Progress in Turbulence and Wind Energy IV pp 181-185 | Cite as

# A New Way to Determine the Wall Position and Friction Velocity in Wall-Bounded Turbulent Flows

## Abstract

Studies of turbulent boundary layers are often focussed on the near wall region. In experiments an accurate determination of the wall (say within 10 *μ*m) with respect to the measurement probe is not easily achieved through optical or mechanical measurements (see e.g. Ref. [1]). Also the friction velocity (*u* _{ τ }) is hard to determine with high accuracy. One possibility is to utilize the linear velocity profile (*U* ^{ + } = *y* ^{ + }) to determine one or both of the mentioned quantities, but is usually impeded by the fact that the hot-wire readings are affected by heat transfer to the wall. The motivation here is to utilize the cumulative distribution function (CDF) of the streamwise velocity in a way so that the influence of the heat transfer can be avoided and thereby obtain accurate estimates of both the wall position and friction velocity.

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## References

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