The computation of turbulent natural convection flows - Turbulence ...

157
2
k/V0 2
k/V0 0.03
0.02
0.01
LRN
X=0.5
x
x
15 unstable
10 unstable
5 unstable
0 unstable
x
x
0 xxxxx xxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxx xxxx x
0 0.2 0.4 0.6 0.8 1
Y/L
0.03
0.02
0.01
SWF
X=0.5
0
0 0.2 0.4 0.6 0.8 1
Y/L
x
15 unstable
10 unstable
5 unstable
0 unstable
2
k/V0 2
k/V0 0.0015
0.001
0.0005
AWF
X=0.5
0
0 0.2 0.4 0.6 0.8 1
Y/L
0.014
0.012
0.01
0.008
0.006
0.004
0.002
RSM-basic
X=0.5
15 unstable
10 unstable
5 unstable
0 unstable
0
0 0.2 0.4 0.6 0.8 1
Y/L
5 unstable
0 unstable
Figure 6.24 – k profiles along the section at X=0.5 at different angle of inclinations
resulting from k-ε using LRN, AWF, SWF and RSM-Basic using AWF.
6.4 Inclined tall cavity -60 ◦ stable
6.4.1 Flow Pattern (including comparison with90 ◦ case)
The predicted flow pattern inside the60 ◦ stable inclined tall cavity is shown
in Figures 6.25-6.26. In this test case,because of the temperature difference
between the tall walls, air near the hot wall moves up and then impinges on to
the top insulated wall and moves over the top insulated wall, until it impinges
on to the cold wall and becomes cold and moves down. The air then moves
down the cold wall and impinges on to the bottom insulated wall, changes
direction and flows over the bottom wall until it impinges on to the hot wall.
This creates a single cell circulation inside the inclined tall cavity. Figure 6.25
shows that there is turbulent flow in the cavity core. The temperature contours
reveal that most of the temperature change from the hot to the cold side is
confined to the thin layers along the two thermally active walls, with only a
gentle temperature change across the cavity core.