scholarly journals TURBULENCE GENERATED BY WAVE BREAKING ON BEACH

1982 ◽  
Vol 1 (18) ◽  
pp. 1 ◽  
Author(s):  
T. Sakai ◽  
Y. Inada ◽  
I. Sandanbata
Keyword(s):  
Vertical Distribution ◽  
Turbulence Intensity ◽  
Wave Breaking ◽  
Surf Zone ◽  
Turbulent Wake ◽  
Wave Period ◽  
Laser Doppler Velocimeter ◽  
Two Component ◽  
Hot Film ◽  
The Vertical Distribution

Horizontal and vertical velocities are measured with a hot-film anemometer (HFA) and a two-component laser-doppler velocimeter(LDV) in surf zones on uniform slopes of about 1/30 in two wave tanks. The turbulence generated by wave breaking is detected from the records. Following three aspects of the turbulence are discussed : (1) the distribution of the turbulence intensity in the surf zone, (2) the variation of the vertical distribution of the turbulence during one wave period and (3) the variation of the Reynolds stress during one wave period. It is found that the pattern of the distribution of the turbulence in the surf zone depends on the breaker type. A model is proposed, by extending the turbulent wake theory, to explain the variation of the vertical distribution of the turbulence during one wave period.

scholarly journals VERTICAL VARIATION OP UNDERTOW IN THE SURF ZONE

1988 ◽  
Vol 1 (21) ◽  
pp. 33 ◽  
Author(s):  
Akio Okayasu ◽  
Tomoya Shibayama ◽  
Kiyoshi Horikawa
Keyword(s):  
Laboratory Experiments ◽  
Eddy Viscosity ◽  
Surf Zone ◽  
Viscosity Coefficient ◽  
Laser Doppler Velocimeter ◽  
Vertical Variation ◽  
Two Component ◽  
The Mean ◽  
Eddy Viscosity Coefficient ◽  
The Vertical Distribution

In order to establish a model of the vertical distribution of the undertow, laboratory experiments were performed on uniform slopes of 1/20 and 1/30. The turbulent velocity in the surf zone including the area close to the bottom was measured by using a two-component laser doppler velocimeter. The distributions of the mean Reynolds stress and the mean eddy viscosity coefficient were calculated. Based on the experimental results, a model to predict the vertical profile of the undertow was presented.

scholarly journals Analytical Models of Velocity, Reynolds Stress and Turbulence Intensity in Ice-Covered Channels

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1107
Author(s):  
Jiao Zhang ◽  
Wen Wang ◽  
Zhanbin Li ◽  
Qian Li ◽  
Ya Zhong ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Reynolds Stress ◽  
Turbulence Intensity ◽  
Vertical Profile ◽  
Open Channel ◽  
Longitudinal Velocity ◽  
Analytical Formula ◽  
Ice Cover ◽  
Analytical Models ◽  
The Vertical Distribution

Ice cover in an open channel can influence the flow structure, such as the flow velocity, Reynolds stress and turbulence intensity. This study analyzes the vertical distributions of velocity, Reynolds stress and turbulence intensity in fully and partially ice-covered channels by theoretical methods and laboratory experiments. According to the experimental data, the vertical profile of longitudinal velocities follows an approximately symmetry form. Different from the open channel flow, the maximum value of longitudinal velocity occurs near the middle of the water depth, which is close to the channel bed with a smoother boundary roughness compared to the ice cover. The measured Reynolds stress has a linear distribution along the vertical axis, and the vertical distribution of measured turbulence intensity follows an exponential law. Theoretically, a two-power-law function is presented to obtain the analytical formula of the longitudinal velocity. In addition, the vertical profile of Reynolds stress is obtained by the simplified momentum equation and the vertical profile of turbulence intensity is investigated by an improved exponential model. The predicted data from the analytical models agree well with the experimental ones, thereby confirming that the analytical models are feasible to predict the vertical distribution of velocity, Reynolds stress and turbulence intensity in ice-covered channels. The proposed models can offer an important theoretical reference for future study about the sediment transport and contaminant dispersion in ice-covered channels.

scholarly journals VELOCITY FIELD UNDER PLUNGING WAVES

1986 ◽  
Vol 1 (20) ◽  
pp. 50 ◽  
Author(s):  
Akio Okayasu ◽  
Tomoya Shibayama ◽  
Nobuo Mimura
Keyword(s):  
Velocity Field ◽  
Laboratory Experiments ◽  
Surf Zone ◽  
Trough Level ◽  
Laser Doppler Velocimeter ◽  
Two Dimensional ◽  
Steady Current ◽  
Time Histories ◽  
Dimensional Distribution ◽  
Hot Film

In order to clarify the characteristics of the velocity field in the surf zone, three sets of detailed and precise two dimensional laboratory experiments were performed. Spatial distributions and time histories of velocity were measured by using a hot film velocimeter with a split type probe or a two components laser doppler velocimeter for regular wave conditions. Typical plunging breakers were formed during the experiments. Based on the experimental results, a model was investigated in order to estimate the two dimensional distribution of the on-offshore steady current below the trough level.

scholarly journals REYNOLDS STRESS IN SURF ZONE

1984 ◽  
Vol 1 (19) ◽  
pp. 3 ◽  
Author(s):  
T. Sakai ◽  
I. Sandanbata ◽  
M. Uchida
Keyword(s):  
Momentum Transfer ◽  
Reynolds Stress ◽  
Time Variation ◽  
Pipe Flow ◽  
Surf Zone ◽  
Momentum Equation ◽  
Laser Doppler ◽  
Wave Period ◽  
Laser Doppler Velocimeter ◽  
Sloping Beach

The on-offshore and the vertical components u, w of the velocity in a surf zone on a uniformly sloping beach in a wave tank were measured simultaneously with a laser-doppler velocimeter under two conditions. The time variation of the Reynolds stress -u'w' during one wave period is discussed. The Reynolds stress behaves as that in the oscillatory pipe flow does. The magnitude of the terms including the Reynolds stress terms in the on-offshore momentum equation is estimated. The Reynolds stress terms does not play any important role in the on-offshore momentum transfer during one wave period in the surf zone.

scholarly journals THE BOTTLENECK PROBLEM FOR TURBULENCE IN RELATION TO SUSPENDED SEDIMENT IN THE SURF ZONE

1986 ◽  
Vol 1 (20) ◽  
pp. 90
Author(s):  
Peter Justensen ◽  
Jorgen Fredsoe ◽  
Rolf Deigaard
Keyword(s):  
Boundary Layer ◽  
Kinetic Energy ◽  
Energy Level ◽  
Vertical Distribution ◽  
Turbulent Kinetic Energy ◽  
Suspended Sediment ◽  
Turbulence Model ◽  
Surf Zone ◽  
Wave Boundary ◽  
The Vertical Distribution

In the present paper the vertical distribution of turbulent kinetic energy k under broken waves is calculated by application of a one-equation turbulence model. The contributions to the energy level originate partly from the production in the wave boundary layer, partly from the production in the roller. Further on, the findings for k are used to calculate the vertical distribution of suspended sediment in broken waves.

scholarly journals FIELD MEASUREMENTS OF IMPACT PRESSURES IN SURF

1974 ◽  
Vol 1 (14) ◽  
pp. 103
Author(s):  
R.L. Miller ◽  
S. Leverette ◽  
J. O'Sullivan ◽  
J. Tochko ◽  
K. Theriault
Keyword(s):  
Vertical Distribution ◽  
Surf Zone ◽  
Field Measurements ◽  
Breaking Waves ◽  
Breaking Wave ◽  
Vertical Array ◽  
Qualitative Explanation ◽  
The Vertical Distribution ◽  
Plunging Breaker ◽  
Spilling Breaker

Field measurements were made of the vertical distribution of impact pressures exerted by breaking waves. Four distinct types are recognized and compared. These are near-breaking wave, plunging breaker, spilling breaker and post-breaking bore. The measurements were obtained by placing a 6 foot aluminum flat plate, backed by a cylinder in the surf zone, so that the fiat faced the approaching breakers. Five sensors were placed at one foot intervals on the flat. The sensors consisted of strain gage mounted aluminum diaphragms. Results indicated that impact pressure is significantly influenced by breaker type. The bore generated the largest impact pressures, followed in decreasing order by plunging breaker, spilling breaker and near breaking wave. In the vertical array, the largest impact pressures were recorded at or near the top, except for the bore where the reverse occurred. A qualitative explanation is given of various phenomena associated with impact pressures, by considering breaker mechanics.

Sign in / Sign up

Export Citation Format

Share Document