scholarly journals A Unified Approach to Bed Load Transport Description Over a Wide Range of Flow Conditions via the Use of Conditional Data Treatment

2018 ◽  
Vol 54 (5) ◽  
pp. 3490-3509 ◽  
Author(s):  
WuRong Shih ◽  
Panayiotis Diplas
Keyword(s):  
Bed Load ◽  
Flow Conditions ◽  
Unified Approach ◽  
Data Treatment ◽  
Wide Range ◽  
Load Transport ◽  
Bed Load Transport

scholarly journals INFLUENCE OF GRAIN SIZE ON LITTORAL DRIFT

1970 ◽  
Vol 1 (12) ◽  
pp. 56 ◽  
Author(s):  
Jose Castanho
Keyword(s):  
Grain Size ◽  
Shear Stress ◽  
Bed Load ◽  
Flow Conditions ◽  
Littoral Drift ◽  
Flow Shear ◽  
Load Transport ◽  
Bed Load Transport ◽  
Flow Shear Stress ◽  
Load Discharge

Influence of grain size in sediment transport depends on flow conditions For bed load transport a maximum probably exists for load discharge as a function of gram size The important parameter seems to be the ratio To/T between the threshold shear stress and the flow shear stress.

scholarly journals Conditions at interfaces of layered flow with intense bed load transport

2019 ◽  
Vol 213 ◽  
pp. 02056
Author(s):  
Václav Matoušek ◽  
Jan Krupička ◽  
Tomáš Picek ◽  
Štěpán Zrostlík
Keyword(s):  
Kinetic Theory ◽  
Transport Model ◽  
Bed Load ◽  
Flow Conditions ◽  
Laser Stripe ◽  
Load Transport ◽  
Uppermost Layer ◽  
Bed Load Transport ◽  
Layered Flow ◽  
The Individual

Intense bed load transport in open channel flow is typically associated with a layered structure of the flow, in which individual layers exhibit different mechanisms of support and friction of transported sediment grains. In the lowermost layer adjacent to the channel bed, the grains slide over each other and maintain virtually permanent contact. In the uppermost layer below the water surface, typically no grains are transported. In the central layer, the grains collide with each other producing typical distributions of granular concentration and velocity across the collisional layer. Mathematical models describing the layered flow with intense bed load (as models based on kinetic theory of granular flows) consider flow conditions at interfaces of the individual layers in their flow predictions. Usually, experimental verification of interfacial predictions is lacking. We exploit results of our new experiments with plastic cylindrical sediment to identify a variation of the conditions at the interfaces (local interfacial granular concentrations and velocities) with varying flow discharge, depth and slope in a laboratory tilting flume. The experimental results include local granular concentration using an improved laser stripe method. The experiments are compared with predictions using our kinetic-theory based transport model with the aim to evaluate a match for experimentally-determined and model-predicted interfacial parameters.

scholarly journals A bed load transport equation based on the spatial distribution of shear stress – Oak Creek revisit

2020 ◽  
Author(s):  
Angel Monsalve ◽  
Catalina Segura ◽  
Nicole Hucke ◽  
Scott Katz
Keyword(s):  
Shear Stress ◽  
Flow Field ◽  
Transport Equation ◽  
Bed Load ◽  
Bankfull Discharge ◽  
Wide Range ◽  
Average Shear ◽  
Load Transport ◽  
Two Dimensional Flow ◽  
Bed Load Transport

Abstract. Bed load transport formulations for gravel bed-rivers are often based on reach-averaged shear stress values. However, the complexity of the flow field in these systems results in wide distributions of shear stress, whose effects on bed load transport are not well captured by the frequently used bed load transport equations, leading to inaccurate estimates of sediment transport. Here, we modified a subsurface-based bed load transport equation to include the complete distributions of shear stress generated by a given flow within a reach. The equation was calibrated and verified using bed load data measured at Oak Creek, OR. The spatially variable flow field characterization was obtained using a two-dimensional flow model calibrated over a wide range of flows between 0.1 and 1.0 of bankfull discharge. The shape of the distributions of shear stress was remarkably similar across different discharge levels which allowed it to be parameterized in terms of discharge using a Gamma function. When discharge is high enough to mobilize the pavement layer (1.0 m3/s in Oak Creek), the proposed transport equation had a similar performance to the original formulation based on reach-averaged shear stress values. In addition, the proposed equation predicts bed load transport rates for lower flows when the pavement layer is still present because it accounts for bed load transport occurring in a small fraction of the channel bed that experience high values of shear stress. This is an improvement over the original equation, which fails to estimate this bed load flux by relying solely on reach-average shear stress values.

scholarly journals A bed load transport equation based on the spatial distribution of shear stress – Oak Creek revisited

2020 ◽  
Vol 8 (3) ◽  
pp. 825-839
Author(s):  
Angel Monsalve ◽  
Catalina Segura ◽  
Nicole Hucke ◽  
Scott Katz
Keyword(s):  
Shear Stress ◽  
Flow Field ◽  
Transport Equation ◽  
Bed Load ◽  
Bankfull Discharge ◽  
Wide Range ◽  
Average Shear ◽  
Load Transport ◽  
Two Dimensional Flow ◽  
Bed Load Transport

Abstract. Bed load transport formulations for gravel-bed rivers are often based on reach-averaged shear stress values. However, the complexity of the flow field in these systems results in wide distributions of shear stress, whose effects on bed load transport are not well captured by the frequently used equations, leading to inaccurate estimates of sediment transport. Here, we modified a subsurface-based bed load transport equation to include the complete distributions of shear stress generated by a given flow within a reach. The equation was calibrated and verified using bed load data measured at Oak Creek, OR. The spatially variable flow field characterization was obtained using a two-dimensional flow model calibrated over a wide range of flows between 0.1 and 1.0 of bankfull discharge. The shape of the distributions of shear stress was remarkably similar across different discharge levels, which allowed it to be parameterized in terms of discharge using a gamma function. When discharge is high enough to mobilize the pavement layer (1.0 m3 s−1 in Oak Creek), the proposed transport equation had a similar performance to the original formulation based on reach-averaged shear stress values. In addition, the proposed equation predicts bed load transport rates for lower flows when the pavement layer is still present because it accounts for bed load transport occurring in a small fraction of the channel bed that experiences high values of shear stress. This is an improvement over the original equation, which fails to estimate this bed load flux by relying solely on reach-average shear stress values.

NUMERICAL MODEL TO SIMULATE THE EROSION ON THE SLOPE DUE TO OVERTOPPING

2010 ◽  
Vol 13 (3) ◽  
pp. 78-87
Author(s):  
Hoai Cong Huynh
Keyword(s):  
Numerical Model ◽  
Flow Model ◽  
Bed Load ◽  
Experiment Data ◽  
Step Method ◽  
Morphological Model ◽  
Load Transport ◽  
Bed Load Transport ◽  
The Finite Difference Method ◽  
Good Agreement

The numerical model is developed consisting of a 1D flow model and the morphological model to simulate the erosion due to the water overtopping. The step method is applied to solve the water surface on the slope and the finite difference method of the modified Lax Scheme is applied for bed change equation. The Meyer-Peter and Muller formulae is used to determine the bed load transport rate. The model is calibrated and verified based on the data in experiment. It is found that the computed results and experiment data are good agreement.

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