Wind-field and pollution-dispersion simulation in a street canyon in Helsinki with ADREA-HF code

ADREA-HF, which is a Computational Fluid Dynamics (CFD) code, is utilised in order to
numerically study the flow and concentration fields within a street-canyon area. The selected
site is Runeberg Str., a typical urban street canyon with an aspect ratio of approximately 1:1
in Helsinki, Finland. The ADREA-HF model is a transient, non-hydrostatic, dense transport
code, especially developed for dispersion modelling of buoyant or passive gases over
complex terrain in local scale. It solves the 3D unsteady Reynolds Averaged Navier-Stokes
(RANS) equations treating complex multi-building domains with a porosity formulation. For
modelling turbulence a one-equation eddy-viscosity model is used. The numerical results
illustrate the flow and concentration fields within the canyon and also show the influence of
the detailed geometry, such as, that of the street junction situated at the northern end of the
canyon, and that of the boulevard at the southern end.