Isotherms of Natural and Forced Convection Around a Heated Horizontal Cylinder Embedded in a Porous Medium - Selected Topics of Computational and Experimental Fluid Mechanics - page 228

Fig. 8 Plot showing the
resulting temperature
distributions for different
angles of injection as a
function of length (length
taken with reference to the
vertical z -axis passing
through at the heat source)
deformation attained in this later case was larger than that observed in Fig. 5 .This
may be due to the induced air stream going to the same direction as the buoyant
forces.
In the last part of the experiments different plumes were obtained by inducing the
air stream at different angles, as referred to the positive vertical z -axis and measured
clockwise, and by placing the origin at the center of the heat source. The steady
configuration adopted by the plumes is shown in Fig. 7 . The shape of these plumes is
strongly influenced by the direction of the induced stream. InFig. 8 , the corresponding
values of temperature for each of these later cases were plotted as a function of length.
6 Conclusions
The resulting buoyant plumes or isotherms around a heated source, due to free
and forced convection acting on a heated cylinder buried in an air-saturated porous
medium, have been experimentally studied by using infrared thermography. Infrared
thermography allowed to observe the overall evolution of the buoyant plumes, since
the phenomenon was governed by conduction from zones close to the heated source
to zones where the convection effects dominate. As we have seen by comparing the
effect of a continuous stream with the pure convection case, the shapes adopted by
the buoyant plumes, are were strongly affected by the action of the continuous air
flow. We do not find any important correlation with the rate of air injected. The final
shape of the plumes indicates that the stream lines of the flow change their trajectory
in zones nearby the heat source. Finally, the actual study agrees with the main the-
oretical predictions, of Kurdyumov and Liñán ( 2001 ), for the isotherms during free
and forced convection. Incidentally, this kind of studies can be useful, for instance,