| Summary: | A realistically dimensioned polystyrene model of a black-tailed deer was constructed and
tested in two forest stands and a wind tunnel to determine heat transfer relationships for
the boundary layer and coat. Heat transfer from the elliptically cross-sectioned model
deer trunk without a coat, in cross flow, was nearly the same as that for a circular
cylinder. Heat transfer from the model in longitudinal flow was somewhat larger than in
cross flow. Boundary layer conductance was not significantly different when the model
was covered by a real deer coat. Turbulence in the forest stands enhanced conductance
by about 30% for the cross flow orientation.
Insulation provided by the deer's coat was much larger than that provided by the
boundary layer, except in nearly calm conditions. The depth of a coat was found to
be an important determinant of its insulation value and thus piloerection may be an
important mechanism of thermoregulation. Free convection accounted for a significant
proportion of heat transfer within the coat, while radiative transfer through the coat and
conduction along individual hairs was relatively unimportant. Forced convection had
only a limited effect on heat transfer within the coat at wind speeds less than 8 m s - 1 .
There was no evidence of any turbulent enhancement of coat conductance in the forest
stands at the low wind speeds observed.
In order to estimate the radiative conductivity through the deer coat in the case of
piloerection, it was necessary to used a numerical integration procedure. An approximate
method for determining radiative conductivity, recommended in the literature, was found
to be unsatisfactory for the case of piloerection.
A model which predicts deer standard operative temperature and metabolic rates for various forest habitats was tested. The model illustrated the importance of the deer's
coat insulation in limiting heat loss and demonstrated the need for more research on the
coat conductance of live deer. For the winter data set used in model testing, daily average
metabolic requirements for a deer were similar in an old-growth stand and an adjacent
open area. It is desirable however, to calculate hourly outputs for different habitats to
determine the optimal microclimates for deer at different times of the day.
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