NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004 Detailed 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

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: ~ elements Horizontal grid = 0.5 m x 0.5m Stretched vertical grid = 0.5m -> 1.6 m Boundary conditions:  Upstream :  Dowstream: gradients = 0 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 Comparisions Wind 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, 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 Test N Pneumatic 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: ~ 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 Row 5

Maya Milliez NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004 First comparisons: TKE Row 5

Maya Milliez NATO ADVANCED STUDY INSTITUTE, Kyiv, May 2004 First comparisons: concentration 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)Comprehensive Atmospheric Modeling Program

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