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

Inclined Cavity-3D time-dependent simulations 224
shown in the time-averaged temperature profiles along the centreline, con-
ditions are practically isothermal at the core with steep gradients across the
near-wall regions. This is again a consequence of the mixing caused by the
three-dimensional, unsteady flow structures.
In Figure 7.29, the profiles of the longitudinal, y direction, component of
the time-averaged mean velocity along traverses in the spanwise, z, direction
and half-way between the two thermally active sides, X=0.5, are compared
with corresponding experimental data. The experimental data, which extend
to just over half the spanwise distance, show a nearly sinusoidal variation,
with two negative peaks, one near the wall and one in the middle of the cavity
and a positive peak in between. Cooper et al. [8] argues that, assuming sym-
metric behaviour in the spanwise direction, this suggests the presence of four
longitudinal recirculation cells within the plane parallel to the thermally active
sides, which extend over the entire length of the cavity. The predicted profiles,
with the exception of the region near the lower end wall, Y=0.1, are reasonably
close to the data. The k-ε-AWF URANS, thus is able to return organised lon-
gitudinal re-circulation cells within the plane parallel to the thermally active
sides, but not necessarily four, which is what is suggested by the data. Fig-
ure 7.30, compares the profiles of the component of the time-averaged velocity
normal to the thermally active planes, x direction, along traverses in the span-
wise, z, direction and half-way between the two thermally active sides, X=0.5.
The experimental data show that the wall-normal, U, component is stronger
than the wall-parallel, V , component, plotted in Figure 7.29. In common with
the wall-parallel component, the wall normal also exhibits a nearly sinusoidal
variation in the spanwise direction, with negative peaks near the side wall and
the centre of the cavity and a positive peak in between. Once again the exper-
imental spanwise traverses do not extent over the entire width of the cavity,
but assuming that the two halve are symmetric, Esteifi suggests that these data
indicate the presence of four vortices which extend over the entire length of
the inclined cavity. At the middle of the cavity, Y=0.5, the spanwise profile
returned by the k-ε-AWF, is close to the available data and also returns a sym-
metric distribution in the spanwise direction. The three dimensional URANS
with the k-ε-AWF is thus able to reproduce the most dominant feature of the