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

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the spanwise direction, suggests the presence of four longitudinal recircula-
tion 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.
There is close agreement between the predictions and the measurements, both
in terms of the levels and the distributions of the Nusselt number in the longi-
tudinal and spanwise directions, except for an over-estimation of the Nusselt
number levels along the cold wall at Z=0.5 (at the middle in the spanwise di-
rection). The comparisons also showed that the 3D URANS k-ε-AWF predic-
tions are able to reproduce the range of dominant frequencies and their power
densities. Therefore the three dimensional URANS with the k-ε-AWF is able
to reproduce the most dominant feature of the flow at this angle of inclination.
The Basic version of the RSM with the Analytical Wall Function was then
used to simulate the 15 ◦ unstable inclined cavity. The comparisons showed
close agreement between the experimental and numerical mean temperature.
The mean velocity profiles within the x-y plane resulting from the RSM-Basic
were similar to those which resulted from the use of the k-ε-AWF. This is ex-
pected because the flow in the x-y plane is weak and both turbulence models
produce almost the same velocity profiles. The k-ε-AWF predicted 4 longitu-
dinal vortices, the sizes and strength of which varied from the bottom to top of
the cavity. The RSM on the other hand produced 3 longitudinal vortices, the
sizes and strength of which were almost constant from the bottom to top of
the cavity, a feature that is closer to experimental findings. The Basic RSM pre-
dicted normal turbulent stresses which were in closer agreement with the mea-
surements than the corresponding k-ε-AWF profiles. This is not unexpected,
since the RSM represents exactly physical processes like the production rate
and the convection of each stress component, and it approximate the effects
of others, like the dissipation rate and the redistribution of turbulence energy
among the three directions. The comparisons showed that the RSM Nu pre-
dictions, like the k-ε ones, were in close agreement with most of the available
data, even at the central, Y=0.5, location. The comparisons showed that the
time-dependent RSM well-predicted the range of dominant frequencies and
their power densities compared with the experimental data, similarly with the