Doctoral Dissertations


"The discrete ordinates method has evolved as a powerful tool in the analysis of radiative heat transfer in multidimensional geometries containing participating media. The discrete ordinates method does not make accurate predictions in situations involving isolated boundary sources, due to a phenomenon known as 'ray-effects'. A modified discrete ordinates (MDO) method is presented. The intensity is broken into diffuse and direct components. The direct intensity component is determined analytically, and the direct inscatter term appears as a distributed source in the transport equation for the diffuse intensity. The diffuse transport equation is solved numerically by the conventional discrete ordinates procedure.

The MDO method is applied to solve the radiative transfer equation in two- and three-dimensional rectangular and cylindrical enclosures containing absorbing, emitting, and isotropically scattering media. Uniform and non-uniform diffuse loadings on the top boundary are considered. Graphical and numerical results for various geometries and loading parameters are presented. The standard discrete ordinates solution exhibits anomalies in the flux leaving the bottom. Large errors are observed when the loading area is small compared to the overall enclosure dimensions. The MDO method eliminates 'ray-effects' and significantly improves the accuracy of the predictions"--Abstract, page iv.


Crosbie, A. L. (Alfred L.)

Committee Member(s)

Nelson, Harlan F., 1938-2005
Look, Dwight C., 1938-
Hale, Barbara N.
Edwards, D. R.


Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Mechanical Engineering


University of Missouri--Rolla

Publication Date

Spring 1995

Journal article titles appearing in thesis/dissertation

  • Modified discrete ordinates solution of radiative transfer in two-dimensional rectangular enclosures
  • Modified discrete ordinates solution of radiative transfer in three-dimensional rectangular enclosures
  • Modified discrete ordinates solution of radiative transfer in axisymmetric cylindrical enclosures
  • Modified discrete ordinates solution of radiative transfer in three dimensional cylindrical enclosures


xix, 274 pages

Note about bibliography

Includes bibliographical references.


© 1995 Mohan Ammanath Ramankutty, All rights reserved.

Document Type

Dissertation - Restricted Access

File Type




Subject Headings

Radiative transfer
Transport theory -- Discrete ordinates method
Boundary value problems
Discrete groups -- Data processing

Thesis Number

T 6906

Print OCLC #


Electronic OCLC #


Link to Catalog Record

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