scholarly journals PRACTICAL SCALING OF COASTAL MODELS

1974 ◽  
Vol 1 (14) ◽  
pp. 121
Author(s):  
J.W. Kamphuis
Keyword(s):  
Sediment Transport ◽  
Theoretical Approach ◽  
Wave Motion ◽  
Scale Effects ◽  
Fixed Bed ◽  
Mobile Bed ◽  
Long Wave ◽  
Motion Time ◽  
Practical Design ◽  
Basic Scale

In this paper the practical design of coastal mobile bed models is considered. The semi-theoretical approach expressed by the author in earlier publications (9,10,11,12) is extended and used to classify and design coastal models. Fixed bed coastal models are discussed first to form a basis for the argument. Subsequently, mobile bed models are classified according to criteria of dynamic similarity satisfied in their design and scale effects present in their operation. Basic scale laws are next derived for all classifications of coastal models. This is done for both inshore and offshore models, the distinction being brought about by adjusting the velocity scales for unidirectional (and long wave) motion. Time and sediment transport scales are next derived and some well known models are compared. The presence of bedform and model distortion is also treated. The work is compared with that of other authors.

scholarly journals Rill flow resistance law under sediment transport

2021 ◽  
Author(s):  
Costanza Di Stefano ◽  
Alessio Nicosia ◽  
Vincenzo Palmeri ◽  
Vincenzo Pampalone ◽  
Vito Ferro
Keyword(s):  
Sediment Transport ◽  
Flow Velocity ◽  
Friction Factor ◽  
Flow Resistance ◽  
Fixed Bed ◽  
Accurate Estimate ◽  
Mean Flow ◽  
Mobile Bed ◽  
Resistance Equation ◽  
Rill Flow

Abstract Purpose In this paper, a deduced flow resistance equation for open-channel flow was tested using measurements carried out in mobile bed rills with sediment-laden flows and fixed bed rills. The main aims were to (i) assess the effect of sediment transport on rill flow resistance, and (ii) test the slope-flow velocity relationship in fixed bed rills. Methods The following analysis was developed: (i) a relationship between the Γ function of the velocity profile, the rill slope and the Froude number was calibrated using measurements carried out on fixed bed rills; (ii) the component of Darcy-Weisbach friction factor due to sediment transport was deduced using the corresponding measurements carried out on mobile bed rills (grain resistance and sediment transport) and the values estimated by flow resistance equation (grain resistance) for fixed bed rills in the same slope and hydraulic conditions; (iii) the Γ function relationship was calibrated using measurements carried out on mobile bed rills and the data of Jiang et al. (2018). Results This analysis demonstrated that the effect of sediment transport on rill flow resistance law is appreciable only for 7.7% of the examined cases and that the theoretical approach allows for an accurate estimate of the Darcy-Weisbach friction factor. Furthermore, for both fixed and mobile beds, the mean flow velocity was independent of channel slope, as suggested by Govers (1992) for mobile bed rills. Conclusions The investigation highlighted that the effect of sediment transport on rill flow resistance is almost negligible for most of the cases and that the experimental procedure for fixing rills caused the unexpected slope independence of flow velocity.

Mathematical modelling of riverbed dynamics – a Canadian case study

1991 ◽  
Vol 18 (5) ◽  
pp. 772-780 ◽  
Author(s):  
B. Morse ◽  
R. D. Townsend ◽  
M. Sydor
Keyword(s):  
Mathematical Model ◽  
Sediment Transport ◽  
Model Simulation ◽  
Fixed Bed ◽  
Channel Network ◽  
Bed Elevation ◽  
Mobile Bed ◽  
Cumulative Change ◽  
Degradation Pattern ◽  
River Training

A new mobile-bed mathematical model for simulating sediment transport in river networks under unsteady flow conditions is presented. The new model, ONE-D-SED, is an extended version of the extensively validated fixed-bed, one-dimensional hydrodynamic model ONE-D. This paper reports the results of an application of ONE-D-SED to simulate bed profile development along a 43-km-long tidal channel network of the Lower Fraser River in British Columbia. The sand-bed study reach has been undergoing degradation caused by navigational dredging and river training works in lower channel reaches and by borrow dredging within the study reach itself, ONE-D-SED was used to simulate bed degradation in the study reach during the 1979–1984 period. The simulated annual change in bed elevation at the downstream end of the study reach showed good agreement with that observed during 1968, the data year used to calibrate the model. The predicted cumulative change in bed profile from 1979 to 1984 also compared favourably with the overall degradation pattern observed during that same period. Key words: mathematical model, simulation, sediment transport, river network, finite difference, model validation.

scholarly journals Fixed-Bed and Mobile-Bed Resistance of Channels with Steep Gradients in Mountainous Areas

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 681
Author(s):  
Ji Hou ◽  
Chunze Zhang ◽  
Dan Wang ◽  
Feng Li ◽  
Zijian Yu ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Fixed Bed ◽  
Load Resistance ◽  
Mountain Streams ◽  
Bed Load ◽  
Mountainous Areas ◽  
Alluvial Rivers ◽  
Mobile Bed ◽  
Load Movement ◽  
Basic Expression

Flood discharge and sediment transport are closely linked to channel resistance in steep mountain streams. Previous research has mainly focused on the resistance of fixed-bed channels with steep gradients and mobile-bed channels in alluvial rivers. The present study performs an experiment and establishes a calculation method for the fixed-bed resistance of mountain channels. The basic expression of the mobile-bed resistance of steep mountain channels is derived by determining the controlling factors of the bed load movement on the riverbed resistance. The proposed formula can accurately predict the variation of the bed load resistance. The results of the present research improve the understanding of fluid dynamics and sediment transport in steep mountain channels.

Sediment transport over fixed deposited beds in sewers - An appraisal of existing models

1997 ◽  
Vol 36 (8-9) ◽  
pp. 123-128 ◽  
Author(s):  
C. Nalluri ◽  
A. K. El-Zaemey ◽  
H. L. Chan
Keyword(s):  
Sediment Transport ◽  
Fixed Bed ◽  
Transport Equations ◽  
Design Criterion ◽  
Pipe Diameter ◽  
Transport Velocity

An appraisal of the existing sediment transport equations was made using May et al (1989) and Ackers (1991) sediment transport equations for the limit of deposition design criterion and with a deposit depth of 1% of the pipe diameter allowed in the sewers. The applicability of those equations for sewers with larger fixed bed deposit depth was assessed, the equations generally over-estimated the transport velocity. Modifications were made to enable the equations to apply to sewers with large fixed bed deposits present.

Closure to “Sediment Transport in Smooth Fixed Bed Channels”

1977 ◽  
Vol 103 (7) ◽  
pp. 805-806
Author(s):  
Pavel Novak ◽  
Chandramouli Nalluri
Keyword(s):  
Sediment Transport ◽  
Fixed Bed

scholarly journals Analysis of sediment particle velocity in wave motion based on wave flume experiments

2012 ◽  
Vol 34 (2) ◽  
pp. 41-50
Author(s):  
Adam Krupiński
Keyword(s):  
Sediment Transport ◽  
Wave Motion ◽  
Steady Motion ◽  
Field Analysis ◽  
Flume Experiments ◽  
Mean Velocity ◽  
Single Wave ◽  
Wave Flume ◽  
Dynamic Velocity ◽  
Bed Material

Abstract The experiment described was one of the elements of research into sediment transport conducted by the Division of Geotechnics of West-Pomeranian University of Technology. The experimental analyses were performed within the framework of the project “Building a knowledge transfer network on the directions and perspectives of developing wave laboratory and in situ research using innovative research equipment” launched by the Institute of Hydroengineering of the Polish Academy of Sciences in Gdańsk. The objective of the experiment was to determine relations between sediment transport and wave motion parameters and then use the obtained results to modify formulas defining sediment transport in rivers, like Ackers-White formula, by introducing basic parameters of wave motion as the force generating bed material transport. The article presents selected results of the experiment concerning sediment velocity field analysis conducted for different parameters of wave motion. The velocity vectors of particles suspended in water were measured with a Particle Image Velocimetry (PIV) apparatus registering suspended particles in a measurement flume by producing a series of laser pulses and analysing their displacement with a high-sensitivity camera connected to a computer. The article presents velocity fields of suspended bed material particles measured in the longitudinal section of the wave flume and their comparison with water velocity profiles calculated for the definite wave parameters. The results presented will be used in further research for relating parameters essential for the description of monochromatic wave motion to basic sediment transport parameters and „transforming” mean velocity and dynamic velocity in steady motion to mean wave front velocity and dynamic velocity in wave motion for a single wave.

A comparison of one-dimensional methods for estimating discharge capacity of straight compound channels

2004 ◽  
Vol 31 (4) ◽  
pp. 619-631 ◽  
Author(s):  
Galip Seckin
Keyword(s):  
Discharge Capacity ◽  
Single Channel ◽  
Scale Effects ◽  
Compound Channels ◽  
One Dimensional ◽  
Mobile Bed ◽  
Series Of Experiments ◽  
And Performance ◽  
Discharge Estimation ◽  
Fixed Boundaries

A series of experiments was carried out in a two-stage flume having a smooth main channel and smooth or rough floodplains to investigate the reliability and performance of four different one-dimensional methods for computing the discharge capacity of compound channels, namely, the single-channel method (SCM), the divided-channel method (DCM), the exchange discharge method (EDM), and the Ackers method (AM). Additional data from fixed- and mobile-bed compound laboratory channels with smooth and roughened floodplains and of a prototype compound river channel were also used in the computations. The boundary roughness and scale effects associated with the performance of the four methods are also examined. The results show that the EDM and the AM are able to simulate the measured discharge values more accurately than those of the traditional methods, namely, the DCM and the SCM. Although the error in discharge estimation produced by both the AM and the EDM was generally lower than 10% for both smooth and fixed boundaries, it increased up to 20% for mobile boundaries. Overall, the average relative error in discharge estimations using the AM and the EDM was about 5.4% and 7.1%, respectively, with a standard deviation of 6.7% and 6.8%, respectively. Key words: compound channel flow, stage-discharge relationship, one-dimensional methods.

scholarly journals Size Effects on Surface Elastic Waves in a Semi-Infinite Medium with Atomic Defect Generation

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
F. Mirzade
Keyword(s):  
Surface Waves ◽  
Wave Motion ◽  
Scale Effects ◽  
Critical Value ◽  
Elastic Half Space ◽  
Small Scale ◽  
Surface Wave Propagation ◽  
Atom Interaction ◽  
Basic Equations ◽  
Phase Velocity And Attenuation

The paper investigates small-scale effects on the Rayleigh-type surface wave propagation in an isotopic elastic half-space upon laser irradiation. Based on Eringen’s theory of nonlocal continuum mechanics, the basic equations of wave motion and laser-induced atomic defect dynamics are derived. Dispersion equation that governs the Rayleigh surface waves in the considered medium is derived and analyzed. Explicit expressions for phase velocity and attenuation (amplification) coefficients which characterize surface waves are obtained. It is shown that if the generation rate is above the critical value, due to concentration-elastic instability, nanometer sized ordered concentration-strain structures on the surface or volume of solids arise. The spatial scale of these structures is proportional to the characteristic length of defect-atom interaction and increases with the increase of the temperature of the medium. The critical value of the pump parameter is directly proportional to recombination rate and inversely proportional to deformational potentials of defects.

scholarly journals Solving the Modified Regularized Long Wave Equations via Higher Degree B-Spline Algorithm

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Pshtiwan Othman Mohammed ◽  
Manar A. Alqudah ◽  
Y. S. Hamed ◽  
Artion Kashuri ◽  
Khadijah M. Abualnaja
Keyword(s):  
Solitary Waves ◽  
Wave Motion ◽  
Wave Equations ◽  
The Other ◽  
Collocation Methods ◽  
Spline Collocation ◽  
B Spline ◽  
Long Wave ◽  
Current Article ◽  
The Stability

The current article considers the sextic B-spline collocation methods (SBCM1 and SBCM2) to approximate the solution of the modified regularized long wave ( MRLW ) equation. In view of this, we will study the solitary wave motion and interaction of higher (two and three) solitary waves. Also, the modified Maxwellian initial condition into solitary waves is studied. Moreover, the stability analysis of the methods has been discussed, and these will be unconditionally stable. Moreover, we have calculated the numerical conserved laws and error norms L 2 and L ∞ to demonstrate the efficiency and accuracy of the method. The numerical examples are presented to illustrate the applications of the methods and to compare the computed results with the other methods. The results show that our proposed methods are more accurate than the other methods.

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