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Experimental and Numerical Investigations of the Hydrodynamic Characteristics, Twine Deformation, and Flow Field Around the Netting Structure Composed of Two Types of Twine Materials for Midwater Trawls

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Journal of Ocean University of China 2021年第5期20卷 1215-1235页

作者： THIERRY Bruno Nyatchouba Nsangue TANG Hao achile njomoue pandong XU Liuxiong ZHOU Cheng HU Fuxiang College of Marine Sciences Shanghai Ocean UniversityShanghai 201306China National Engineering Research Center for Oceanic Fisheries Shanghai 201306China Key Laboratory of Oceanic Fisheries Exploration Ministry of Agriculture and Rural AffairsShanghai 201306China The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources Ministry of EducationShanghai Ocean UniversityShanghai 201306China Scientific Observing and Experimental Station of Oceanic Fishery Resources Ministry of Agriculture and Rural AffairsShanghai 201306China Laboratory E3M National High Polytechnic School of DoualaUniversity of DoualaDouala 2701Cameroon Faculty of Marine Science Tokyo University of Marine Science and TechnologyMinatoTokyo 108-8477Japan

Nettings are complex flexible structures used in various *** the hydrodynamic characteristics,de-formation,and the flow field around nettings is important to design successful fishing *** study investigated the hydrodynamic characteristics and deformation of five nettings made of polyethylene and nylon materials in different attack angles through numeri-cal simulation and physical model *** numerical model was based on the one-way coupling between computational fluid dynamics(CFD)and large deflection nonlinear structural ***-Stokes equations were solved using the finite volume ap-proach,the flow was described using the k-ωshear stress turbulent model,and the large deflection structural dynamic equation was derived using a finite element approach to understand the netting deformation and nodal *** porous media model was chosen to model the nettings in the CFD *** data were compared with the experimental results of the physical model to validate the numerical *** showed that the numerical data were compatible with the experimental data with an average relative error of 2.34%,3.40%,6.50%,and 5.80%in the normal drag coefficients,parallel drag coefficients,inclined drag coefficients,and inclined lift coefficients,*** hydrodynamic forces of the polyethylene and nylon nettings decreased by approxi-mately 52.56%and 66.66%,respectively,with decreasing net *** drag and lift coefficients of the nylon netting were appro-ximately 17.15%and 6.72%lower than those of the polyethylene netting.A spatial development of turbulent flow occurred around the netting because of the netting ***,the flow velocity reduction downstream from the netting in the wake region in-creased with increasing attack angle and net *** addition,the deformation,stress,and strain on each netting increased with in-creasing solidity ratio.

关键词： netting k-ωshear stress turbulent(SST)model porous media model large deflection nonlinear structural model hydrodynamic characteristics

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Identifying the turbulent flow developing inside and around the bottom trawl by Electromagnetic Current Velocity Meter approach in the flume tank

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Journal of Hydrodynamics 2021年第3期33卷 636-656页

作者： Nyatchouba Nsangue Bruno Thierry Hao Tang Liu-xiong Xu Fuxiang Hu Xinxing You Micah Adekunle David njomoue pandong Achille College of Marine Sciences Shanghai Ocean UniversityShanghai201306China National Engineering Research Center for Oceanic Fisheries Shanghai201306China Key Laboratory of Oceanic Fisheries Exploration Ministry of Agriculture and Rural AffairsShanghai201306China The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources Shanghai Ocean UniversityMinistry of EducationShanghai201306China Scientific Observing and Experimental Station of Oceanic Fishery Resources Ministry of Agriculture and Rural AffairsShanghai201306China Department of Marine Biosciences Tokyo University of Marine Science and TechnologyMinatoTokyoJapan College of Fisheries and Life Sciences Shanghai Ocean UniversityShanghai201306China Faculty of Industrial Engineering University of DoualaDoualaCameroon

The Knowledge of turbulent flow developing inside and around the bottom trawl net is of great importance not only for improving the hydrodynamic performance of the gear but also for the selectivity via the fish response,such as the herding response or escape *** 3-D Electromagnetic Current Velocity Meter(ECVM)measurements were performed to investigate the effect of turbulent flow on the bottom trawl net performance and to analyze the turbulence intensity and velocity ratio inside and around different parts of the trawl *** orthogonal decomposition(POD)method was applied in order to extract the phase averaged mean velocity field of turbulent flow from each available ECVM instantaneous *** results demonstrated the existence of turbulence flow,consisting of turbulent boundary layer flow and the turbulence due to the trawl wake developing all inside and around the bottom trawl *** input streamwise velocity results in faster trawl movement and a significant turbulent *** maximum turbulence intensity inside and around trawl wing,square part,first belly,second belly,third belly,cod-end is 0.95%,1.34%,3.40%,4.10%,4.25%and 3.80%,*** was found that the mean velocity field in a turbulent flow inside and around trawl net cod-end recovered on the average was~77.58%of the input streamwise *** is~12.92%,~13.07%,~11.40%,~13.00%and~0.45%less than that inside and around trawl wing,square part,first belly,second belly,and third belly of the bottom trawl net,*** turbulent flow behavior depends strongly on the structure oscillation,input streamwise velocity and,porosity of the net *** is necessary to take into account the velocity reduction inside and around a different part of the trawl net to improve the entire drag force determination,cod-end design,and further selectivity control of the fishing gear.

关键词： Hydrodynamic bottom trawl net turbulent flow Electromagnetic Current Velocity Meter(ECVM) turbulence intensity proper orthogonal decomposition(POD)

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Assessment of the Selective Properties and Optimization of Mesh Size of Pelagic Trawl Codends, Used for Fishing Mackerel (Trachurus Spp) in the Gulf of Guinea

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Open Journal of Marine Science 2013年第2期3卷 103-111页

作者： njomoue pandong Achille Ebeku Ngomo Christopher Tcham Leopold Department of Fisheries Faculty of Industrial Engineering University of Douala Douala Cameroon

Over the past few decades, it has become widely recognized that the management strategies of world fisheries must ensure sustainability of target species. The intervening years have seen many improvements to the concept of gear selectivity and methods for measuring the selectivity of fishing towed gears. Improved understanding of the principles of the selection of fish by gears has changed the list of parameters which are known to have a significant effect upon selection. The recent development of new mathematical models and the increased availability of powerful computers have resulted in improvements in the analysis procedures for the data produced to measure a gear’s selectivity. The catch of mackerel in the gulfofGuineahas steeply declined during the last two decades, and resource management is clearly required. Therefore, the need for evaluation of trawl codends used in this fishery and the potential improvements to their selectivity are of prime importance. In this paper, we use semi-empirical models to define selective properties of pelagic trawl codends targeting black mackerel (Trachurus spp) in theGulfofGuinea. These properties are determined using the experimental and theoretical methods of assessing the parameters of the selectivity curve, and by plotting the curve. Selection parameters were obtained by fitting a logistic equation using a maximum likelihood method. Trawl codend selectivity is estimated for 17 internal diamond mesh sizes in the range 47 - 79 mm. Using the basic selectivity equations, we determine the needed mesh size A = 58 mm for fishing mackerel in the gulf of Guinea. This nominal mesh size gives room for nj = 0.1 catch of juveniles, which not exceeds the allowable proportion [nj] = 0.1. To provide resource conservation, there is the need to make amendments in the fishery regulations for more rational exploitation of mackerel stoks, because the currently use nominal mesh size A = 56 mm is rather unselective.

关键词： Codend Selectivity Mesh Size Gulf of Guinea Selectivity Models

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Diagnosis of Thermal Overload and Power Losses in Boat Yang 1’s CAT 3408 Marine Diesel Engine from Used Oil and Coolant Analysis

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Modern Mechanical Engineering 2022年第3期12卷 74-82页

作者： Maurice Vanlie Kontchou Théophile Emakoua Achille njomoue pandong Department of Maritime and Port Engineering National Higher Polytechnic School of Douala University of Douala Douala Cameroon

In the design of the CAT 3408 engine, the Low Temperature (BT) circuits used to cool the engine lubricating oil and the charge air and the High Temperature (HT) circuits for cooling the cylinder liners, cylinder heads and body of turbofans are mainly used to cool the engine, so that it works properly. This work, based on the analysis carried out, to determine the lubrication compliance of the Yacco VX 100 - SAE 15 W-40 oil and that of the Camwater water used in the engine of the Boat Yang 1 by carrying out a series of conventional tests such as that: the density, the viscosity, the viscosity index, the flash point, the density, the sulphate center content, the water content, the total acidity index (TAN), total basic number (TBN) and pour point for the oil case and pH, hardness, sodium chloride content [NaCl], sodium sulphate content [NaSO4] for the water case which will be compared to the specified requirements to determine whether compliance is achieved for each of these characteristics. The results of the oil and water samples taken from the engine after use show that the used oil gives a specific gravity of 0.8822, a viscosity (at 40°C) of 92.29 mm2/s, a viscosity (at 100°C) of 13.99 mm2/s, a viscosity index (VI) of 155.39, a pour point -21°C, a Flash Point (VO) 215°C, a Sulfated ash content of 18%, a density 881.5 kg/m3, a total basic number (TBN) of 12.60 mgKOH/g, a Total Acid Index (TAN) of 3.096 mgKOH/g, a Water Content of 1.8 % and the water used gives a pH of 6.00, a hardness of 3.2 french degrees, a sodium chloride content [NaCl] of 0.468 mg/L, and a calcium sulphate content [CaSO4] of 2.38345 mg/L. the results of the water content and content of sulfated centers justify the thermal overload and power losses in the marine diesel engine CAT 3408 of the boat Yang 1 because of their values which are not in conformity with the standards.

关键词： Reporting Reasons Thermal Overload Power Losses

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Hydrodynamic Performance of a Newly-Designed Pelagic and Demersal Trawls Using Physical Modeling and Analytical Methods for Cameroonian Industrial Fisheries

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Open Journal of Marine Science 2023年第3期13卷 41-65页

作者： Tcham Leopold Vanlie Maurice Kontchou Nyatchouba Nsangue Bruno Thierry Abdou Njifenjou njomoue pandong Achille Laboratory of Energy Materials Modeling and Method (E3M) National Higher Polytechnic School of Douala University of Douala Douala Cameroon College of Marine Science Shanghai Ocean University Shanghai China

This study proposed the newly-designed Pelagic and demersal trawls for the fishing vessels operating in Cameroonian waters in pelagic and demersal fishing grounds. The engineering performances of both trawls were investigated using physical modelling method and analytical method based on the predicted equations. In a flume tank, a series of physical model tests based on Tauti’s law were performed to investigate the hydrodynamic and geometrical performances of both trawls and to assess the applicability of the analytical methods based on predicted equations. The results showed that in model scale, the working towing speed and door spread for the pelagic trawl were 3.5 knots and 1.85 m, respectively, and for the bottom trawl net they were 4.0 knots and 1.8 m. At that speed and door spread, the drag force, net opening height, and wing-end spread of the pelagic model trawl were 36.73 N, 0.89 m, and 0.86 m, respectively, and the swept area was 0.76 m2. Bottom trawl speed and door spread were 30.43 N, 0.38 m, and 0.45 m, respectively, and the swept area was 0.25 m2. The maximum difference between the experimental and analytical results of hydrodynamic performances was less than 56.22% and 41.45%, respectively, for pelagic and bottom trawls, the results of the geometrical performances obtained using predicted equations were close to the experimental results in the flume tank with a maximum relative error less than 12.85%. The newly developed pelagic and bottom trawls had advanced engineering performance for high catch efficiency and selectivity and could be used in commercial fishing operations in Cameroonian waters.

关键词： Cameroonian Waters Pelagic Trawl Bottom Trawl Engineering Performances Physical Model Test Analytical Methods Formatting

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Ichthyofaunic Inventory and Fish Landings of Lom Pangar Hydropower Dam Reservoir in the Eastern Region of Cameroon

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Open Journal of Marine Science 2020年第4期10卷 245-259页

作者： Achille njomoue pandong Bruno Thierry Nyatchouba Nsangue Ekmon Mbangue N’Souvi Kodjo Maurice Vanlie Kontchou Asser Yoke Léopold Tcham Dieudonné Essola Micah Adekunle David Laboratory E3M National High Polytechnic School of Douala University of Douala Douala Cameroon College of Marine Science Shanghai Ocean University Shanghai China College of Economics and Management Shanghai Ocean University Shanghai China Netherlands Development Organisation SNV Yaounde Cameroon College of Fisheries and Life Science Shanghai Ocean University Shanghai China

The Lom Pangar hydroelectric dam project located in the eastern region of Cameroon was implemented by Electricity Development Corporation (EDC). The impoundment of the Lom Pangar dam created a large reservoir with an area ~590 km2 and a useful storage capacity ~6 billion m3. Thereby, this impoundment has created favourable conditions for the proliferation of fishery resources. However, a fisheries assessment study based on fishing activities is essential to attain reliable information for implementing a management plan to achieve rational and sustainable exploitation. This study was carried out on the ichtyofaunic inventory and the assessment of fish landings in Lom Pangar hydroelectric dam reservoir from April 2016 to September 30, 2016. Three main groups of fishing gear have been identified, among which gillnets, traps and longlines occupy major fishing activities. Indeed, the spatial and landing sites surveies were conducted on species composition, size composition, and quantities of fish landed during the study period. Moreover, 37 species of fish divided into 16 families were found in seven different selected fish landing sites. Carp (Cyprinus carpio) was the major fish species abundantly caught by these fishing gears which accounted for 81.60% of the total catch, and the least species was sardine (Sardinella aurita). A total of 623,229 Kg of fish were landed which were dominated by those of the Wami landing site with 480,773 Kg representing 76.96% of the total landed catches. The smallest species caught was the white carp (7 cm) while the longest one was the catfish (71 cm). In addition, the species of fish in the breeding season are carp, catfish, viper fish and red tail.

关键词： Artisanal Fishing Gears Ictyofaunal Inventory Lom Pangar Hydropower Dam

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