Calculation of the stack height according to TA Luft 1986/2002
with regard to rugged terrain according to VDI 3781 Part 2
Translated extract of VDI 3781 Part 2 published by
Dispersion of Pollutants in the Atmosphere
Stack heights with regard to rugged terrain
The known calculation procedures of the minimum stack height according
to  are valid for flat terrain only. The purpose of the present Guideline
VDI 3781 Part 2 is to extend the calculation procedure to rugged terrain.
Therefore it replaces the draft VDI 2289 Part 3, edition 10.69.
To determine the correction, the geometry of the terrain and the
conformity to the Science of flow are to be considered.
The theory based on this Guideline is fully described in the work of
In derivation of this theory the following is assumed:
- easy to categorize long drawn-out elevation or depression,
- flat stationary Zone of flow vertically to the elevation or
- Streamline motion in greater distance to the ground,
- Determination of the wind velocity in the layers near the ground of
the relating streamline motion by formal transfer of the case of absent ground
- Use of a simplified fixed form of the diffusion equation according to
Fick with constant coefficients.
These conditions, according to the current state of knowledge, are
necessary for a survey of the problem dealt with in this Guideline. However,
according to terrain and climatic conditions of location, in reality the
conditions serve its purposes roughly. Considering the climatic conditions,
smaller stack heights may result than those calculated according to this
In cases where this Guideline is not to be used, because of the
conditions mentioned in the theory, an expert for dispersion should be