Experimental Study on the Near-Bed Flow Characteristics of Alluvial Channel with Seepage

This paper aims to analyze the turbulent structure of flows over beds undergoing downward seepage under clear-water conditions. Laboratory experiments in this regard were carried out in a straight rectangular channel that was 17.20 m long and 1.00 m wide. A sandy bed with median grain size d50 = 0.5...

Full description

Saved in:

Bibliographic Details
Published in:	Applied sciences 2021-10, Vol.11 (20), p.9619
Main Authors:	Sharma, Anurag, Kumar, Bimlesh, Oliveto, Giuseppe
Format:	Article
Language:	eng
Subjects:	Acoustics Alluvial channels clear-water regime Experiments Flow Flow characteristics Flow velocity Grain size higher-order moments of velocity fluctuations Influence Kurtosis Laboratories Morphology near-bed turbulence characteristics Reynolds number River beds Rivers Sediment transport Seepage seepage flow Shear stress Turbulence intensity
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	This paper aims to analyze the turbulent structure of flows over beds undergoing downward seepage under clear-water conditions. Laboratory experiments in this regard were carried out in a straight rectangular channel that was 17.20 m long and 1.00 m wide. A sandy bed with median grain size d50 = 0.50 mm and sediment gradation σg = 1.65 (i.e., slightly non-uniform sediment) was used for the channel bed. The 3D instantaneous velocities of water were measured with an Acoustic Doppler Velocimeter (ADV) at the working test section. In the vicinity of the bed surface with seepage, measurements revealed that the flow longitudinal velocities (i.e., velocities in x direction) were higher than those in the case of a bed without seepage. Moreover, the variations inthe Reynolds shear stresses increased for the bed with seepage, indicating a higher exchange of flow energy towards the boundary and vice versa. Therefore, it was found that seepage processes influence the turbulence intensity, with a prominent magnitude in the streamwise and vertical directions. The paper also focuses on the third-order moment (skewness) and the kurtosis of velocity fluctuations and the governance of sweep events within the near-bed flow in cases where seepage was observed.
ISSN:	2076-3417 2076-3417