Calibration of a 58 m wave flume

1981 ◽  
Vol 8 (4) ◽  
pp. 449-455 ◽  
Author(s):  
D. B. Muggeridge ◽  
J. J. Murray
Keyword(s):  
Wave Height ◽  
Water Depth ◽  
Random Wave ◽  
Regular Waves ◽  
M Wave ◽  
Wave Flume ◽  
Wind Speeds ◽  
On Line ◽  
Predicted Values ◽  
Good Agreement

A 58.27 × 4.57 × 3.04 m wave flume has been constructed and calibrated. The maximum wave height that can be generated in regular waves is 0.7 m at a water depth of 1.8 m. Random wave spectra have also been modelled in the flume for prototype wind speeds up to 25 m/s. The maximum significant wave height that can be generated at a 1 m water depth is 20 cm.A series of tests performed to verify design curves presented by Gilbert, Thompson, and Brewer show good agreement with the predicted values. The Pierson-Moskowitz spectrum was modelled between wind speeds of 5 and 25 m/s at suitable scale factors ranging from 1:50 to 1:150. All analysis was carried out in real time by means of an on-line computer.

scholarly journals Nonlinear run-ups of regular waves on sloping structures

2012 ◽  
Vol 12 (12) ◽  
pp. 3811-3820 ◽  
Author(s):  
T.-W. Hsu ◽  
S.-J. Liang ◽  
B.-D. Young ◽  
S.-H. Ou
Keyword(s):  
Boussinesq Equations ◽  
Irregular Waves ◽  
Coastal Structures ◽  
Regular Waves ◽  
Wave Flume ◽  
Coastal Risk ◽  
Run Up ◽  
Two Parameters ◽  
Prediction Capability ◽  
Good Agreement

Abstract. For coastal risk mapping, it is extremely important to accurately predict wave run-ups since they influence overtopping calculations; however, nonlinear run-ups of regular waves on sloping structures are still not accurately modeled. We report the development of a high-order numerical model for regular waves based on the second-order nonlinear Boussinesq equations (BEs) derived by Wei et al. (1995). We calculated 160 cases of wave run-ups of nonlinear regular waves over various slope structures. Laboratory experiments were conducted in a wave flume for regular waves propagating over three plane slopes: tan α =1/5, 1/4, and 1/3. The numerical results, laboratory observations, as well as previous datasets were in good agreement. We have also proposed an empirical formula of the relative run-up in terms of two parameters: the Iribarren number ξ and sloping structures tan α. The prediction capability of the proposed formula was tested using previous data covering the range ξ ≤ 3 and 1/5 ≤ tan α ≤ 1/2 and found to be acceptable. Our study serves as a stepping stone to investigate run-up predictions for irregular waves and more complex geometries of coastal structures.

scholarly journals RANDOM BREAKING WAVES HORIZONTAL SEABED

1986 ◽  
Vol 1 (20) ◽  
pp. 68 ◽  
Author(s):  
Hans Peter Riedel ◽  
Anthony Paul Byrne
Keyword(s):  
Wave Height ◽  
Water Depth ◽  
Breaking Waves ◽  
Random Wave ◽  
Random Waves ◽  
Flume Experiments ◽  
Depth Ratio ◽  
Wave Trains ◽  
Monochromatic Waves

According to wave theories the depth limited wave height over a horizontal seabed has a wave height to water depth ratio (H/d) of about 0.8. Flume experiments with monochromatic waves over a horizontal seabed have failed to produce H/d ratios greater than 0.55. However designers still tend to use H/d 0.8 for their design waves. Experiments have been carried out using random wave trains in the flume over a horizontal seabed. These experiments have shown that the limiting H/d ratio of 0.55 applies equally well to random waves.

Wave Transmission over the Low-Crested Sand Container Breakwaters

2015 ◽  
Vol 802 ◽  
pp. 57-62
Author(s):  
Hee Min Teh
Keyword(s):  
Shallow Water ◽  
Transmission Coefficient ◽  
Water Depth ◽  
Wave Transmission ◽  
Experimental Result ◽  
Regular Waves ◽  
Wave Flume ◽  
Test Models ◽  
Wave Transmission Coefficient ◽  
Transmission Ability

Breakwaters made of sand container is one of the most economical options for wave protection at coastal areas. These breakwaters have been adopted with mixed success at several locations in Malaysia. Nevertheless, the performance of these structure has not been properly studied and documented to date. This study is undertaken to study the wave transmission ability of the submerged sand container breakwater with respect to its width and height as well as the water depth. A number of experiments have been conducted in a wave flume to quantify the wave transmission coefficient of the test models of different layouts when exposed to regular waves. The experimental result has shown that the breakwater is effective in arresting the shorter period waves, particularly in shallow water. The height of the breakwater has to be increased in order to arrest the longer period waves.

scholarly journals MACRO-TURBULENCE FROM WIND WAVES

1970 ◽  
Vol 1 (12) ◽  
pp. 14 ◽  
Author(s):  
Chin-Yuan Lee ◽  
Frank D. Masch
Keyword(s):  
Energy Dissipation ◽  
Wave Height ◽  
Wind Waves ◽  
Wave Energy Dissipation ◽  
Wave Flume ◽  
Wind Speeds ◽  
Macro Scale ◽  
Scale Turbulence ◽  
Almost All ◽  
Hot Film

Laboratory studies m a wind wave flume were carried out to investigate the macro-scale turbulence associated with wind waves and white cap conditions Velocity fluctuations m water were measured with a hot film anemometer and parametric correlations between wind waves and turbulence characteristics were established Measured data were recorded m analog form, digitized and stored on magnetic tape Auto - covanance functions and power spectral density functions were then obtained for all sample records Results showed that the depth of the penetration of the macro-scale turbulence increased rapidly with wind speed but the rate of penetration diminished at the higher wind speeds This rate of macro-turbulence penetration was found to vary inversely with wave height and wave steepness Most turbulent fluctuations having frequencies equal to or higher than the frequency of the ambient surface waves were confined to the zone of macro-turbulence penetration although some disturbances such as vortex rings and other turbulence associated with white cap wave conditions occasionally penetrated to greater depths It was found that the energy dissipation increased with wave height and that almost all wave energy dissipation was concentrated near the water surface.

scholarly journals TRANSMISSION OF REGULAR WAVES PAST FLOATING PLATES

1974 ◽  
Vol 1 (14) ◽  
pp. 112
Author(s):  
Uygur Sendil ◽  
W.H. Graf
Keyword(s):  
Water Depth ◽  
Wave Length ◽  
Wave Theory ◽  
Finite Amplitude ◽  
Linear Wave ◽  
Regular Waves ◽  
Transmission Coefficients ◽  
Wave Flume ◽  
Wave Heights ◽  
Incident Waves

Theoretical solutions for the transmission beyond and reflection of waves from fixed and floating plates are based upon linear wave theory, as put forth by John (1949), and Stoker (1957), according to which the flow is irrotational, the fluid is incompressible and frictionless, and the waves are of small amplitude. The resulting theoretical relations are rather complicated, and furthermore, it is assumed that the water depth is very small in comparison to the wave length. Wave transmissions beyond floating horizontal plates are studied in a laboratory wave flume. Regular (harmonic) waves of different heights and periods are generated. The experiments are carried out over a range of wave heights from 0.21 to 8.17 cm (0.007 to 0.268 ft), and wave periods from 0.60 to 4.00 seconds in water depth of 15.2, 30.5, and 45.7 cm (0.5, 1.0 and 1.5 ft). Floating plates of 61, 91 and 122 cm (2, 3 and 4 ft) long were used. From the analyses of regular waves it was found that: (1) the transmission coefficients, H /H , obtained from the experiments are usually less than those obtained from the theory. This is due to the energy dissipation by the plate, which is not considered in the theory. (2) John's (1949) theory predicts the transmission coefficients, H /H , reasonably well for a floating plywood plate, moored to the bottom and under the action of non-breaking incident waves of finite amplitude. (3) a floating plate is less effective in damping the incident waves than a fixed plate of the same length.

An Experimental Study of Effects of Water Depth on Wave Scattering and Motion Responses of a Moored Floating Breakwater in Regular Waves

2011 ◽  
Author(s):  
Zhenhua Huang ◽  
Wenbin Zhang
Keyword(s):  
Water Depth ◽  
Measurement Unit ◽  
Regular Waves ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Wave Flume ◽  
Motion Responses ◽  
Floating Breakwater ◽  
Series Of Experiments ◽  
Floating Breakwaters

Due to the mobility and low costs, floating breakwaters have been frequently considered as alternatives for protecting marinas and harbors from wave attacks. Main advantages of using floating breakwaters include (i) the exchange of water between a harbor and ocean, and (ii) an adjustable elevation varying with tidal levels. When floating breakwaters are used in shallow water environments (during low tides), the presence of seabed may affect the dynamics of the floating breakwaters. In the present study, a series of experiments were carried out in a wave flume of 1.5m wide and 45m long to study the effects of water depth on the performance of a moored floating breakwater. An inertial measurement unit mounted on the breakwater measures the motion responses. The wave reflection and transmission coefficients and the responses of the breakwater to regular waves are presented for four difference water depths.

scholarly journals WAVE-FLUME EXPERIMENTS OF DISSIPATING WAVES ON SOFT MUD

2011 ◽  
Vol 1 (32) ◽  
pp. 4
Author(s):  
Mohsen Soltanpour ◽  
Farzin Samsami ◽  
Soroush Sorourian
Keyword(s):  
Shear Rate ◽  
Wave Attenuation ◽  
Interaction Model ◽  
Rheological Parameters ◽  
Regular Waves ◽  
Flume Experiments ◽  
Flow Curves ◽  
Attenuation Coefficients ◽  
Wave Flume ◽  
Good Agreement

A series of laboratory wave-flume experiments was conducted to investigate the dissipation of monochromatic regular waves on a horizontal muddy bed of commercial kaolinite. The rheological parameters of kaolinite samples with different water content ratios were obtained from controlled shear rate tests using the rheometer. The flow curves of shear stress versus shear rate were found to be essentially Bingham viscoplastic medium for steady unidirectional mud flows of the rheological tests. Assuming Bingham behavior for kaolinite, a wave-mud interaction model was employed to obtain the values of the wave attenuation coefficients. Comparisons between the measured and simulated results show a good agreement.

scholarly journals Time Scale for Scour Beneath Pipelines Due to Long-Crested and Short-Crested Nonlinear Random Waves Plus Current

2021 ◽  
Vol 9 (2) ◽  
pp. 114
Author(s):  
Dag Myrhaug ◽  
Muk Chen Ong
Keyword(s):  
Time Scale ◽  
Current Flow ◽  
Irregular Waves ◽  
Wave Crest ◽  
Random Wave ◽  
Random Waves ◽  
Flow Conditions ◽  
Regular Waves ◽  
Nonlinear Random Waves ◽  
2D And 3D

This article derives the time scale of pipeline scour caused by 2D (long-crested) and 3D (short-crested) nonlinear irregular waves and current for wave-dominant flow. The motivation is to provide a simple engineering tool suitable to use when assessing the time scale of equilibrium pipeline scour for these flow conditions. The method assumes the random wave process to be stationary and narrow banded adopting a distribution of the wave crest height representing 2D and 3D nonlinear irregular waves and a time scale formula for regular waves plus current. The presented results cover a range of random waves plus current flow conditions for which the method is valid. Results for typical field conditions are also presented. A possible application of the outcome of this study is that, e.g., consulting engineers can use it as part of assessing the on-bottom stability of seabed pipelines.

scholarly journals Seasonal Estimates and Uncertainties of Snow Accumulation from CloudSat Precipitation Retrievals

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 363
Author(s):  
George Duffy ◽  
Fraser King ◽  
Ralf Bennartz ◽  
Christopher G. Fletcher
Keyword(s):  
Time Scales ◽  
Snow Water Equivalent ◽  
Spatial Scales ◽  
Snow Accumulation ◽  
High Latitudes ◽  
Percentage Points ◽  
Snow Water ◽  
Time Periods ◽  
Predicted Values ◽  
Good Agreement

CloudSat is often the only measurement of snowfall rate available at high latitudes, making it a valuable tool for understanding snow climatology. The capability of CloudSat to provide information on seasonal and subseasonal time scales, however, has yet to be explored. In this study, we use subsampled reanalysis estimates to predict the uncertainties of CloudSat snow water equivalent (SWE) accumulation measurements at various space and time resolutions. An idealized/simulated subsampling model predicts that CloudSat may provide seasonal SWE estimates with median percent errors below 50% at spatial scales as small as 2° × 2°. By converting these predictions to percent differences, we can evaluate CloudSat snowfall accumulations against a blend of gridded SWE measurements during frozen time periods. Our predictions are in good agreement with results. The 25th, 50th, and 75th percentiles of the percent differences between the two measurements all match predicted values within eight percentage points. We interpret these results to suggest that CloudSat snowfall estimates are in sufficient agreement with other, thoroughly vetted, gridded SWE products. This implies that CloudSat may provide useful estimates of snow accumulation over remote regions within seasonal time scales.

Estimation of the Thermodynamic Properties of Branched Hydrocarbons

2000 ◽  
Vol 122 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Hui He ◽  
Mohamad Metghalchi ◽  
James C. Keck
Keyword(s):  
Thermodynamic Properties ◽  
Degrees Of Freedom ◽  
Statistical Thermodynamic ◽  
Motion Modes ◽  
Branched Alkanes ◽  
Branched Hydrocarbons ◽  
Wide Range ◽  
On Line ◽  
Kinetic Calculations ◽  
Good Agreement

A simple model has been developed to estimate the sensible thermodynamic properties such as Gibbs free energy, enthalpy, heat capacity, and entropy of hydrocarbons over a wide range of temperatures with special attention to the branched molecules. The model is based on statistical thermodynamic expressions incorporating translational, rotational and vibrational motions of the atoms. A method to determine the number of degrees of freedom for different motion modes (bending and torsion) has been established. Branched rotational groups, such as CH3 and OH, have been considered. A modification of the characteristic temperatures for different motion mode has been made which improves the agreement with the exact values for simple cases. The properties of branched alkanes up to 2,3,4,-trimthylpentane have been calculated and the results are in good agreement with the experimental data. A relatively small number of parameters are needed in this model to estimate the sensible thermodynamic properties of a wide range of species. The model may also be used to estimate the properties of molecules and their isomers, which have not been measured, and is simple enough to be easily programmed as a subroutine for on-line kinetic calculations. [S0195-0738(00)00902-X]

Sign in / Sign up

Export Citation Format

Share Document