Computer program computes temperature distribution as a function of time in a given body which has been subdivided into a network of nodes. Thermal resistances and capacitances may be computed from nodal geometry

Elkin, R.

Mc Garrity, A. L.

English

NASA Technical Reports Server

September 1967	 Brif 67-10329 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Computer Program Resolves Radiative, Conductive, and Convective Heat

Transfer Problems for Variety of Geometries 
A computer program has been developed that com-
putes temperature distribution as a function of time 
in a given body which has been subdivided into a 
network of nodes. The nodes may be numbered arbi-
trarily but the program is presently limited to 100 
nodes. 
Methods of heat transfer between nodes may be 
either conduction, convection, or radiation, and pro-
vision for fluid nodes is included. Thermal properties 
and boundary conditions may vary with time. Ther-
mal resistances and capacitances may be computed by 
program from nodal geometry. 
The program solves the problem by generating a 
system of first order differential equations and ob-
taining an incremental solution by using a method of 
backward finite differences. 
Before it is possible to prepare input data for this 
program, it is necessary to subdivide the body under 
consideration into a reasonable number of subele-
ments called nodes. The nodes must be either of two 
shapes, namely a rectangular parallelepiped or prism. 
These two shapes are defined as follows. 
Rectangular Parallelepiped: a solid whose surface 
is made up of three pairs of parallel faces, each of 
which is either a rectangle or a square. 
Prism: a solid whose surface is made up of three 
pairs of opposite sides, one pair of which is parallel 
(but not necessarily identical) rectangles, whose edges 
are parallel in pairs. An additional asumption is that
a line connecting the centroids of the two parallel 
rectangles is normal to both. Thus the other four sides 
are right trapezoids, each being congruent to the one 
directly across from itself. 
Node numbers are positive integers less than 100, 
may be assigned arbitrarily, and need not be consecu-
tive. Each face of a node must touch only one other 
node face, and their respective surfaces must coin-
cide exactly. Thus each node may connect with no 
more than 6 other nodes; in fact 6 and only 6 connec-
tions for each node are assumed. In the event that 
some of the connections are not used, dummy con-
nections must be provided to bring the number to 6. 
Notes: 
I. The program has been developed for the IBM 7094 
- and the programming language is Fortran IV. 
2. Inquiries concerning this program may be di-
rected to:
COSMIC 
Computer Center 
University of Georgia 
Athens, Georgia 30601 
Reference: B67-10329 
Patent status: 
No patent action is contemplated by NASA. 
Source: A. L. McGarrity and R. Elkin 
of Marshall Space Flight Center 
(MFS-19l0) 
Category 06 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
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Computer program resolves radiative, conductive, and convective heat transfer problems for variety of geometries

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