Water Wave Interaction on a Truncated Vertical Cylinder

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Octavi Sadó Garriga ◽  
Jeffrey M. Falzarano
Keyword(s):  
Free Surface ◽  
New Orleans ◽  
Frequency Estimation ◽  
Vertical Cylinder ◽  
Wave Interaction ◽  
Experimental Results ◽  
Oscillating Water Column ◽  
Towing Tank ◽  
The University ◽  
Moon Pool

The purpose of this paper is to combine and extend existing potential flow theory in order to analyze the linear free surface problem of an oscillating water column (OWC) device and apply it to moon pool design. Analytical results were obtained implementing the previously derived theories, and later compared to experimental results conducted at the University of New Orleans Towing Tank. The model tests consisted of a study of a cylindrical OWC. The theoretical and experimental results of the free surface for the OWC tests agree for the resonant frequency estimation response but they disagree on the amplitude of the response.

Water Waves and Marine Structure Interaction

2004 ◽  
Author(s):  
Octavi Sado´ Garriga ◽  
Jeffrey M. Falzarano
Keyword(s):  
Free Surface ◽  
New Orleans ◽  
Water Waves ◽  
Frequency Estimation ◽  
Experimental Results ◽  
Oscillating Water Column ◽  
Towing Tank ◽  
Structure Interaction ◽  
Marine Structure ◽  
The University

The purpose of this paper is to combine and extend existing potential flow theory in order to analyze the linear free surface problem of an Oscillating Water Column (OWC) device and apply it to moonpool design. Analytical results were obtained implementing the previously derived theories, and later compared to experimental results conducted at the University of New Orleans Towing Tank. The model tests consisted of a study of a cylindrical OWC. The theoretical and experimental results of the free surface for the OWC tests agree for the resonant frequency estimation response but they disagree on the amplitude of the response.

scholarly journals Mathematical modelling of the overflowing cylinder experiment

2003 ◽  
Vol 474 ◽  
pp. 275-298 ◽  
Author(s):  
P. D. HOWELL ◽  
C. J. W. BREWARD
Keyword(s):  
Free Surface ◽  
Surfactant Concentration ◽  
Dynamic Properties ◽  
Vertical Cylinder ◽  
Surfactant Solution ◽  
Surface Concentration ◽  
Experimental Results ◽  
Surface Velocity ◽  
Experimental Apparatus ◽  
Finite Distance

The overflowing cylinder (OFC) is an experimental apparatus designed to generate a controlled straining flow at a free surface, whose dynamic properties may then be investigated. Surfactant solution is pumped up slowly through a vertical cylinder. On reaching the top, the liquid forms a flat free surface which expands radially before over flowing down the side of the cylinder. The velocity, surface tension and surfactant concentration on the expanding free surface are measured using a variety of non-invasive techniques.A mathematical model for the OFC has been previously derived by Breward et al. (2001) and shown to give satisfactory agreement with experimental results. However, a puzzling indeterminacy in the model renders it unable to predict one scalar parameter (e.g. the surfactant concentration at the centre of the cylinder), which must be therefore be taken from the experiments.In this paper we analyse the OFC model asymptotically and numerically. We show that solutions typically develop one of two possible singularities. In the first, the surface concentration of surfactant reaches zero a finite distance from the cylinder axis, while the surface velocity tends to infinity there. In the second, the surfactant concentration is exponentially large and a stagnation point forms just inside the rim of the cylinder. We propose a criterion for selecting the free parameter, based on the elimination of both singularities, and show that it leads to good agreement with experimental results.

Design of the University of New Orleans Ship-Offshore University Laboratory for Offshore Industry Support

1988 ◽  
Vol 110 (3) ◽  
pp. 133-140 ◽  
Author(s):  
R. Latorre
Keyword(s):  
New Orleans ◽  
Water Current ◽  
Offshore Structure ◽  
Water Research ◽  
Towing Tank ◽  
Calm Water ◽  
Tank Design ◽  
Offshore Industry ◽  
The University ◽  
University Laboratory

On July 23, 1987, the University of New Orleans (UNO) dedicated its new Engineering Building, which houses a 38.3 m×4.57 m×0–2.134 m deep ship-offshore university laboratory tow tank. This paper covers the initial stages of the project and summarizes the towing tank design for ship-offshore testing. The tank is configured for three purposes: 1) conventional ship research in deep water with calm water or waves; 2) offshore structure testing with provision for observation and anchoring; 3) shallow water research in calm water, current, and waves.

Numerical Simulation of the Oscillating Water Column inside a Vertical Cylinder in Regular Waves Using IHFOAM

2017 ◽  
Vol 372 ◽  
pp. 40-49
Author(s):  
J.M.P. Conde ◽  
J.M.S.M. Cardoso
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Water Column ◽  
Vertical Cylinder ◽  
Cylindrical Tube ◽  
Numerical Results ◽  
Navier Stokes ◽  
Oscillating Water Column ◽  
Good Correspondence ◽  
Ocean Wave Energy

The motion of the free-surface inside a surface-piercing vertical cylindrical tube can be seen as a simplified approximation of an oscillating-water-column ocean-wave energy-converter (OWC-OWEC). In the present work the IHFOAM code, which solves the Reynolds-averaged Navier-Stokes (RANS) equations by a finite-volume method using the volume-of-fluid (VoF) technique, was used to simulate the action of a regular wave on the free-surface inside a vertical cylinder open to the atmosphere. In this paper the results obtained by IHFOAM are compared with other numerical results and with experimental data, showing a good correspondence between these results. In this way the IHFOAM code was verified (by comparison with other numerical results) and validated (by comparison with experimental data).

Comments on Second-Order Wave Effects on Large-Diameter Vertical Cylinder

1978 ◽  
Vol 22 (04) ◽  
pp. 266-268
Author(s):  
Subrata K. Chakrabarti
Keyword(s):  
Free Surface ◽  
Large Diameter ◽  
Vertical Cylinder ◽  
Wave Interaction ◽  
Scattered Wave ◽  
Second Order ◽  
Surface Boundary ◽  
Order Solution ◽  
Free Surface Boundary Condition ◽  
Surface Boundary Conditions

In a recent paper, Raman et al (RJV) [1] 2 presented a second- order solution for the wave interaction with a large-diameter, bottom-mounted, surface-piercing, fixed vertical cylinder. Earlier, Chakrabarti [2,3] obtained an approximate solution for the vertical cylinder due to Stokes's fifth-order wave. Later, Yamaguchi and Tsuchiya (YT) [4] proposed a second-order solution in a closed form for the wave interaction problem with the vertical cylinder which was examined by Chakrabarti [5]. All these solutions are different due to the assumptions regarding the frequency of the scattered wave and the kinematic free-surface boundary condition. RJV [1] claim that their solution is superior to the earlier solutions because, according to them, it satisfies the nonlinear free-surface boundary conditions completely.

Computation of Wave Impact Pressures and Kinematics During Plunging Breaking Wave Interaction With a Vertical Cylinder Using CFD Modelling

2017 ◽  
Author(s):  
Mayilvahanan Alagan Chella ◽  
Hans Bihs ◽  
Dag Myrhaug ◽  
Øivind Asgeir Arntsen
Keyword(s):  
Free Surface ◽  
Vertical Cylinder ◽  
Wave Interaction ◽  
Breaking Waves ◽  
Offshore Wind Turbine ◽  
Breaking Wave ◽  
Total Force ◽  
Wave Impact ◽  
Large Wave ◽  
Surface Deformations

Wave loads from breaking waves on offshore wind turbine (OWT) substructures in shallow waters still remain uncertain. The interaction of breaking waves with structures is characterized by complex free surface deformations, instantaneous impact of the water mass against the structure and consequently large wave forces on the structures. The main objective of the paper is to investigate wave impact pressures and kinematics during the interaction of breaking waves with a vertical cylinder using the open-source CFD model REEF3D. The model is based on the Reynolds-Averaged Navier-Stokes (RANS) equations coupled with the level set method (LSM) and k-ω turbulence model. Three wave impact conditions are considered in the present study. The numerically simulated free surface deformations around the cylinder during the breaking wave interaction are also presented for different wave impact conditions. For three wave impact conditions, the wave impact pressure and the horizontal and vertical components of the particle velocity are computed in front of the cylinder and analyzed. The pressure and velocity profile at their maximum values are also examined and discussed. In addition, the total force is calculated for three breaking conditions and they are correlated with the pressure and kinematics during the interaction.

scholarly journals A Synopsis Based Approach for Itemset Frequency Estimation over Massive Multi-Transaction Stream

2021 ◽  
Vol 16 (2) ◽  
pp. 1-30
Author(s):  
Guangtao Wang ◽  
Gao Cong ◽  
Ying Zhang ◽  
Zhen Hai ◽  
Jieping Ye
Keyword(s):  
Frequency Estimation ◽  
Frequent Itemsets ◽  
Frequent Itemset ◽  
Experimental Results ◽  
Closure Property ◽  
Frequent Itemset Mining ◽  
Itemset Mining ◽  
Minimum Value ◽  
Downward Closure ◽  
Bounded Size

The streams where multiple transactions are associated with the same key are prevalent in practice, e.g., a customer has multiple shopping records arriving at different time. Itemset frequency estimation on such streams is very challenging since sampling based methods, such as the popularly used reservoir sampling, cannot be used. In this article, we propose a novel k -Minimum Value (KMV) synopsis based method to estimate the frequency of itemsets over multi-transaction streams. First, we extract the KMV synopses for each item from the stream. Then, we propose a novel estimator to estimate the frequency of an itemset over the KMV synopses. Comparing to the existing estimator, our method is not only more accurate and efficient to calculate but also follows the downward-closure property. These properties enable the incorporation of our new estimator with existing frequent itemset mining (FIM) algorithm (e.g., FP-Growth) to mine frequent itemsets over multi-transaction streams. To demonstrate this, we implement a KMV synopsis based FIM algorithm by integrating our estimator into existing FIM algorithms, and we prove it is capable of guaranteeing the accuracy of FIM with a bounded size of KMV synopsis. Experimental results on massive streams show our estimator can significantly improve on the accuracy for both estimating itemset frequency and FIM compared to the existing estimators.

scholarly journals Laminar free-surface flow into a vertical cylinder

1975 ◽  
Vol 3 (1) ◽  
pp. 51-68 ◽  
Author(s):  
Thomas G. Smith ◽  
J.O. Wilkes
Keyword(s):  
Free Surface ◽  
Vertical Cylinder ◽  
Free Surface Flow ◽  
Surface Flow

Experimental Study of a Tanker Ship Squat in Shallow Water

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
Mohammadreza Fathi Kazerooni ◽  
Mohammad Saeed Seif
Keyword(s):  
Experimental Study ◽  
Shallow Water ◽  
Experimental Approach ◽  
Model Tests ◽  
Ship Hull ◽  
Experimental Results ◽  
Shallow Waters ◽  
Towing Tank ◽  
Ship Model

One of the phenomena restricting the tanker navigation in shallow waters is reduction of under keel clearance in the terms of sinkage and dynamic trim that is called squatting. According to the complexity of flow around ship hull, one of the best methods to predict the ship squat is experimental approach based on model tests in the towing tank. In this study model tests for tanker ship model had been held in the towing tank and squat of the model are measured and analyzed. Based on experimental results suitable formulae for prediction of these types of ship squat in fairways are obtained.

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