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Interface MISKAM wind and turbulence fields for AUSTAL2000

 

WinMISKAM
... MISKAM © for Windows

© Dr. J. Eichhorn, Working Group Urban Climatology, Institute for Atmospheric Physics,
University of Mainz, D-55099 Mainz, Germany


 

 

WinMISKAM-supplementary module

"Interface MISKAM wind and turbulence fields for AUSTAL2000"

 

 

AUSTAL2000, the official dispersion program for the "Technical Instruction Clean Air" (TA Luft), allows the use of externally calculated wind- and turbulence fields. A need for the applications of externally calculated wind fields is given if the flow field is influenced by buildings. These fields have to be provided to AUSTAL2000 in a certain format.

Using the supplementary module "Interface MISKAM wind and turbulence fields for AUSTAL2000" it is possible, to convert wind fields, calculated by MISKAM, and to file them in a wind field library. The interface works project oriented and allows as well the calculation and conversion of the wind- and turbulence fields as the conversion of already existing wind- and turbulence fields and their filing in a wind field library.

The supplementary module is directly integrated into the basic version of WinMISKAM and can be started directly via the menue. With the help of a "wizard" the user is guided in 5 steps to the calculation of the MISKAM-windfields and the subsequent conversion of the results into the AUSTAL2000 format. To be able to later reproduce the calculation and the conversion, all necessary data and parameters are saved in a project file.

Is is also possible to convert the velocity fluctuation fields and the exchange coefficients.

As the physics of the flow and dispersion models of MISKAM and AUSTAL2000 differ, there are restrictions in the use of MISKAM-windfields for calculations using AUSTAL2000:

  • The flow module within MISKAM does not use the exact boundary layer profiles, demanded in TA Luft. Additionally there is no deviation of the wind direction with the height above ground
  • AUSTAL2000 only allows an equally spaced grid. That means the wind fields, calculated with MISKAM also need to have an equidistant grid within the inner investigation area
  • MISKAM-windfields can not be determined for topographically influenced terrain, MISKAM is not validated for these cases. Therefore only the case of buildings in flat terrain is supported by the interface.
  • Not all possible atmospheric stabilities can be handled by MISKAM. Only the neutral stability case is validated. For stable stability the results are reasonable but for unstable classes the physics of MISKAM are not suitable. Therefore unstable classes are not supported by the interface.
  • Calculations with nested grids presently are not supported by the interface, as it would not reduce the computing time significantly. But in principle, it would be possible to use nested grids from MISKAM in WinAUSTAL2000.

Manual "Interface MISKAM-windfields for AUSTAL2000", pfd-file, 0,26 MB) (in German only)