scholarly journals A numerical and experimental investigation of the effect of side walls on hydrodynamic model testing in a wave flume

2019 ◽  
Vol 186 ◽  
pp. 106108 ◽  
Author(s):  
N. Xie ◽  
M. Hann ◽  
R. Pemberton ◽  
G. Iglesias ◽  
D. Greaves
2021 ◽  
Vol 219 ◽  
pp. 108364
Author(s):  
Rafael Guimarães Pestana ◽  
Daniel Fonseca de Carvalho e Silva ◽  
Camila do Nascimento Gomes ◽  
Leonardo de Oliveira Carvalho ◽  
Vinicius Vileti ◽  
...  

Author(s):  
T. Rajesh Kannah ◽  
R. Natarajan

An experimental investigation on the dynamic behaviour of a typical internal turret moored FPSO system with a turret located at midships position is reported. A 1:100 scale model of 140000t DWT turret moored FPSO system was tested under regular waves for three operating conditions i.e. 40%DWT, 70%DWT and 100%DWT in a 2m wide wave flume at a water depth of 1m for the wave frequencies from 0.55Hz to 1.25Hz in steps of 0.04Hz. The motions were measured by rotary type potentiometers and specially ring type load cells were used to measure the mooring forces. The model tests results are analysed and presented with discussions in this paper.


2012 ◽  
Vol 711 ◽  
pp. 101-121 ◽  
Author(s):  
Y. Ma ◽  
G. Dong ◽  
M. Perlin ◽  
X. Ma ◽  
G. Wang

AbstractAn experimental investigation focusing on the effect of dissipation on the evolution of the Benjamin–Feir instability is reported. A series of wave trains with added sidebands, and varying initial steepness, perturbed amplitudes and frequencies, are physically generated in a long wave flume. The experimental results directly confirm the stabilization theory of Segur et al. (J. Fluid Mech., vol. 539, 2005, pp. 229–271), i.e. dissipation can stabilize the Benjamin–Feir instability. Furthermore, the experiments reveal that the effect of dissipation on modulational instability depends strongly on the perturbation frequency. It is found that the effect of dissipation on the growth rates of the sidebands for the waves with higher perturbation frequencies is more evident than on those of waves with lower perturbation frequencies. In addition, numerical simulations based on Dysthe’s equation with a linear damping term included, which is estimated from the experimental data, can predict the experimental results well if the momentum integral of the wave trains is conserved during evolution.


1997 ◽  
Vol 119 (4) ◽  
pp. 292-297 ◽  
Author(s):  
B. A. Jubran ◽  
J. A. Iweida ◽  
N. M. Haimour

This paper reports an experimental investigation to study the effect of various parameters that might affect the generation of convective cells in solar ponds with sloping walls. The parameters studied include the variation of the angles of the walls, types of salt used, and the surface roughness of the sloping wall. Four angles were used: 90, 60, 45 and 30, as well as four different types of salts: sodium chloride, potassium chloride, ammonium Sulphate, and carnalite. It was found that increasing the sloping angle of the heated wall of the pond tends to decrease the activity of the convective cells. Furthermore, the growth rate of the convective cells is very much dependent on the type of salt. The results indicate that carnalite and ammonium sulphate tend to have low growth rates of convective cells compared with sodium chloride and potassium chloride. Finally, the surface roughness of the heated wall tends to reduce the activity of the convective cells.


Author(s):  
Jaromír Jílek

A detailed experimental investigation of the three-dimensional subsonic flow was carried out in a typical nozzle and impulse configuration of plane turbine cascades with a chord length 0.5 m. Flow parameters were measured within the passage and behind the cascade using a five-hole probe. Pressure distribution measurements and flow visualization were made on blade surfaces and side walls. Flow measurements were taken in endwall and airfoil boundary layers for both types of cascades. The influence of the aspect ratio, the inlet side wall boundary layer and the position of traversing planes on aerodynamic characteristics and losses is discussed.


Author(s):  
Christian Schmittner ◽  
Joris Brouwer ◽  
Janou Hennig

For hydrodynamic model testing different types of model waves are applied, where the most common ones are regular (monochromatic) and irregular (multichromatic) waves. In addition to these wave types the application of focusing wave groups, which are also often denoted as wave packages or transient wave packets, can give insight into aspects that cannot be assessed by the conventional model waves. This paper describes the different applications of focusing wave groups for hydrodynamic model testing. The paper starts with the historical background, followed by a theoretical description and the generation procedure. The main part of the paper is dedicated to the practical application of focusing wave groups in the basin. Items that will be described are a) the derivation of transfer functions for floating structures and for anti-roll tanks b) the determination of hydraulic and electrical transfer function of wave makers c) the verification of position and calibration of wave probes in the basin d) the generation of extreme wave events e) the assessment of reflection coefficient of beaches f) the investigation of non-linear aspects of transfer functions. Finally, characteristics of the analysis of focusing waves are introduced and compared to conventional methods based on regular and irregular waves.


2011 ◽  
Vol 1 (32) ◽  
pp. 43
Author(s):  
Betsy S. Hicks ◽  
Nobuhisa Kobayashi ◽  
Jack A. Puleo ◽  
Ali Farhadzadeh

A numerical and experimental investigation of profile evolution was completed on a laboratory gravel beach. A total of four tests were completed on a gravel beach constructed in a small-scale wave flume, with different incident wave conditions and initial beach slopes. The tests allowed for an examination of erosional, accretional, and migratory bar conditions as well as how the differences affected the final quasi-equilibrium profiles. Profile evolution and hydrodynamic data were collected for comparison with the time- and depth- averaged numerical model CSHORE. The numerical formulations developed for damage progression on a stone armor layer were found to predict the profile evolution on the steeper test conditions but required modifications to the bedload formula to better predict the accretional and bar migration tests.


Author(s):  
Michael G. Morabito

The design of successful water-based aircraft requires a close collaboration between the aeronautical engineers and naval architects, who perform high-speed towing tests, stability calculations, or computational fluid dynamics in support of the design. This article presents the fundamental design considerations of waterborne aircraft, which are outside of the typical educational scope of most naval architects, but which they are sometimes asked to address. These include 1) the hydrostatic and hydrodynamic problems associated with seaplane design, 2) early-stage methods for sizing the hull, 3) prediction techniques using archival data, and 4) hydrodynamic model testing procedures. Although a new design will often require substantial iteration to achieve the desired outcome, the information in this article will assist in developing a reasonable starting point for the design spiral and provides sufficient details for a hydrodynamic model testing facility to perform a successful series of model tests on the design. Although much of the work in this field dates from the 1940s, it is important to review this material in light of the current practices being used at hydrodynamic research facilities today. A detailed description of the model testing apparatus and procedure, used in a recent study at the U.S. Naval Academy, is presented to demonstrate the current applicability of these methods and some pitfalls that can be expected in testing.


1986 ◽  
Vol 1 (20) ◽  
pp. 86 ◽  
Author(s):  
J. Buhr Hansen ◽  
Ib. A. Svendsen

The results presented in this paper are from a series of experiments in a wave flume modelling the onshore-offshore water motions over a bar bottom profile. In a true 3-dimensional natural situation the flow of water over the bar varies along the coast. In the experiments the flow of water over the bar is simulated by a controlled discharge through the flume.


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