Numerical Investigation of the Flow Through and Around a Net Cage

2009 ◽  
Author(s):  
Kyujin Shim ◽  
Pascal Klebert ◽  
Arne Fredheim
Keyword(s):  
Flow Pattern ◽  
Numerical Approach ◽  
Large Structures ◽  
Lower Porosity ◽  
Oxygenated Water ◽  
Flow Through ◽  
Net Cage ◽  
Net Cages ◽  
Vertical Cylinders ◽  
The Impact

Structure and design of fish cages can be improved by the knowledge of the flow pattern around and inside the net cages. To address this problem, commercially available computational fluid dynamics (CFD) software is used to analyze this problem by calculating the drag and the flow velocity distribution around cylinders with different porosities. The results of these simulations are compared with the data from experiments which have been previously published. Aquaculture cages are very large structures that consist mainly of netting, which can be approximated by small cylinders connected at knots. But due to the large number of these cylinders (millions for a single salmon farming cage), it is computationally expensive to model the exact geometry. Bio fouling is another factor which is of particular interest as fouled nets (lower porosity) can significantly reduce flow of well-oxygenated water reaching the fish during normal rearing conditions. Therefore the numerical approach used to simulate the flow through and around the net cage is to consider it as a circular cylinder with a porous jump boundary. Drag coefficient and flow pattern are compared with available experimental data. Vertical cylinders are used for this study. Different porosities have been used for the simulations as for the experiments (0%, 75%, 82% and 90% open area) in order to simulate the impact of the fouling on the load of the net structures and the flushing of the cage. The results show that a porous jump with a pressure drop proportional to velocity squared has the best agreement with measured data.

scholarly journals The Impact of Floods on Fish Cultivation Business in Floating Net Cages in Sungai Alang Village, Karang Intan District, Banjar Regency, South Kalimantan

2021 ◽  
Vol 04 (08) ◽  
Author(s):  
Irma Febrianty ◽  
Keyword(s):  
Fish Farming ◽  
Survey Method ◽  
The Social ◽  
Business Analysis ◽  
Flood Disasters ◽  
University Cooperation ◽  
Net Cage ◽  
Net Cages ◽  
The Impact ◽  
Cage Fish

The flood that hit Sungai Alang Village resulted in many floating net cages being lost in the flood, so many farmers lost their cages and caused losses for fish farmers. The aims of the study were to analyze: 1. The economic impact of floating net cage fish cultivators' losses. 2. The impact of social losses experienced by fish farmers. This study uses a survey method, the analysis used is business analysis and descriptive. The results of the analysis of the impact of flooding on fish cultivation in floating net cages in Sungai Alang village: 1. The economic impacts that occur are the loss of cages, loss of fish and damage to nets which result in farmers' losses. 2. The social impacts that occur are affecting the education of family members who continue to university cooperation from the community in dealing with flood disasters, changes in business due to flooding from fish farming in cages to fishing, gardening, cutting sap, raising chickens and selling vegetable.

Wave Induced Deformation and Stress Responses in HDPE Circular Net Cage: A Numerical Approach

2012 ◽  
Vol 217-219 ◽  
pp. 2299-2303
Author(s):  
Jian Hang Du ◽  
Zhen He ◽  
Feng Lin Yan ◽  
Guo Yan Yu
Keyword(s):  
Stress Responses ◽  
Peak Stress ◽  
Numerical Approach ◽  
Wave Forces ◽  
Response Characteristics ◽  
Simulation Testing ◽  
Net Cage ◽  
Dynamics Response ◽  
Net Cages ◽  
Wave Induced

A 3D numerical model was developed to analyze the deformation and stress characteristics of HDPE material circular net cage exposed to waves, using the finite element method (FEM). The total wave forces acting on the structure were evaluated with method combining analytical and numerical, and served as boundary conditions during the simulation. Testing cases were performed eventually based on the actual conditions in Zhanjiang bay. The results show that wave height is an important factor that affects the dynamics response characteristics of net cages as well as the working conditions of the cages in sea environment, and the peak stress of the flotation structure always occurs at the mooring points. We also suggest that the net cages that constructed inside Zhanjiang Bay may not fail even during the storm process when in normal working condition.

scholarly journals TINJAUAN YURIDIS TERHADAP PERJANJIAN YANG DILARANGDALAM UNDANG-UNDANG NOMOR 5 TAHUN 1999 TENTANG LARANGAN PRAKTEK MONOPOLI DAN PERSAINGAN USAHA TIDAK SEHAT YANG DILAKUKAN OLEH PELAKU USAHA KERAMBA JARING APUNGDI HARANGGAOLHORISON KABUPATEN SIMALUNGUN

2020 ◽  
Vol 1 (2) ◽  
pp. 8-21
Author(s):  
Roida Nababan ◽  
Jeremia Saragih
Keyword(s):  
Vertical Integration ◽  
Field Research ◽  
Secondary Data ◽  
Primary Data ◽  
Literature Study ◽  
Literature Research ◽  
Net Cage ◽  
Net Cages ◽  
The Impact ◽  
Cage Fish

This study aims to analyze the forms of agreement prohibited in Law Number 5 of 1999 concerning the Prohibition of Monopolistic Practices and Unfair Business Competition carried out by floating net cage business actors in Haranggaol Horison, Simalungun Regency. This study uses a juridical empirical and normative juridical approach, through field research and literature research to obtain primary data and secondary data. Literature study is carried out on statutory regulations and other literature and field research is carried out by interviewing business actors of floating net cages in Haranggaol Horison, Simalungun Regency. The data obtained were then analyzed using a quantitative approach and described by analytical descriptive. The results of the study concluded that the forms of agreements that are prohibited under Law 5 of 1999 carried out by business actors in Haranggaol Horison include oligopoly, price fixing agreements, oligopsony, and vertical integration. To prevent the form of a prohibited agreement, it is necessary to establish a cooperative for floating net cage fish business actors to supervise business competition, direct and mitigate the impact of unfair business competition.  

Upward Vertical Two-Phase Flow Through an Annulus—Part II: Modeling Bubble, Slug, and Annular Flow

1992 ◽  
Vol 114 (1) ◽  
pp. 14-30 ◽  
Author(s):  
E. F. Caetano ◽  
O. Shoham ◽  
J. P. Brill
Keyword(s):  
Flow Pattern ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubble Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through ◽  
Physical Phenomena ◽  
Good Agreement

Mechanistic models have been developed for each of the existing two-phase flow patterns in an annulus, namely bubble flow, dispersed bubble flow, slug flow, and annular flow. These models are based on two-phase flow physical phenomena and incorporate annulus characteristics such as casing and tubing diameters and degree of eccentricity. The models also apply the new predictive means for friction factor and Taylor bubble rise velocity presented in Part I. Given a set of flow conditions, the existing flow pattern in the system can be predicted. The developed models are applied next for predicting the flow behavior, including the average volumetric liquid holdup and the average total pressure gradient for the existing flow pattern. In general, good agreement was observed between the experimental data and model predictions.

scholarly journals Influence of Age on the Technical Wear of Tenement Houses

2020 ◽  
Vol 11 (1) ◽  
pp. 297
Author(s):  
Jarosław Konior ◽  
Marek Sawicki ◽  
Mariusz Szóstak
Keyword(s):  
Residential Buildings ◽  
Residential Building ◽  
Numerical Approach ◽  
Technical Condition ◽  
Visual Methods ◽  
Secondary Importance ◽  
Building Maintenance ◽  
Technical Maintenance ◽  
Traditional Construction ◽  
The Impact

The research presented in the article, which includes methods, models, and conclusions, contains synthetic and analytical model solutions concerning the problems of the technical maintenance and wear of residential buildings with a traditional construction. The cause and effect relationships between the occurrence of damage in the elements of tenement houses (treated as proof of their maintenance conditions), and the size of the technical wear of these elements were determined using a representative and purposefully selected sample of 102 residential buildings erected during the second half of the nineteenth and early twentieth centuries in Wroclaw’s “Downtown” district. Quantitative damage analysis, which was carried out using empirical (visual) methods of assessing the technical condition of a building, indicates the type and size of damage to the building’s elements that are characteristic for the relevant maintenance conditions. Research concerning the cause–effect relationships (“damage–technical wear”) in observed states allows for a numerical approach to the impact of building maintenance conditions on the degree of the technical wear of its components. The maintenance and exploitation conditions determine the degree of the technical wear of the elements of an old residential building. The exploitation condition of these buildings is manifested by damage to elements caused by water and moisture penetration, which is especially important for poorly maintained buildings. The article shows that the age of the elements of an old residential building with a traditional construction is of secondary importance in the process of the intensity of losing its serviceability value. It was calculated that no more than 30% of the damage of building components is explained by the passage of time, and it is therefore not age that determines the course of the technical wear of the elements of the analyzed tenement houses.

The Impact of Urbanization on Air Flow Pattern: The Case of Rio de Janeiro

2014 ◽  
Vol 12 (9) ◽  
pp. 908-916 ◽  
Author(s):  
Marilia Ramalho Fontenelle ◽  
Sylvie Lorente ◽  
Leopoldo Eurico Gonçalves Bastos
Keyword(s):  
Flow Pattern ◽  
Rio De Janeiro ◽  
Air Flow ◽  
Impact Of Urbanization ◽  
The Impact

scholarly journals The Impact of Microstructure Geometry on the Mass Transport in Artificial Pores: A Numerical Approach

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Matthias Galinsky ◽  
Ulf Sénéchal ◽  
Cornelia Breitkopf
Keyword(s):  
Mass Transport ◽  
Porous Materials ◽  
Effective Diffusion ◽  
Direct Simulation Monte Carlo ◽  
Numerical Approach ◽  
Porous System ◽  
Length Scales ◽  
General Evaluation ◽  
Pulse Experiment ◽  
The Impact

The microstructure of porous materials used in heterogeneous catalysis determines the mass transport inside networks, which may vary over many length scales. The theoretical prediction of mass transport phenomena in porous materials, however, is incomplete and is still not completely understood. Therefore, experimental data for every specific porous system is needed. One possible experimental technique for characterizing the mass transport in such pore networks is pulse experiments. The general evaluation of experimental outcomes of these techniques follows the solution of Fick’s second law where an integral and effective diffusion coefficient is recognized. However, a detailed local understanding of diffusion and sorption processes remains a challenge. As there is lack of proved models covering different length scales, existing classical concepts need to be evaluated with respect to their ability to reflect local geometries on the nanometer level. In this study, DSMC (Direct Simulation Monte Carlo) models were used to investigate the impact of pore microstructures on the diffusion behaviour of gases. It can be understood as a virtual pulse experiment within a single pore or a combination of different pore geometries.

Predicting the Influence of Damping Devices on the Stability Margin of an Annular Combustor

2017 ◽  
Author(s):  
Max Zahn ◽  
Michael Betz ◽  
Moritz Schulze ◽  
Christoph Hirsch ◽  
Thomas Sattelmayer
Keyword(s):  
Resonance Frequency ◽  
Stability Margin ◽  
Numerical Approach ◽  
Acoustic Mode ◽  
Acoustic Properties ◽  
Azimuthal Mode ◽  
Acoustic Damping ◽  
Linearized Euler Equations ◽  
Annular Combustor ◽  
The Impact

A numerical modeling approach based on linearized Euler equations is applied to predict the linear stability of an annular combustor with and without dampers. The acoustic properties of all relevant combustor components such as damping devices, swirl burner characteristics, swirl flame dynamics, and combustor exit are individually evaluated via experimental and numerical approaches. All of the components are incorporated subsequently into the combustor model using impedances and acoustic transfer matrices to obtain an efficient procedure. This study focuses on using this approach to predict an annular combustor’s stability margin and to assess how dampers influence the modal dynamics of the first azimuthal mode. Stability predictions are successfully validated with experimental data. Different combustor components’ contributions to the acoustic damping of the entire system is also determined based on that numerical approach. Damper application in combustors can engender uncertainties in resonance frequency in the case of hot-gas ingestion. The impact of “detuned” resonators on the predicted damping rates with respect to a deviation in the resonance frequency and the eigenfrequency of the attenuated acoustic mode is therefore evaluated. The influence of dampers on the annular combustor’s stability margin is also determined.

Leakage flow analysis in the gas turbine shroud gap

2019 ◽  
Vol 91 (8) ◽  
pp. 1077-1085 ◽  
Author(s):  
Filip Wasilczuk ◽  
Pawel Flaszynski ◽  
Piotr Kaczynski ◽  
Ryszard Szwaba ◽  
Piotr Doerffer ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Gas Turbine ◽  
Mass Flow ◽  
Labyrinth Seal ◽  
Leakage Flow ◽  
Original Design ◽  
Reference Case ◽  
Content Type ◽  
Flow Through ◽  
The Impact

Purpose The purpose of the study is to measure the mass flow in the flow through the labyrinth seal of the gas turbine and compare it to the results of numerical simulation. Moreover the capability of two turbulence models to reflect the phenomenon will be assessed. The studied case will later be used as a reference case for the new, original design of flow control method to limit the leakage flow through the labyrinth seal. Design/methodology/approach Experimental measurements were conducted, measuring the mass flow and the pressure in the model of the labyrinth seal. It was compared to the results of numerical simulation performed in ANSYS/Fluent commercial code for the same geometry. Findings The precise machining of parts was identified as crucial for obtaining correct results in the experiment. The model characteristics were documented, allowing for its future use as the reference case for testing the new labyrinth seal geometry. Experimentally validated numerical model of the flow in the labyrinth seal was developed. Research limitations/implications The research studies the basic case, future research on the case with a new labyrinth seal geometry is planned. Research is conducted on simplified case without rotation and the impact of the turbine main channel. Practical implications Importance of machining accuracy up to 0.01 mm was found to be important for measuring leakage in small gaps and decision making on the optimal configuration selection. Originality/value The research is an important step in the development of original modification of the labyrinth seal, resulting in leakage reduction, by serving as a reference case.

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