Environmental Engineering Reference
In-Depth Information
1.2 Application of the Atmospheric Model RAMS
to Simulate High Resolution Urban Flow: Validation
with the MUST Case
T.G. Reisin
1
and S. Trini Castelli
2
1
Soreq Nuclear Research Center, Yavne, Israel
2
Institute of Atmospheric Sciences and Climate, National Research Council, Torino, Italy
Abstract
The latest version of RAMS regional model has been modified and
applied to describe the flow circulation and tracer dispersion in an idealized urban
environment at high resolution. A particular attention was dedicated to the critical
role played by the turbulence closure, considering two alternative versions of the
k-ε scheme. Here, the model performance and the effect of the two turbulence
closures on flow and dispersion are tested for the MUST Experiment Case. Results
of flow and concentration patterns and sensitivity to the turbulence closures are
presented and discussed.
Keywords
Meteorology modelling, urban flow, turbulence parameterization, MUST
experiment
1. Description of the Case Study
In the frame of COST732 Action, the last version of the atmospheric model
RAMS (RAMS6) has been tested on the MUST Field Experiment. RAMS is a
well known atmospheric model, which simulates atmospheric processes on scales
from an entire hemisphere down to the microphysics in the planetary boundary
layer (Cotton et al., 2003). The goal of this study is to evaluate the possibility of
using a regional meteorological modeling system to describe the flow and pollu-
tant dispersion in an urban environment, characterized by short time (min) and
space (hundreds of meters) scales, and by the presence of obstacles. More speci-
fically, the aim here is to test the RAMS model, configured in a CFD-like mode
and high resolution grid (~1 m grid space), in simulating the flow dynamics and
tracer dispersion in the presence of obstacles.
The RAMS model originally uses turbulence parameterisations that are suitable
to atmospheric flow. In past years, a standard version of the k-∑ turbulence closure
(Trini Castelli et al., 2001) and the renormalization group (RNG) k-∑ turbulence
model (Reisin et al., 2007; Trini Castelli and Reisin, 2008) were implemented and
tested in RAMS. These closures belong to the type typically used in CFD models.
