Environmental Engineering Reference
In-Depth Information
In
Fig. 2
an example of the vertical profiles of speed, turbulent kinetic energy
(t.k.e.) and concentration is plotted for tower T (see location in
Fig. 1)
. In the
present case the standard k-∑ and RNG-k∑ closures produce similar wind speeds,
showing relatively small differences. In general, both schemes predict values that
compare well with the few observed values. However, the standard k-∑ scheme
produces always higher t.k.e. values than RNG-k ∑ and better reproduces the few
observed values at the lower levels. Above 10 m height, the measured t.k.e. at T
tower is not captured and the k-∑ simulated profiles slowly reach their minimum
values. The predicted concentrations have similar values to the observed one, but
the shapes of their profiles are different and the maximum is found at different
heights. Comparisons with field concentration data are also presented in
Fig. 3
,
where predictions are plotted versus the observations at the sensors displaced
along the rows of the container arrays, at 1.6 m height. In general, simulations
better match the observed data at the surface samplers than at the vertical profiles.
The agreement between RAMS6-mod and observed fields is better with k-ε
standard scheme close to the source, rows JI and HG, while at the farthest row,
DC, RNG-k∑ run is superior. The location and magnitude of the maximum value
is generally captured, while the spread of the plume is not well reproduced, espe-
cially at the southern part of the domain (negative Y values). This can be explained
by a deviation of the plume centerline with respect to the upwind direction that
is larger in the reality than in the simulation. This means that the RAMS6-mod
meteorological wind and turbulence fields may have not fully reproduced the
characteristics of the correspondent observed fields in the obstacles array.
Fig. 3.
Concentration at the samplers along the obstacles array rows. Line + squares: observations,
line + triangles: k-∑ run; line + circles: RNG-k∑ run
References
J.Y. Harrington, and M.E. Nicholls, 2003: RAMS 2001 - Current status and future directions.
Meteor. Atmos. Phys, 82, 5-29.
