Velocity and Sediment‐Concentration Profiles in River Flows

Karim, M. Fazle; Kennedy, John F.

doi:10.1061/(asce)0733-9429(1987)113:2(159)

Cited by 25 publications

(10 citation statements)

References 10 publications

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“…Itakura and Kishi [1980]applied the Monin‐Obukhov theory for the length scale in sediment‐laden flow and found a linear wake profile, which made their approach conceptually similar to Coleman 's [1981, 1984, 1986]. As an alternative to the log‐wake law, a power law velocity profile for sediment suspension was considered by Karim and Kennedy [1987] and Woo et al [1988]. Adopting the entropy concept Chiu et al [2000] proposed yet another expression for the velocity profile.…”

Section: Introductionmentioning

confidence: 99%

Is the von Kármán constant affected by sediment suspension?

Castro-Orgaz¹,

Giráldez²,

Mateos³

et al. 2012

J. Geophys. Res.

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[1] Is the von Kármán constant affected by sediment suspension? The presence of suspended sediment in channels and fluvial streams has been known for decades to affect turbulence transfer mechanism in sediment-laden flows, and, therefore, the transport and fate of sediments that determine the bathymetry of natural water courses. This study explores the density stratification effects on the turbulent velocity profile and its impact on the transport of sediment. There is as yet no consensus in the scientific community on the effect of sediment suspension on the von Kármán parameter, k. Two different theories based on the empirical log-wake velocity profile are currently under debate: One supports a universal value of k = 0.41 and a strength of the wake, P, that is affected by suspended sediment. The other suggests that both k and P could vary with suspended sediment. These different theories result in a conceptual problem regarding the effect of suspended sediment on k, which has divided the research area. In this study, a new mixing length theory is proposed to describe theoretically the turbulent velocity profile. The analytical approach provides added insight defining k as a turbulent parameter which varies with the distance to the bed in sediment-laden flows. The theory is compared with previous experimental data and simulations using a k-ɛ turbulence closure to the Reynolds averaged Navier Stokes equations model. The mixing length model indicates that the two contradictory theories incorporate the stratified flow effect into a different component of the log-wake law. The results of this work show that the log-wake fit with a reduced k is the physically coherent approximation.

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Section: Introductionmentioning

confidence: 99%

Is the von Kármán constant affected by sediment suspension?

Castro-Orgaz¹,

Giráldez²,

Mateos³

et al. 2012

J. Geophys. Res.

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show abstract

“…Consequently, mean water column velocity in wadeable streams may be a reasonable surrogate variable for the hydraulic variables (in this case nose velocity) that determine fish habitat selection. Additionally, velocity profiles most nearly follow the theoretical logarithmic ideal in runs and pools of simple channels having sand or gravel substrate (Walker 1988;Karim and Kennedy 1987;Chiu 1989), further strengthening the case that mean velocity and nose velocity for salmonids should be highly correlated in streams of the size range described in early IFIM studies. For deeper rivers, rivers with large substrate, or for smaller fish (in which nose velocities may be closer to the bottom), the correlation between mean water velocity and hydraulic conditions in the immediate vicinity of the fish should decrease, and mean velocity may become a less useful hydraulic variable to describe habitat selection.…”

mentioning

confidence: 53%

Instream Flow Incremental Methodology: A Synopsis with Recommendations for Use and Suggestions for Future Research

Nestler¹

1993

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“…1. The power-law velocity distribution for flow in an open channel can be stated as follows (Sarma et al 1983 where n = a parameter determined by the frierional resistance at the bed that usually is in the range of 6-7 (Karim and Kennedy 1987). In practice, n is not known and its value is often estimated from sources as stated previously.…”

Section: Comparison Of Velocity Profile Methodsmentioning

confidence: 99%

Solution of Three‐Constraint Entropy‐Based Velocity Distribution

1991

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A two-dimensional velocity profile based upon the principle of maximum entropy (POME) for wide open channel flows is presented. The derivation is based on the conservation of mass and momentum. The resulting profile involves three parameters that are determined from observations of mean velocity and the velocity at the water surface. The velocity profile is verified using field data in a river with a live bed. A comparison with three existing methods shows that the profile presented is the most accurate of the three, especially near the bed.

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Velocity and Sediment‐Concentration Profiles in River Flows

Cited by 25 publications

References 10 publications

Is the von Kármán constant affected by sediment suspension?

Is the von Kármán constant affected by sediment suspension?

Instream Flow Incremental Methodology: A Synopsis with Recommendations for Use and Suggestions for Future Research

Solution of Three‐Constraint Entropy‐Based Velocity Distribution

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