Verlag des Forschungszentrums Jülich
JUEL-2870
Mika, Klaus; Funk-Kath, Ursula
Analytical results for a class of view factors occuring in the vertical Bridgman method
55 S., 1994
S ummary
The treatment of radiation heat transfer in the Computer modeiling of crystal growth
from the faselt requires the net heat flux q2 for the boundary conditions of the temperature
field, and the view factors fij for the radiative exchange between surfaces
Ai, Aj of an enclosure, i, j = 1 to N. Different methods can be used to determine qi :
the radiosity method, a direct and Gebhart's method . A new proof of the equivalence
of Gebhart's method with the other two is given . The concept of view factors
for gray-diffuse surfaces is briefly surveyed . For a simplified enclosure describing
the interior part of a Vertical Bridgman furnace the fij are determined within an
analytical approximation . The convergence of this method is investigated for two
Singular cases : (i) A. and A; have a common edge, (ii) A, is self-viewing . As the
main result we present, for a coaxial enclosure partitioned into rings, the fij in closed
form by means of the Sparrow-Moon area-contour integral . lt is further shown, that
Sparrow's double contour integral is not generally applicable, if shadowing effects
are present
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