Working Group CFD Modelling

of the TRAPOS network

Members - young scientists: Matthias Ketzel (Chairperson), NERI, Roskilde, Denmark, (before: IBAL)
Petroula Louka, LTHEE/AUT, Thessaloniki, Greece, (before: ECN)
Peter Sahm,before: LTHEE/AUT, Thessaloniki, Greece
Emmanuel Guilloteau ,before: U.Karlsruhe
Associated senior scientist: Jean-Francois Sini, ECN, Nantes, France

It was decided during the TRAPOS midterm review meeting in Roskilde, January 2000, to create formal working groups for the different tasks of the network. Computational Fluid Dynamics (CFD) was defined as one of the tasks. The responsibilities of each working group are:
  • Formulation of the importance of the subject for street level pollution
  • Presentation of the TRAPOS contribution to the advancement of the subject
  • Transformation of the results into recommendations for practical models

Working Group activities

The Working Group CFD Modelling (WG CFD) started its work after the third TRAPOS meeting in Madrid (March 1999). It was decided to launch a CFD Modelling exercise within the TRAPOS network and to keep this open for participants also outside TRAPOS.


kick-off meeting March 1999 in Madrid
work meeting in June 1999 at LTHEE in Thessaloniki
TRAPOS Workshop on CFD Modelling in August 1999 in Aveiro
TRAPOS Workshop May 2000 in Nantes
work meeting July 2000 in Nantes
TRAPOS Workshop October 2000 in Zurich

Test case descriptions, preliminary results

One main criterion for the selection of the following test cases was the availability of very comprehensive field data sets or wind tunnel measurements.

Case name Case description first results
Flat Plate (2D)Pla_case.doc.
Single cavity (2D)
Multiple street canyon (2D)
Cube - CEDVAL (3D) Cub_case.doc.
Göttinger Straße (3D)Goe_case.doc
(download of all case descriptions and related example files)

Models and groups in the comparison exercise

Numerical model Group status
1. TRAPOS groups
CHENSI ECN results for 5 cases
CHENSI-2 U.Karl. / ECN results for 4 cases
MIMO LHTEE results for 5 cases
MISKAM NERI results for 4 cases
Phoenics IBAL results for 1 case
TASCflow LHTEE results for 5 cases
2. Other groups
Phoenics INERIS, Paris results for 1 case
StarCD Prof. Jicha, Bruno no results so far

In order to understand the differences among the models, a table of detailed code-description and parameterisation (Table_codes.doc) was constructed.

A general description including references for most ot the codes can be found in the Model Inventory build in the frame of a European COST project.


The aim of the present model intercomparison is :
  1. to assess and allocate the source of differences that appear when different CFD codes using the same turbulence model are applied to well defined test cases and
  2. to improve the knowledge base for model development and application
  3. to demonstrate the level of agreement that can be expected from CFD modelling in urban environment
  4. to give guidance for the procedure of the case set-up e.g. grid and inflow definitions, boudary conditions etc.
  5. to prove the CFD codes to be a powerful reliable tool for application in practical situation and for improvement of practical street pollution models.

Work status of WG CFD


P.Louka, P.Sahm, M.Ketzel, G.Theodoridis, J.-F.Sini & N.Moussiopoulos: An intercomparison of microscale models for the flow and dispersion characteristics in urban areas. Poster presented at the EUROTRAC-2-symposium, 27-31 March 2000, Garmisch-Partenkirchen, Germany. (The poster can be downloaded as MS-Publisher document as well as the exteded abstract as MS-Word file)

P. Sahm, P. Louka, M. Ketzel, E. Guilloteau, J-F. Sini: Intercomparison of numerical urban dispersion models - Part I: street canyon and single building configurations. Abstract submitted for presentation at The Third International Conference on Urban Air Quality, Loutraki, Greece, 19-23 March 2001.

M. Ketzel, P. Louka, P. Sahm, E. Guilloteau, J.-F. Sini, N. Moussiopoulos: Intercomparison of numerical urban dispersion models - Part II: street canyon in Hannover, Germany. Abstract submitted for presentation at The Third International Conference on Urban Air Quality, Loutraki, Greece, 19-23 March 2001.

P. Louka, M. Ketzel, P. Sahm, E. Guilloteau, N. Moussiopoulos, J.-F. Sini, P.G. Mestayer, R. Berkowicz: CFD Intercomparison Exercise within TRAPOS European Research Network. Abstract submitted for presentation at 7th Conference on Environmental Science & Technology, Syros, Greece, 3-6 September 2001.

M. Ketzel, P. Louka, P. Sahm, E. Guilloteau, J.-F. Sini: The use of computational fluid dynamics in modelling air quality in street canyons. Chapter 2.2 of the TRAPOS summary report in preparation.

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last modified: 07.03.2002, Matthias Ketzel