Numerical Analysis of the Motion of a Flexible Hose Net Used for Hauling a Box Chamber Net in Set Net Fishery

2012 ◽  
Author(s):  
Daisuke Kitazawa ◽  
Yoichi Mizukami ◽  
Yoshio Hirai
Keyword(s):  
Numerical Analysis ◽  
Drag Force ◽  
Early Morning ◽  
Experimental Result ◽  
Water Tank ◽  
Three Dimension ◽  
Flexible Hose ◽  
Middle Point ◽  
Simple Method ◽  
Time Changes

A set net fishery is one of the most popular fishing methods and has a history of a few hundred years in Japan. The hauling operation of a box chamber net is one of the essential works for fishermen to harvest fishes, not losing and damaging them. However, the current net-hauling system requires many personnel powers with danger works in early morning. The present study proposes a flexible hose net for hauling a box chamber net in an automated way. Flexible hoses are arranged like a brick form and installed in the bottom of the box chamber net. Compressed air is injected into flexible hoses at one edge of the hose net. The water tank models of the set net and the hose net are made based on the similarity law of Tauchi, while the Reynolds dependency is not taken into account. The hose net rose like an S shape to drive fishes into the smaller domain gradually. Then a simple method of numerical analysis is represented to estimate the formation and the tension of the flexible hose net. For simplicity, the formation of a flexible hose net in the direction normal to air injection is uniform. The hose net is assumed to be flexible with and without air inside the hoses. Hence the hose net is approximated by a flexible cable. A maximal tension of the flexible hose net is the key parameter for its design. The tension is expected to be maximal at the middle point on the flexible hose net when the flexible hose net obtains the half of the total buoyancy. Therefore, the formation of the flexible hose net at this time is analyzed in comparison with the experimental result. The projected area, drag coefficient, current velocity, and the tension at the origin (pretension) are varied to investigate the sensitivity of these parameters to the formation of the flexible hose net. When the parameters related to the drag force on the fish cage were varied, little difference could be found among the analyzed results. The drag force on the flexible hose net exerts little effect on its formation, and is overwhelmed by the effects of gravity and buoyancy. The formation of the hose net is sensitive to the tension at the origin. As future studies, the tension will be measured at several points on the hose net in water tank testing by more precise tank model considering the stiffness of the hose and the Reynolds dependency. Then the numerical model will be expanded to three-dimension to take the time changes in the formation of the flexible hoses and drag force into account.

Development of the Fish Cage Installed in Variable Depths

2012 ◽  
Author(s):  
Hiroki Shimizu ◽  
Daisuke Kitazawa ◽  
Yoichi Mizukami
Keyword(s):  
Numerical Analysis ◽  
Drag Force ◽  
Experimental Result ◽  
Water Current ◽  
Maintenance Cost ◽  
Mooring System ◽  
Water Tank ◽  
Exposed Area ◽  
Balance Of Forces ◽  
Open Ocean Aquaculture

Aquaculture is expected to play a key role in the increase in fishery production in the future. Because of environmental and coastal utilization issues, however, it is necessary for us to operate cultivation in exposed area for more fishery production, where the fish cage and its mooring system face severe environmental condition such as typhoon. In that area the fish cage should be submerged to protect it from high waves since the influence of waves is reduced in deeper water. Nevertheless, the technologies for open ocean aquaculture are still in the phase of being developed. For example, in general operating systems, a fish cage is floated or submerged on the basis of the framework which is fixed by buoys and anchors. In the exposed area, however, buoys are broken by waves, resulting in the high maintenance cost. Our research aims at creating the new mooring system of a fish cage. The fish cage is moored without the framework in various depths. Buoys can be submerged so that the maintenance cost of the mooring system must be reduced. The feasibility of the mooring system is examined by smaller-scale water tank testing and simple numerical analysis. First the behavior of the mooring system in still water was examined by both numerical analysis and tank model testing. As a result, the fish cage can be submerged at an arbitrary depth only by changing the ratio of the buoyancy to the weight of the fish cage. Then, using a new model of a fish cage, towing test was carried out to estimate the drag force. The drag force is proportional to the 1.5 powered velocity of water current, which is different from the second powered velocity usually used in numerical analysis. This discrepancy may be attributed to the lack of measured data. It should be also noted change in the attacking angle of water current can influence the drag force. Finally, towing test of the mooring system was carried out at the various towing speeds to examine the change in the geometrical formation of the system. At the higher towing speed fish cage is more submerged due to the increase of drag force. In addition, the fish cage begins inclining just after towing. The drag force must vary since the projected area changes due to the inclination of the fish cage and to the deformation of the net. However, the forces on the fish cage are balanced again so that the geometrical formation becomes stable. As future studies, the experimental result will be compared with the analytical one, in which the effect of drag force will be added to the balance of forces on the fish cage. The water tank has a wave maker, so waves will be added to the water current since wave-induced forces work on the fish cage submerged near water surface.

Numerical Analysis for Stability and Self-Excited Oscillation in Collapsible Tube Flow

1998 ◽  
Vol 120 (4) ◽  
pp. 468-475 ◽  
Author(s):  
S. Hayashi ◽  
T. Hayase ◽  
H. Kawamura
Keyword(s):  
Numerical Analysis ◽  
Flow Separation ◽  
Numerical Procedure ◽  
The Self ◽  
Lumped Parameter Model ◽  
Experimental Result ◽  
Tube Flow ◽  
Collapsible Tube ◽  
Simple Method ◽  
Excited Oscillation

This paper describes numerical analysis of collapsible tube flow based on the one-dimensional distributed parameter model of Hayashi. In the present model the effect of flow separation at the collapsed part is replaced with simple viscous friction along the tube, so no ad-hoc modeling for flow separation in former studies is required. A stable semi-implicit numerical procedure based on the SIMPLE method is developed for the problem of flow and tube interaction. The numerical result for a characteristic self-excited oscillation agrees qualitatively with the experimental result. Nonlinear stability of the steady state dependent on the amplitude of the disturbance is numerically investigated and the result is compared with the linear stability analysis based on the former lumped parameter model. Finally, initiation of the self-excited oscillation is examined by applying the initial disturbance at the upstream end of the tube. The disturbance propagates in the downstream direction and is amplifled to the self-excited oscillation.

Water-tank experiment and static numerical analysis of the mooring system of a controllable depth cage

2020 ◽  
Vol 91 ◽  
pp. 102118
Author(s):  
Junbo Zhang ◽  
Hiroki Shimizu ◽  
Hirotaka Nakashima ◽  
Yoichi Mizukami ◽  
Takero Yoshida ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Mooring System ◽  
Water Tank ◽  
Tank Experiment ◽  
Water Tank Experiment

Nonlinear Numerical Analysis of Transfer Column in SRC-RC Hybrid Structure

2014 ◽  
Vol 578-579 ◽  
pp. 936-939 ◽  
Author(s):  
Qian Qian Sun ◽  
Yun Zou ◽  
Qiang Wang
Keyword(s):  
Numerical Analysis ◽  
Axial Load ◽  
Load Ratio ◽  
Hybrid Structure ◽  
Area Ratio ◽  
Experimental Result ◽  
Finite Element Software ◽  
Axial Load Ratio ◽  
Hysteretic Performance ◽  
Extension Length

Nonlinear numerical analysis of the stress performance of SRC-RC transfer columns was carried out in this paper with the finite element software of ABAQUS. Compered with the experimental result , numerical analysis result are found to be reasonable.Then the influence of factors such as extension length of shape steel , area ratio of shape steel and axial-load ratio were contrastively analyzed . The results show that extension length of shape steel and the area ratio of shape steel have a greater influence on the bearing capacity and the hysteretic performance of transfer column ,but axial-load ratio has less influence .

Behavior of Bubble in Small Water Tank Used for Food Processing Using Underwater Shock Wave

2011 ◽  
Vol 673 ◽  
pp. 225-230 ◽  
Author(s):  
Hideki Hamashima ◽  
Manabu Shibuta ◽  
Shigeru Itoh
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Food Processing ◽  
High Speed ◽  
Underwater Explosion ◽  
Video Camera ◽  
Experimental Result ◽  
Water Tank ◽  
Underwater Shock Wave ◽  
Small Water

The food processing technology using a shock wave can prevent deterioration of the food by heat because it can process food in a short time. Generally, since the shock wave used for food processing is generated by underwater explosion, the load of a shock wave to the food becomes very complicated. Therefore, in order to process safely, it is important to clarify the behaviors of the shock wave and the bubble pulse generated by underwater explosion. In this research, in order to investigate the behavior of the shock wave in the water tank used for food processing, the optical observation experiment and the numerical simulation were performed. In the experiment, the shock wave generated by underwater explosion was observed with the high-speed video camera. The numerical simulation about the behavior of bubble pulse was performed using analysis software LS-DYNA. Comparing and examining were performed about the experimental result and the numerical simulation result. The result of the numerical simulation about the behavior of the shock wave generated by underwater explosion and the shock wave generated by the bubble pulse and the bubble pulse was well in agreement with the experimental result.

The application of resonance enhanced multiphoton ionization to the detection of hydrogen atoms during the oscillatory combustion of hydrogen

1991 ◽  
Vol 434 (1891) ◽  
pp. 399-412 ◽  
Keyword(s):  
Numerical Analysis ◽  
Flow Reactor ◽  
Multiphoton Ionization ◽  
Laser Wavelength ◽  
Time Profile ◽  
Experimental Result ◽  
Oh Radicals ◽  
Hydrogen Atoms ◽  
Experimental Conditions ◽  
Concentration Time

The relative concentrations of hydrogen atoms were measured during the oscillatory ignition of hydrogen in a well stirred flow reactor. Comparisons were made with the experimental concentration—time profiles of the hydroxyl radical obtained previously under similar experimental conditions. The predicted concentration profiles obtained from numerical analysis of a thermokinetic model were also compared with the experimental results. Experiments were performed in a 600 cm 3 Pyrex glass, jet-stirred reactor with the reactants, 2H 2 + O 2 , at a total pressure of 16 Torr ( ca . 2132.8 Pa) and at a vessel temperature of 753 K. The mean residence time was 1.2 s. Oscillatory ignition was established at a period of 3 s in which high radical concentrations were attained and in which the temperature rise was almost adiabatic. The concentration-time profile of hydrogen atoms was obtained by a resonance enhanced multiphoton ionization (rempi) which was induced by a laser pulse at energies in the vicinity of 364 nm, with ion collection at a stainless steel probe inserted into the reactor. Supplementary studies were made to characterize the signals and to identify effects of the probe within the reaction volume. A measurement of the relative concentrations of hydrogen atoms was obtained from an integration of the area of the rempi spectrum determined over the laser wavelength range 363.8-364.6 nm. The spectrum was measured at successive times in the oscillatory cycle by imposing a variable delay on the laser firing signal. The results show that, during oscillatory ignition, the maximum concentration of hydrogen atoms was reached and a sharp decay was already well advanced before that of the hydroxyl radicals was attained. The numerical analysis was in very good quantitative accord with this experimental result. The phase difference of the cyclic variation in the H atoms relative to that of OH radicals is a key feature of the kinetic mechanisms which control the oscillatory oxidation of hydrogen.

Influence of Design Parameters of Highway on the Deformation

2012 ◽  
Vol 178-181 ◽  
pp. 1658-1662
Author(s):  
Yan Mei Zhang ◽  
Xu Dong Zhang
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Traffic Load ◽  
Design Parameters ◽  
Three Dimension ◽  
Vertical Deformation ◽  
Irregularity Index ◽  
Surface Stiffness

Based on the geometry irregularity of pavement, an expression of the traffic load was put forward. The influence law of design parameters of each part of highway and pavement geometry irregularity on vertical deformation of highway was discussed by the three-dimension finite element numerical analysis. The research shows that the vertical deformation range of highway under the action of traffic load is generally semi-circular; the influence of surface stiffness on vertical deformation is different in different horizontal positions of surface; the influence of subgrade stiffness and foundation stiffness on vertical deformation is remarkable, but that of course stiffness is small; the rational matching of all parts of highway can effectively reduce the vertical deformation; with the increase of geometric irregularity index, the vertical deformation increases significantly.

scholarly journals Bidirectional Underwater Visible Light Communication

2018 ◽  
Vol 8 (6) ◽  
pp. 5203
Author(s):  
Arsyad Ramadhan Darlis ◽  
Andre Widura ◽  
Muhamad Rifan Andrian
Keyword(s):  
Visible Light ◽  
Visible Light Communication ◽  
Experimental Result ◽  
Color Filter ◽  
Optical Channel ◽  
Water Tank ◽  
Underwater Environment ◽  
Information Signal ◽  
Blue Wavelength ◽  
The One

In this paper, a novel bidirectional underwater visible light communication (BiUVLC) is proposed. The VLC transmitter transmits an information signal using the one of RGB LED through the water tank that represents an underwater environment and then is received by VLC receiver via a color filter. The color LEDs and color filters are utilized in bidirectional systems. The single link is created by a LED on the transmitter and the color filter on the receiver with the same color which represents a single wavelength. The performance of the proposed BiUVLC system was evaluated via implementations. The experimental result shows that the transmitted signal undergoes attenuation over the underwater optical channel and the pair of the blue wavelength in link 1 and the green wavelength in link 2 have the best performance than the other wavelength pair. In the crosstalk measurement, the red wavelength color is the worst in the underwater environment.

scholarly journals Numerical analysis of the flow around a cylinder for the perspective of correlations of the drag coefficient of the ship’s hulls

2019 ◽  
Vol XXII (2) ◽  
pp. 256-267
Author(s):  
Baracu T.
Keyword(s):  
Numerical Analysis ◽  
Drag Force ◽  
Complex Shape ◽  
Complex Geometries ◽  
Flow Properties ◽  
Flat Plates ◽  
Hydrodynamic Properties ◽  
Flow Around A Cylinder ◽  
Flow Around Cylinder ◽  
External Flows

The flow around cylinder open the path for studying more complex shape bodies like the ship’s hulls. The hydrodynamic properties of the ship’s hulls can be decomposed as combinations of the flow properties of simpler bodies like flat plates, cylinders, ellipses, spheres and ellipsoids. The aim of this study is to describe the flow around a cylinder based on simulations with platforms like Comsol and Ansys that further can be compared with experimental and analytical results. The drag force caused by the flow around cylinders can be combined with the drag force of simple elements like flat plates, ellipses in order to correlate with the drag force of a specific hull of ship. Cylinder is a case that offers with its simplicity the possibility to check the results in all three ways: analytical, computational and experimental. An exhaustive analysis of this shape offers a beginning path for generalizing the external flows like the application of the superposition theory for complex geometries.

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