechanism in many micro combustion systems has been well identified in the past few years. There is currently lack of quantitative understanding on the radiation heat transfer in relatively small scale laminar diffusion flames in microchannels. In the present study a two dimensional model is considered to investigate the effects of radiation on oxy-fuel combustion characteristics in microchannels. The discrete-ordinates radiation model is used for the study. It is observed that excluding radiation model results in the over-prediction of combustion temperatures in the micro-reactor. It has also been observed that the overall reaction rate and its peak value increase when accounting for radiative heat transfer, despite the decrease in temperature caused by radiation. Therefore, it is important to incorporate a radiation heat transfer model in combustion micro-systems in order to predict their characteristics accurately.

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