Environmental Engineering Reference
In-Depth Information
clockwise vortex located after the step of the cavity; the second vortex appears after
the heater of the cavity with a clockwise rotation. These two vortices are formed as a
result of the boundary layer detachment from the surface driven by the fluid motion
that crosses the cavity. At the superior right corner, a thirdweak, anti-clockwise vortex
emerges from the impingement of the fluidwith the corner. Furthermore, for Re
50
the same vortex distribution can be observed (see bottom panel). However, the size of
the vortices is increased. The main vortex extends over the heater affecting the energy
and mass transport inside the cavity. The jet emerges horizontally from the flow inlet
of the cavity, but as it moves ahead of its horizontal component decreases and the
vertical component increases due to the change of the transversal area of the cavity.
Figure 3 shows the isotherms for W p
=
=
W
/
5. The top panel shows the thermal
behavior of the fluid inside the cavity for Re
=
10, while the bottom panel is for
50. It can be seen that the temperature contours are clustered around the heater,
and a hot temperature region grows toward the middle of the cavity due to the thermal
plume that heats the fluid in the neighborhood of the heater. However, beyond this
region the contours tend to elongate from the heater toward the exit of the cavity and
they also spread toward the interior part of the cavity with smaller values since the
fluid is cooled as a result of the flow motion that crosses the cavity. Increasing the
Reynolds number, a stronger disturbance of the contours can be appreciated behind
the heater. Furthermore, for a higher Reynolds number the thermal plume does not
completely ascend up to the top part of the cavity, instead it is dispersed towards the
exit of the cavity.
For Re
Re
=
=
50, the fluid behind the heater is hotter than the fluid in front of it, hence,
the left region of the heater can have a higher heat generation rate. For Re
=
10,
the fluid in front of the heater is hotter than the fluid behind the heater, and hence,
the right region of the heater can have a higher heat generation rate. However, we
note that in both cases the temperature decreases away from the heater, and the
maximum temperature occurs in the layer of fluid adjacent to the heater. For the low
Reynolds number stratification can be observed in the isothermal; and the lower the
Fig. 3
Isotherms for W p =
W
/
5. To p R e
=
10. Bottom Re
=
50
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