scholarly journals INCIPIENT MOTION OF PARTICLES UNDER OSCILLATORY FLOW

1982 ◽  
Vol 1 (18) ◽  
pp. 94
Author(s):  
L. Lenhoff
Keyword(s):  
Reynolds Number ◽  
Sediment Transport ◽  
Oscillatory Flow ◽  
Coastal Engineering ◽  
Incipient Motion ◽  
Flow Data ◽  
National Research Institute ◽  
Predictive Equations ◽  
Engineering Problems ◽  
Coastal Sediment Transport

This paper is aimed at the establishment of a generally applicable criterion for the onset of grain motion under the influence of oscillatory flow. Data from previous studies are used in a dimensional analysis and an empirically derived relationship between the dimensionless parameters R* (shear Reynolds number) and D* (dimensionless grain parameter) is proposed as a criterion to be used in coastal engineering problems. This study forms part of a larger programme by the Sediment Dynamics Division of the National Research Institute for Oceanology in Stellenbosch, RSA, which is aimed at the reevaluation and updating of the input parameters and relationships for the predictive equations for coastal sediment transport.

scholarly journals PREDICTIVE EQUATIONS REGARDING COASTAL TRANSPORTS

1976 ◽  
Vol 1 (15) ◽  
pp. 65 ◽  
Author(s):  
D.H. Swart
Keyword(s):  
Sediment Transport ◽  
Morphological Changes ◽  
Predictive Equations ◽  
Practical Applications ◽  
Engineering Problems

Morphological changes are the result of gradients in longshore and onshore-offshore sediment transport. The coastal engineer is continually faced with engineering problems in which a quantitative knowledge of these morphological changes is required. For this purpose predictive equations have been developed for both longshore and onshore-offshore sediment transport, which are being used in practical applications. In this paper a few of these predictive techniques, as well as one of their typical applications, viz. to a beachfill problem, will be discussed.

scholarly journals TRANSIENT RIPPLE FORMATION AND SEDIMENT TRANSPORT

1986 ◽  
Vol 1 (20) ◽  
pp. 120
Author(s):  
Suphat Vongvisessomjai ◽  
L.C.J. Munasinghe ◽  
P.P. Gunaratna
Keyword(s):  
Sediment Transport ◽  
Surface Waves ◽  
Coastal Engineering ◽  
Transport Rate ◽  
Beach Morphology ◽  
Ripple Formation ◽  
Engineering Problems ◽  
Successful Measurement ◽  
And Migration ◽  
Rates Of Growth

A knowledge of sediment transport rates due to wave action is essential for an understanding of various coastal engineering problems. Many problems have to be resolved before successful measurement can be made for sediment transport rates due to waves. Since gradients of sediment transport cause changes of beach morphology, the sediment transport rate outside breaker can be determined from measured beach changes. Measurements of ripple growth and migration yield their mathematical descriptions in the same manner as those of surface waves. Expressions of sediment transport rates are then derived. It is found from the study that the sediment transport rates are strongly controlled by the rates of growth and migration of ripples.

Sediment Transport and Backfilling of Trenches in Oscillatory Flow

2001 ◽  
Vol 127 (5) ◽  
pp. 272-281 ◽  
Author(s):  
Jacob Hjelmager Jensen ◽  
Jørgen Fredsøe
Keyword(s):  
Sediment Transport ◽  
Oscillatory Flow

The development of asymmetry and period doubling for oscillatory flow in baffled channels

1996 ◽  
Vol 328 ◽  
pp. 19-48 ◽  
Author(s):  
E. P. L. Roberts ◽  
M. R. Mackley
Keyword(s):  
Reynolds Number ◽  
Oscillatory Flow ◽  
Three Dimensional ◽  
Period Doubling ◽  
Progressive Increase ◽  
Newtonian Flow ◽  
Chaotic Flow ◽  
Spatially Periodic ◽  
Dimensional Simulation ◽  
Time Periodic

We report experimental and numerical observations on the way initially symmetric and time-periodic fluid oscillations in baffled channels develop in complexity. Experiments are carried out in a spatially periodic baffled channel with a sinusoidal oscillatory flow. At modest Reynolds number the observed vortex structure is symmetric and time periodic. At higher values the flow progressively becomes three-dimensional, asymmetric and aperiodic. A two-dimensional simulation of incompressible Newtonian flow is able to follow the flow pattern at modest oscillatory Reynolds number. At higher values we report the development of both asymmetry and a period-doubling cascade leading to a chaotic flow regime. A bifurcation diagram is constructed that can describe the progressive increase in complexity of the flow.

scholarly journals LONGSHORE TRANSPORT AT A TOTAL LITTORAL BARRIER

1976 ◽  
Vol 1 (15) ◽  
pp. 70 ◽  
Author(s):  
Richard O. Bruno ◽  
Christopher G. Gable
Keyword(s):  
Sediment Transport ◽  
Accurate Determination ◽  
Coastal Engineering ◽  
Channel Islands ◽  
Shore Protection ◽  
Material Transport ◽  
Engineering Research ◽  
Longshore Sediment Transport ◽  
Longshore Transport

Analysis of longshore transport at a littoral barrier is presented. Channel Islands Harbor, California was selected as the study site because its offshore breakwater and jetties form a unique complete littoral barrier. Through repetitive surveys an accurate determination of longshore material transport in one direction was made. Measured transport rates ranged from 160,000 to 1,284,000 cubic meters per year. Utilizing visual observations of surf parameters, estimates of longshore wave thrust were computed. The range of wave thrust was 145 to 1,988 Newtons per meter. Comparison of the relation of wave thrust and longshore sediment transport is made. This study indicates that in an environment of high transport, nearly twice as much transport is predicted tinder corresponding wave thrust as that of the data summarized in the Coastal Engineering Research Center's Shore Protection Manual.

Sign in / Sign up

Export Citation Format

Share Document