The authors of AUSTAL2000 claim that stationary concentration distributions only occur when no external forces are acting. You confuse mass balances with force equations.
Austal2000 method has been validated questionably
The following publication is a first summary of the results of the expertise on the validity of AUSTAL2000, which was completed shortly before in 2014. The authors of the AUSTAL2000 convincingly reject all criticism of themselves. You work on behalf of the Federal Environment Agency and are not only entrusted with the development of AUSTAL2000, but also with quality assurance. However, 3D wind fields are incorrectly validated with the rigid rotation of solids. This publication shows how comparative calculations are to be carried out correctly.