AVS. Arkitektúr verktækni skipulag - 01.12.2004, Page 40

tion present close to the observation
site. An example of a complete wind
map for a single wind direction is
presented on Figure 1. Snow-drift-
ing is estimated from wind maps
by means of theoretíc relationships
between wind and snow-drífting and
be referring experimental data on
snow-drifting under different condi-
tions.
The mapping process
The mapping process is depend-
ent on digital maps and series of
weather measurements, and a
numerical flow-solver. A 3D digital
terrain model is imported into the
simulation system, and calculations
are done for one wind direction at a
time. The number of wind directions
is variable, but if wind rose projec-
tion is demanded, all main directions
need to be simulated, either eight or
sixteen directions. Results for each
wind direction are displayed on a
raster image, describing the wind
speed distribution. Also, vectors
indicating local wind direction and
streamline analysis are available.
Raster images can be imported into
any CAD system and displayed par-
allel with the preferred data.
InlD the Wind
Dr. Skúli Þórðarson, Civil Engineer
Skúli has a C.S. degree in civil
engineering from University of
lceland and earned his PhD on
snow engineering and road plan-
ning from NTNU in Trondheim in
2002. Employed at Orion Consulting
Engineers since 2002.
Introduction
Wind climate affects daily life in
lceland substantially. Both wind
and snow-drifting causes delays for
road traffic and even road closures
in urban and suburban areas and
snow-drifting increases the snow
removal costs. Wind constrains out-
door activity in many developments
and snow-drifts may block the
entrance to houses. The layout and
design of roads and developments
affects the local influence of winds.
Of high importance, is the aspect
and location of buildings and other
structures in the landscape, and so
is the interaction of buildings and
the use of windbreaks. Information
on wind climate, such as most fre-
quent and strongest wind directions
and on snow cover and snow-drift-
ing enables designers to choose a
suitable design in terms of climate.
Wind
maps
The application
of computer
simulations and
measurements
from weather
stations now
enables wind
zone mapping.
Wind maps dis-
play the spatial
distribution of
wind speed in
the terrain and
indicate the influence of buildings
and other structures. Measurements
from a distant weather station
are projected into the observation
site, producing a wind rose, as if
a weather station was present on
the site. Results are presented on
maps, showing the wind speed
distribution on a colored scale. The
wind can be displayed on a semi-
transparent layer on top of aerial
photographs or other information
sheet. Wind roses can be trans-
ferred on to any number of observa-
tion spots on the site, and the may
be transferred over a long distance,
should there not be a weather sta-
Limitations
The wind simulatíons described here