In order to produce exact specifications about air flow velocity, it is necessary to measure these specifications as precisely as possible. In practice, so-called hot-wire anemometers are used for this purpose. Owing to their small dimensions, these can measure very accurately the air flow velocities in a model and also lead to quick recognition of fluctuations (Figure 4/12).

	Fig. 4/12: Example of a horizontal flow field at 3 levels, measured in a wind tunnel by a hot-wire anemometer, Source: IHW, Karlsruhe
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