Hence the time averaged pressure difference is

as . This can be further written as

For turbulence levels as large as , but the error in pressure measurement is , i.e. . On the other hand it can be shown that the instantaneous pressure fluctuations relate to velocity fluctuations as

Hence the pitot tube can be used for measurements of the velocity fluctuations in turbulent flows, as well, via measurement of total pressure fluctuations. As discussed in Lecture 10 Transient and Frequency Response (Example 2), pitot tubes have strong attenuation characteristics and an accurate determination of is a source of difficulty. The attenuation is quite high at higher frequencies. Hence, if the velocity spectrum does not contain high frequency components, the measurement of velocity fluctuations can still be carried out.