## Indicators

• Similars in SciELO

## On-line version ISSN 2007-4026Print version ISSN 2007-3925

#### Abstract

MENDOZA-GONZALEZ, Ángel  and  AGUILAR-CHAVEZ, Ariosto. Determination of shear velocity in a mild-sloping open channel flow. Ing. agric. biosist. [online]. 2018, vol.10, n.1, pp.3-12.  Epub Aug 24, 2020. ISSN 2007-4026.  https://doi.org/10.5154/r.inagbi.2017.01.002.

Objective:

To present a methodology that allows experimentally determining shear velocity, considering the log-law as a model of velocity distribution in the outer region of turbulent flow.

Mathodology:

The experimental study was carried out in a rectangular-shaped, variably-sloped channel with a 0.245-m-wide base and 5 m long. Flow velocity was measured with an Acoustic Doppler Velocimeter (ADV), and the measurement area was 12 mm. Shear velocity was determined by the instantaneous velocity equation (${u}_{i,j}$).

Results:

The log-law model had a good statistical fit with the shear velocity estimated from the experimental data.

Study limitations:

The experimental tests were conducted only in subcritical regime with low aspect ratios. In addition, in all tests, the measurement of instantaneous velocities was carried out only in a 12-mm profile, as close as possible to the wall.

Originality:

The model to calculate the shear velocity is presented explicitly, and the statistical

approach employed supports the use of the median as an estimator of the shear velocity.

Conclusions:

The presented methodology shows low uncertainty in the estimation of shear velocity. The Anderson-Darling test showed that the results do not follow a normal distribution, so the median is the statistical parameter to define the shear velocity value.

Keywords : shear stress; acoustic Doppler velocimetry; log-law.

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