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Methods of Information Acquisition
for Planning (Nature measurements, Wind tunnels, Modelling) |
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4.2.5 Example
Use – Ventilation Scenario (Expansion of an Earth Dump)
4.2.5.3 Relevant Results for Planning In the context of the study, the changes in the ground wind field resulting from the various expansion plans were simulated in a wind tunnel. Wind velocity and turbulence were measured for 8 wind directions at 50 points in the model. As an example, the situation for the wind direction northwest is depicted in Figure 4/27. It shows the distribution of average wind velocities, while Figure 4/28 shows the relative change versus existing conditions. Degradations in wind velocity of more than 10% are shown with a border. Altogether it was determined that the effects on the ground wind field from the existing earth dump reach to a leeward distance of ca. 600 m. The planned expansions modify the ground wind field in two respects. The average wind velocity in the lee of the expansion is reduced by about 10% (in isolated areas up to 20%) in comparison with the existing state. Decreases in velocity also appear in some locations, however, owing to canalization and altitude effects. The turbulence of air flow increases in the lee and laterally of the planned expansion. Only in isolated areas was there a decrease in turbulence of about 10%. Changes of less than 10% in wind velocity and turbulence at a height of 10 m were classified as irrelevant (LOHMEYER and PLATE, 1986). From this the result it was possible to determine that the planned expansion should not result in a negative change in the propagation of exhaust gases near the ground in relation to both the neighboring commercial district and bordering residential areas. The analysis of the wind field up to an altitude of 100 m above ground in the lee of the planned expansion revealed that only an insignificant change in the wind field would result. The large-scale ventilation of the area is thus undisturbed by the planning. |
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