The estimation of velocity proﬁle in turbulent open channels is a difﬁcult task due to the signiﬁcant effects of the secondary ﬂow. The present paper investigates the mechanism of the velocity-dip phenomenon, whereby the location of the maximum velocity appears to be below the free surface. Previous studies conducted in straight channels relate the mechanism of the velocity-dip phenomenon to secondary ﬂow induced by anisotropy of turbulence. This work focuses on high-curved channels where the secondary motion, which is also induced by the channel’s curvature, evolves along the bend. The width-to-depth ratio, B/h, is one of the most important parameters that are affecting the secondary motion entity. In particular, the present study aims to investigatetheevolutionofthevelocity-dipalongthebendfortwovaluesofthewidth-to-depthratio andtheapplicabilityoftheentropicmodelforthedip-phenomenonestimation. Theresultsshowthat the velocity-dip is more accentuated for low values of the width-to-depth ratio, where the secondary motion plays a fundamental role in the distribution of the downstream ﬂow velocity, although the velocity-dip is also present when the aspect ratio is higher than 10. Furthermore, the velocity proﬁles that were estimated by applying the entropic model are in good agreement with the measured ones, especially for B/h < 10.
|Numero di pagine||10|
|Stato di pubblicazione||Published - 2018|
All Science Journal Classification (ASJC) codes
- Geography, Planning and Development
- Aquatic Science
- Water Science and Technology