detailed numerical modeling of local atmospheric dispersion in an idealized urban area

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Detailed numerical modeling of local atmospheric dispersion in

an idealized urban area

M. Milliez, S. Panzarella, B. CarissimoCEREA

Research and Teaching Center for Atmospheric Environment

Chatou/Marne-la-Vallée, FRANCE

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Outline 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

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Objectives 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

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

The 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

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Hydraulic 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: 1:50 scale Array of 10x4 obstacles (200mm long, 50mm wide, 50

mm high) Use of heat as a tracer

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Hydraulic simulation of the MUST array continuous release:

several locations upstream and within the array 3 different flow direction: 0 deg, 30 deg, 45 deg

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Simulations with the Mercure model Mesh: ~900 000 elements Horizontal grid = 0.5 m x

0.5m Stretched vertical grid =

0.5m -> 1.6 m

Boundary conditions: Upstream :

Dowstream: gradients = 0

2*

3*

*( ) ln( )

0

u zu z

z

uk

C

u

z

z0=0.3m

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Simulations with the Mercure model

0 ° 30 °

45 °

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

ComparisionsWind 0 °, source upstream

U TKE

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Comparisions: concentration

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Comparisions: concentration

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

The 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)

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

The 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

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

The Mock Urban Setting TestNPneumatic Mast

simulated wind

30°

Line1 h=1.6 m

Line2 h=1.6 m

32-m Tower(digiPIDs at 1-, 2-, 4-, 6-, 8-,10-, 16-m levels)

Line5

Line4 h=1.6 m

Line3 h=1.6 m

simulated release point:

Hs=0.15 m

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Simulations with the Mercure model

Horizontal grid : lower levels

Stretched vertical grid~4 m

~2 m

0.6 to 1m

~0.3 m

~4 m

Mesh: ~800 000 hexahedral elements Dimensions: 240 m x 233 m x 32m

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Simulations with the Mercure model Boundary conditions:

Upstream :wind profile in a stable atmosphere

L=100 Z0=0.1m

Wind bearing: 28 ° u~3m/s (z=8m)

Dowstream: gradients = 0 Top : symetry and free slip

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Simulations with the Mercure model

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Simulations with the Mercure model

Y=86 mY=106 mY=146 m

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Simulations with the Mercure model

Y=86 m

Y=106 m

Y=146 m

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

First comparisons: wind speed

1

3

2

Row 5

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

First comparisons: TKE

1

3

2

Row 5

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

First comparisons: concentration

1

3

2

Row 5

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

First comparisons

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Conclusions 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 …)

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Perspectives

More analyses / comparisons with the MUST experiment

Future thesis work = take into account heat fluxes and radiative transfers with buildings

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Acknowledgments 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)

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Thank you

Maya Milliez

NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004

Simulation with the Mercure model