Title: Detailed numerical modeling of local atmospheric dispersion in an idealized urban area
1Detailed numerical modeling of local atmospheric
dispersion in an idealized urban area
- M. Milliez, S. Panzarella, B. Carissimo
- CEREA
- Research and Teaching Center for Atmospheric
Environment - Chatou/Marne-la-Vallée, FRANCE
2Outline
- Objectives
- The Mercure model
- Simulation results evaluated with two
experiments - Hydraulic simulation of the MUST array
(R.W.Macdonald, C.E.Ejim, 2002) results and
comparison - MUST Mock Urban Setting Test (C.A.Biltoft et
al., 2001) results and preliminary comparison - Perspectives
3Objectives
- Investigate flows and pollution dispersion in an
urban environment analyses of flow properties
and concentration fields. - In order to
- Study the impact on population and environment on
a local scale - Describe the average building effects (in terms
of porosity, drag and turbulence) on flow and
concentration fields
4The Mercure model
- Developed by EDF and CEREA
- 3-D model adapted to atmospheric flow and
dispersion simulation - Core of the model CFD model Code_Saturne (EDF)
which can handle complex geometry and complex
physics - Unstructured grid, finite volumes
- Simulations
- Eulerian approach
- Full scale, fine resolution, complex terrain,
thermal effects - Large scale meteo. conditions taken into account
- k-? turbulence closure model
- porosity/drag option
5Hydraulic simulation of the MUST array
- Report Flow and Dispersion Data from a Hydraulic
Simulation of the MUST array, R.W. Macdonald,
C.E. Ejim,2002, University of Waterloo, Canada - Hydraulic flume with an upstream region to
simulate of a turbulent ABL flow in neutral
stability conditions. - Experiments
- 150 scale
- Array of 10x4 obstacles (200mm long, 50mm wide,
50 mm high) - Use of heat as a tracer
6Hydraulic simulation of the MUST array
- continuous release
- several locations upstream and within the array
- 3 different flow direction 0 deg, 30 deg, 45 deg
7Simulations with the Mercure model
- Mesh 900 000 elements
- Horizontal grid 0.5 m x 0.5m
- Stretched vertical grid 0.5m -gt 1.6 m
- Boundary conditions
- Upstream
- Dowstream gradients 0
8Simulations with the Mercure model
9Comparisions
Wind 0 , source upstream
10Comparisions concentration
11Comparisions concentration
12The Mock Urban Setting Test
- C.A. Biltoft, et al. Report and data, 2001.
- Near full scale experiment in the U.S. Army
Dugway Proving Ground (Utah), conducted for the
DTRA (Defense Thread Reduction Agency ) - Objectives acquire meteo. and dispersion data
set - overcome the scaling limitations of laboratories
simulations. - Neutral gas releases in a field of containers.
- Array of 10x12 obstacles (12.9 m long, 2.42 m
wide, 2.54 m high)
13The Mock Urban Setting Test
- Releases for different meteorological conditions
in several locations within the array - 63 continous releases of duration of 15 min
- Data preanalyses and statistics
14The Mock Urban Setting Test
N
Pneumatic Mast
32-m Tower (digiPIDs at 1-, 2-, 4-, 6-, 8-,10-,
16-m levels)
Line4 h1.6 m
Line5
Line3 h1.6 m
Line2 h1.6 m
Line1 h1.6 m
simulated release point Hs0.15 m
30
simulated wind
15Simulations with the Mercure model
- Mesh 800 000 hexahedral elements
- Dimensions 240 m x 233 m x 32m
- Horizontal grid lower levels
4 m
0.6 to 1m
2 m
0.3 m
4 m
16Simulations with the Mercure model
- Boundary conditions
- Upstream wind profile in a stable atmosphere
- L100
- Z00.1m
- Wind bearing 28
- u3m/s (z8m)
- Dowstream
- gradients 0
- Top
- symetry and free slip
17Simulations with the Mercure model
18Simulations with the Mercure model
Y106 m
Y146 m
19Simulations with the Mercure model
20First comparisons wind speed
Row 5
21First comparisons TKE
Row 5
22First comparisons concentration
Row 5
23First comparisons
24Conclusions
- Water flume simulations
- Satisfactory results for wind, turbulence and C
at 0 - Differences in side wall effects at 30, 45 ?
comparison not conclusive - MUST simulations
- first results encouraging comparison
- further analyses needed ( inflow profile )
25Perspectives
- More analyses / comparisons with the MUST
experiment - Future thesis work take into account heat
fluxes and radiative transfers with buildings
26Acknowledgments
- Rob Macdonald, University of Waterloo (CA)
- water flume experimental data and analysis
- Defense Threat Reduction Agency (USA)
- MUST field experiment database
- B. Carissimo was supported during his sabbatical
leave by the Comprehensive Atmospheric Modeling
Program (CAMP) at George Mason University (USA)
27Thank you
28Simulation with the Mercure model