Time of Scour at Elliptical Guide Banks
2nd International Workshop on Hydraulic Structures (IWHS-2015) 2015
Boriss Gjunsburgs, Oskars Lauva

At steady flow conditions the depth of scour is rapidly developing at the initial stage and later gradually reducing; scour evaluation stops at equilibrium depth in equilibrium time. Analysis of the literature shows that there are no methods or formulas to calculate equilibrium time of scour near elliptical guide banks. In this paper we are going to present the method for calculation equilibrium time near elliptical guide banks in uniform sand and at clear water conditions. The differential equation of the bed sediment movement in clear water was used and the method for computing equilibrium time of scour was elaborated. New hydraulic criterion is proposed to find equilibrium time of scour near elliptical guide banks. According to the method presented the equilibrium time of scour is depending on: Froude number, contraction rate of the flow, bed layering, grain size diameter, local flow velocity, and ratio of local velocity to critical one, and is changing with depth of scour. The test results of scour evaluation in time with duration of 7 hours were prolonged till the equilibrium stage of scour (Gjunsburgs et al., 2006) and compared with equilibrium time of scour calculated by the method presented, and they were in good agreement.


Atslēgas vārdi
: local scour, equilibrium time, contraction rate of the flow

Gjunsburgs, B., Lauva, O. Time of Scour at Elliptical Guide Banks. No: 2nd International Workshop on Hydraulic Structures (IWHS-2015), Portugāle, Coimbra, 7.-9. maijs, 2015. Coimbra: University of Coimbra, 2015, 97.-104.lpp. ISBN 978-989-98435-9-2.

Publikācijas valoda
English (en)
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