Circular Tanks Research Articles

Про демпфовані усталені резонансні коливання рідини в контейнері кругового перерізу для довільних періодичних непараметричних збурень

Nonlinear modal Narimanov-Moiseev—type equations are investigated to study resonant sloshing in a vertical cylindrical tank. The tank moves periodically in the space with the forcing frequency close to the lowest natural sloshing frequency. We show that the considered sloshing problem can to within the higher-order asymptotic terms be reduced to the case of orbital tank motions in the horizontal plane. Analytical solutions of the secular system which couples the dominant amplitudes of the steady-state sloshing are analytically solved. Effect of viscous damping is accounted. The results are compared with experimental measurements conducted by diverse authors for longitudinal and circular orbital tank excitations. A parametric analysis of the amplitude curves is done to clarify how the steady-state wave regimes and their stability change versus the forcing frequency and the semi-axes ratio of the elliptic orbit. The main result consists of confirming the experimental disappearance of the counter-directed swirling wave mode (relative to the elliptic orbit direction) when passaging to the circular orbit.

Transitional fishery: a new resource for global nutritional food and medicinal security

Sea and river junctions form lagoon, sites become largely marshy land with fresh water at upper approaching river reach and brackish water towards sea. Such bays are plentiful in numbers and visited by aquatic birds during the winter seasons. Previous studies established vast possibility of harvesting biological nitrogen (N) and phosphorus (P) through aquatic bird droppings viz Guano. The vast sizes and number of such sites have huge potential for fishery with differing in quality characters which is termed as transitional fishery in the present study. Objective of the present study was to bring impetus in this new category of fishery with scientific management so as to make the venture highly efficient and responsive, and enable harnessing plentiful benefits of nutritional food and medicinal security. The transitional fishery was considered as ecosystems and various networks of ecology of land, vegetation, fish and aquatic birds were brought in a band for managing it in new pattern. Ecological lessons were hypothesized and validated by results on fishery on lagoons available in literatures. First innovative lesson was that fish adopt site in North East direction of fresh water stream, as also corroborated by honey bee comb sites on N-E side of any circular water tank’s supporting posts. The second innovative fact was to transformed terrestrial land as sites for growing highly palatable nitrogen rich organic feed for fishery. Thus, colonization and feeding become conclusive approach, as supported by past researches, as guide to fishery scientist to move steps ahead in harnessing productivity of lagoons. Thus, fresh and marine brackish water transition zones become vast resources for countries to derive prosperity and employment generations. The innovative fishery feed will be usable for other types of fisheries ie fresh water fishery as well as marine fishery.

Dietary sodium chloride effect in Nile tilapia fed with fish meal-free diets

Aim of study: To evaluate the effect of the dietary NaCl level for Nile tilapia fingerlings.Area of study: Palotina sector of Federal University of Paraná, in southern Brazil.Material and methods: An experiment was carried using 750 Nile tilapia fingerlings (4.61 ± 0.09 g) distributed in 30 1,000-L circular tanks in a completely randomized design with six treatments and five replicates. NaCl was added to extruded fish meal-free diets at 0.0, 2.5, 5.0, 7.5, 10.0 and 12.5 (g/kg). After the experimental period, fish were submitted to a 24 h-fast and weighed. All data were submitted to an analysis of variance and Tukey’s test followed by Levene’s test and regression test, using the Statistica 7.0® software package.Main results: Fish fed the NaCl-free diet presented better growth performance (p<0.05) compared to the other diets. Linear decrease effects on final weight (y = 50.1754 – 0.1672x, r2 = 0.6984), specific growth rate (y = 45.5418 – 0.1688x, r² = 0.6966), weight gain (y = 4.9465 – 0.008x; r² = 0.6886) and apparent feed conversion (y = 0.7113 + 0.0043x; r² = 0.7655) were noted. Efficiency and apparent protein retention were better in the NaCl-free diet (p<0.05). Significant differences (p<0.05) were observed for fillet fat and crude protein content. Increasing NaCl levels led to significant decreases (p<0.05) in Nile tilapia fingerling protein efficiency rates (y = 3.7804 - 0.0116x; r² = 0.6549).Research highlights: Thus, NaCl should not be included in fish meal-free diets for Nile tilapia fingerlings.

Flesh quality recovery in female rainbow trout (Oncorhynchus mykiss) after spawning

In fish rearing industry, sexual maturation results in loss of profit or at least in a delay to valorize spawning fish. Indeed, many edible fish display poor fillet quality after sexual maturation and as such cannot be processed immediately after spawning. So, a post-spawning rearing period may allow the recovering of an acceptable fillet quality. So far, flesh quality restoration after spawning has received little attention. In the present study, the evolution of technological and organoleptic qualities was investigated in diploid autumnal strain female rainbow trout (24 months of age) after spawning. Immediately after spawning, nine groups of trout (n = 25) from the same cohort were placed separately into circular tanks and fed ad libitum. Fish were then sampled at 0, 1, 2, 4, 8, 13, 16, 24, and 33 weeks after spawning (PS0, PS1, PS2, PS4, PS8, PS13, PS16, PS24, and PS33). Immature (no egg produced) female trout from the same cohort were also sampled as controls at the beginning (C0) and at the end (C33) of the experiment. Immediately after spawning, PS0 trout showed a significantly lower raw fillet yield than control (C0). Furthermore, raw fillet from these trout was less colored (lower redness a*) and presented higher lightness L* value than raw fillet from C0 trout while their fillet mechanical resistance was similar. Raw fillet yield increased after the 16th week post-spawning. The fillet lightness steadily decreased from the 4th week to the 24th week post-spawning and did not change afterwards, whereas fillet redness increased from the 8th week to the 24th week after spawning. Fillet mechanical resistance declined progressively after spawning with a significant change from the 13th week. Concerning the smoked fillet, the smoking yield of PS0 trout was significantly lower than that of C0 trout. Thereafter the smoking yield of post-spawning trout slowly increased until reaching a significantly higher value at the 24th week. The evolution of smoked fillet color and mechanical resistance after spawning was similar to that of raw fillet. At the end of the experiment, most quality parameters of PS33 trout fillet were similar to those of C33 trout. We discuss the post-spawning quality parameters recovery in three sequential phases. On the whole, our study reports that the technological and organoleptic properties of the flesh were recovered in female trout 24 weeks after spawning (≈1400 °C.day).

FREQUí­Å NCIA ALIMENTAR NA CRIAÇÃO DE JUVENIS DE SURUVI <i>Steindachneridion scriptum</i>

O presente estudo teve como objetivo determinar a frequência de alimentação para juvenis de suruvi. Foi realizado um estudo durante 60 dias para determinar os efeitos da frequência de alimentação nas medidas de crescimento, composição corporal e atividade enzimática digestiva do juvenil de suruvi (peso médio inicial: 60,19 ± 10,67 g). As unidades experimentais foram tanques circulares de 1,0 m³, estocados com 94 peixes, conectados a um sistema de recirculação. A alimentação foi oferecida durante a fase escura do fotoperí­­odo (12L:12D), sendo fornecida com os seguintes tratamentos em triplicata: FA1 = uma vez ao dia í­Â s 20:00; FA2 = duas vezes ao dia í­Â s 20:00 e 06:00 h; e FA3 = três vezes ao dia í­Â s 20:00, 01:00 e 06:00 h. Os peixes foram alimentados por uma ração comercial para peixes carní­­voros, composta por 42% de proteí­­na bruta, 11% de lipí­­dios, 20% de carboidratos e 4.380 kcal kg-1 de energia bruta em péletes de 6,0 mm. Não foram observadas diferenças significativas nas variáveis â€"¹â€"¹de crescimento, composição corporal de proteí­­nas e lipí­­dios e proteases alcalinas e atividade de lipase (p>0,05) entre os tratamentos. No entanto, houve diferenças significativas na atividade da amilase (p<0,05). Nossos resultados demonstraram que os juvenis de suruvi podem ser alimentados de forma sustentável apenas uma vez ao dia.

Analysis of land-based circular aquaculture tank flow field using computational fluid dynamics (CFD) simulation

Analysis of land-based circular aquaculture tank flow field using computational fluid dynamics (CFD) simulation

An Approximate Method of Determining the Velocity Gradient in Spiral Flocculation (Dept.C)

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Growth Performance of an Indigenous Carp Bangana dero (Hamilton) Fed on Formulated and Commercial Diets

A six month feeding experiment was conducted to compare between different diets and its effect on growth performance of an indigenous carp Bangana dero. A total of 360 uniform B. dero (average weight 4.9±0.02 g) were cultured in twelve circular fibreglass tanks @ 15 fish per tank (90 W X 64 H cm.). The fishes were fed by two commercial feeds (T1, T2), formulate feed (T3) and control feed (T4) in triplicates with 4% of body weight twice a day. Fish were maintained in well aerated water system. Analysis of variance showed that the growth performance in T1 was significantly higher than other groups (p 0.05). The formulate diet also had uniform growth rate with significant positive effects on Specific Growth Rate (SGR) and final biomass gain. The present study reveals that there is potential effect of commercial and formulated fish feed on growth performances of this target species.

On Investigation of Liquid Sloshing in Cylindrical Tanks With Single and Multiply Connected Domains Using Isogeometric Boundary Element Method

Abstract This paper explores an isogeometric boundary element method (IGA-BEM) for sloshing problems in cylindrical tanks with single and multiply connected domains. Instead of the Lagrange basis functions used in the standard BEM, the nonuniform rational B-splines (NURBS) basis functions are introduced to approximate the geometries of the problem boundaries and the unknown variables. Compared with the Lagrange basis functions, NURBS basis functions can accurately reconstruct the geometric boundary of analysis domain with almost no error, and all the data information for NURBS basis functions can be directly obtained from the computer-aided design (cad) or computer-aided engineering (cae) commercial software, which implies the modeling process of IGA-BEM is more simple than that of the standard BEM. NURBS makes it possible for the IGA-BEM to realize the seamless connection between cad and cae software with relative higher calculation accuracy than the standard BEM. Based on the weighted residual method as well as the divergence theorem, the IGA-BEM is developed for the single and multiply connected domains, whose boundaries are separately defined in the parameter space by different knot vectors. The natural sloshing frequencies of the liquid sloshing in a circular cylindrical tank with a coaxial or an off-center circular pipe, an elliptical cylindrical tank with an elliptical pipe, a circular cylindrical tank with multiple pipes are estimated with the introduced method by assuming an ideal (inviscid and incompressible) liquid, irrotational small-amplitude sloshing, and the linear free-surface condition. The comparison between the results obtained by the proposed method and those in the existing literatures shows very good agreements, which verifies the proposed model well. Meanwhile, the effects of radius ratio, liquid depth, number, and location of internal pipe (pipes) on the natural sloshing frequency and sloshing mode are analyzed carefully, and some conclusions are outlined finally.

NILE TILAPIA NURSERY IN A BIOFLOC SYSTEM: EVALUATION OF DIFFERENT STOCKING DENSITIES

This trial aimed to evaluate the growth performance and hematological parameters of Nile tilapia (Oreochromis niloticus) GIFT strain during nursery using different stock densities in a biofloc system. The experiment was conducted in circular tanks (400 L) with sexually reversed fish, weighing 6.74 ± 0.37 g, over a period of 35 days. Five treatments with three replicates each were used in a completely randomized design. The treatments were as follows: T1 (200 fishes m-3); T2 (300 fishes m-3); T3 (400 fishes m-3); T4 (500 fishes m-3), and T5 (600 fishes m-3). The fishes were fed four times a day, following a feed table for this species, with adjustments according to fish biomass. The water quality parameters total ammoniacal nitrogen, and unionized ammonia showed a significant difference (p<0.05) between the treatments with lower (T1) and higher stocking densities (T4, T5). Alkalinity was significantly higher in treatments with higher densities (T4 and T5). For hematological parameters, the number of thrombocytes was higher in T5. Hemoglobin concentration was significantly lower in T5 than in T3. The best productive indexes were found in T4, presenting final biomass of 9915.16 ± 14.80 g m-3, apparent feed conversion rate of 1.11 ± 0.02, mean survival of 95.75 ± 0.75%, and daily mean weight gain of 0.43 ± 0.07 g. Overall, the Nile tilapia nursery in a biofloc system showed higher individual growth at densities up to 300 fishes m-3 and increased stocking density up to 500 fishes m-3.

INFLUENCE OF Aspergillus oryzae FERMENTED SOYBEAN MEAL ON PLASMA CHOLESTEROL AND BILE ACID LEVELS IN HYBRID TILAPIA AND POMPANO FISH

Fermentation has been suggested as an economical and effective method to eliminate anti-nutritional factors and improve the nutritional value of Defatted soybean meal (SBM). The present study aimed to examine the effects of Aspergillus oryzae fermented SBM (FSBM) on plasma cholesterol and bile acid levels in hybrid tilapia and pompano. Two isonitrogenous and isoenergetic experimental diets for each fish species were formulated with SBM and FSBM as main ingredients. The diets were denoted as SBMD (SBM-based diet) and FSBMD (FSBM-based diet). Thirty juvenile hybrid tilapia (initial body weight 55 g) and eighteen juvenile pompanos (initial body weight 61 g) were allocated to each of the 4 concrete tanks (1500-L holding capacity) and each of the 4 circular polyvinyl chloride tanks (500-L holding capacity), respectively, resulting in two replicate tanks per dietary treatment for each fish species. For 4 weeks, the fish were handfed the experimental diets to apparent satiation twice daily. The results showed that feeding FSBMD tended to increase plasma total cholesterol level, gallbladdersomatic index, anterior intestinal total bile acid level, and posterior\anterior intestinal total bile acid reduction rate compared to SBMD in both hybrid tilapia and pompano. The differences in these parameters between FSBMD and SBMD dietary groups were significant in hybrid tilapia (P < 0.05), while no significant differences were found between pompano fed FSBMD and SBMD. These results indicated that fermentation of SBM with A. oryzae could effectively improve physiological conditions of hybrid tilapia fed soybean proteinbased diet and suggested that inclusion of A. oryzae FSBM might enhance growth and feed performances of the fish.

Seasonal Dynamics of the Ratio of Rheoreaction Types of Roach Rutilus rutilus

The seasonal dynamics of the motivational component of rheoreaction (ratio of rheoreaction types) has been studied in roach Rutilus rutilus L. inhabiting the Rybinsk Reservoir, Russia. The circular hydrodynamic tank with limnozone is used. The change in the ratio of rheoreaction types in nonmigratory mature roach may adequately reflect its behavior in the reservoir. The fish sex, stage of gonad maturation, and water temperature had a weak effect on the rheoreaction types and stability of their manifestation.

Vehicle’s components damage potentials of liquid cargo

The failure of vehicle’s suspension components has contributed to road crashes, while their defective operation can deteriorate the fuel efficiency of the vehicles. In this context, and when compared with solid cargo transporters, the road tankers would tend to produce larger roll forces during turning, as the curved shape of the liquid cargo container, shifts upwards the centre of gravity of the cargo. With reference to a rectangular cargo container representing the solid cargo situation, the increase in the position due to elliptical and circular tank shapes, can attain a value of 17% (100% fill, circular tank). In this study, experimental results comparing the lateral load transfer due to solid and liquid cargoes, indicate that the average force increase on the vehicle’s load-receiver side due to a liquid cargo, is 4.3%. To analyse the full-scale situation of both situations, that is, the higher position of the centre of gravity and the shifting of the liquid cargo, a simplified model is developed. The outputs from such a model when subjected to realistic operating conditions (speed and turning radius), suggest that the higher position of the centre of gravity due to using a non-rectangular cargo container generates an average force increase of 4.9% on the side receiving the load transfer. The incorporation of the effect of the liquid cargo, through the simple pendulum analogy, suggests that such an average increases to 6.76%, with a maximum of 8.35% in the case of the elliptical tank at 75% fill level. It is found that the average liquid cargo effect is 5.44%, which should be compared with the 4.3% of the experiments. Road tankers components would thus have a relatively shorter load cycle life than those of the solid cargo trucks.

Growth and hematological changes of Aspikutum, a hybrid of Leuciscus aspius female (Linnaeus, 1758) × Rutilus frisii male (Kamensky, 1901), fed rations with various protein to lipid ratio

A 60-day trial with six diets (three different protein levels × two different lipid levels) containing 30, 35 and 40% protein with 10 and 15% lipid levels was conducted to determine the optimum dietary protein to lipid ratio and effects on growth performance and hematological indices of Aspikutum, Leuciscus aspius female×Rutilus frisii male. Two hundred and fifty two fish (31.2±0.4 g; mean±SEM) were distributed in 18 circular concrete tanks (400 L) and were fed 3 times daily according to their apparent satiation. The results showed that the highest growth rate was achieved when fish fed with diet containing 35% protein and 15% lipid. Lipid productive value was significantly decreased with increasing dietary lipid level. Number of red blood cells, white blood cells, hemoglobin concentration, hematocrit value, mean corpuscular volume, mean corpuscular hemoglobin, neutrophil and eosinophil were not considerably differing among rearing treatments, while mean corpuscular hemoglobin concentration was significantly higher in fish fed with diet containing 30% protein and 10% lipid. The percentage of lymphocyte increased with increasing dietary lipid level, whereas a decrease of monocyte percentage was observed with increasing of dietary lipid level. Dietary protein and lipid level, as well as the interaction showed no significant differences in total lipid, triglyceride, cholesterol and total protein levels. In general, this study has indicated that diet containing 35% protein and 15% lipid had positive effects on growth performance, while no effects on biochemical and hematological parameters was achieved.

Computer aided calculus of the radial bridge kinetic energy of a sedimentation tank

The paper presents energy related aspects of a circular sedimentation tank’s radial bridge in order to assess the effectiveness of the equipment and to propose optimisations. In steady state conditions ETotal = EKinetic + ELosses where ETotal is provided by an electric motor of power P and the kinetic energy is , where . Several methods to assess the value of the J moment of inertia were explored. Finally, the moment of inertia is computed using an analytical method, by dividing the radial bridge in NC ‘simple shape’ components and by the use of an original C++ software consisting of >1700 computer code lines. Being a flexible and heavily parameterized original software, an optimised version of the radial bridge geometry was considered, for which Jopt = 83.57%. Jini We know the time in which a complete rotation is performed, T, therefore we compute ω and the kinetic energy. It results ELosses and we noticed that, because ω has a very small value, most of the ETotal energy is spent to cover the ‘losses’. The computation of the J moment of inertia allowed us to conclude regarding the effectiveness of the equipment and to extent the library of C++ header files to be reused in other software projects for the development of the hybrid models in mechanical engineering.

Partial seawater inclusion to improve Litopenaeus vannamei performance in low salinity biofloc systems

Litopenaeus vannamei production in oligohaline waters (0.5–5 g L−1) is a potential alternative for the continuous expansion of shrimp farming. However, ionic imbalance may affect physiological processes and productivity. In this work, natural seawater inoculation was used as strategy for correction of ionic composition in a biofloc-dominated oligohaline system and its effects on the water quality and nursery performance were evaluated. A 27-day trial was conducted using an experimental biofloc-dominated oligohaline water, salt formulation was based on the mean concentrations of the major ions present in natural oligohaline waters found in Northeastern Brazil. The trial was composed of four treatments of natural seawater inoculation (3, 6, 10 and 13%) and a control, without inoculation (0%); all with four replicates. Post-larvae (PL) of 22 days (0.057 ± 0.002 g) were stocked at 1000 PL m−3 in 20,150 L indoor circular tanks. Shrimp were fed 40% crude protein commercial diets twice a day at rations adjusted weekly. Water temperature, oxygen saturation, pH, total ammonia nitrogen, nitrite, nitrate, phosphate, alkalinity, hardness, salinity, conductivity, total suspended solids and settleable solids were monitored. Concentrations of the major ions were measured at the Days 0, 14 and 27. Shrimp sampling was performed weekly and the final zootechnical performance was evaluated by final weight, survival, specific growth rate (SGR), weekly growth rate (WGR), yield and food conversion ratio. Salinity, conductivity and hardness significantly increased according to the increase of seawater inoculation, whereas the other parameters did not differ; all of them were within the range recommended for shrimp culture at low salinity, except nitrate for 0%. Concentrations of Cl−, Na+, Mg2+ and K+ and Na+:K+ ratio significantly increased according to the increase of seawater inoculation. Final weight, survival, SGR, WGR and yield were significantly lower in the 0%, but no differences were found among the treatments (from 3% to 13%). The results found in this work indicate that a seawater inoculation at 3% was an efficient strategy to mitigate negative effects of the ionic imbalance on growth performance of PL reared in biofloc-dominated oligohaline systems.

Replacement of dietary fish oil with plant oils improves the immunological responses and the antioxidant status in Oreochromis niloticus exposed to suboptimal temperature.

Here, we investigated the effects of total dietary fish oil (FO) substitution with plant oil (PO) on hematological indices, immune status, antioxidant activity, IL1β and TNF-α gene expression, and hypoxia stress resistance in Oreochromis niloticus at suboptimal temperatures. Fish (n = 360) were randomly divided into 12 circular fiberglass tanks (500L; 3 replicates for each dietary group, 30 fish/replicate, 90 fish/group). The control group was fed a basal diet with FO as the lipid source. The CO, SFO, and LSO groups were fed a basal diet with complete replacement of FO with corn, sunflower, and linseed oils, respectively. After 4weeks, no effects on hematological indices were observed in fish fed the experimental diets. The LSO and CO groups showed a significant increase in γ globulin levels. The highest levels of non-specific immune parameters, antioxidant activity, and IL-1β and TNF-α gene expressions were recorded in the LSO group. The LSO group also exhibited good resistance to hypoxia stress. Therefore, the total dietary substitution of FO with PO (especially LSO and CO) is recommended as a valuable strategy to ameliorate the immunosuppressive effects of suboptimal temperatures and enhance the resistance of O. niloticus to hypoxia stress.

Liquid vibrations in circular cylindrical tanks with and without baffles under horizontal and vertical excitations

The paper is devoted to issues of numerical simulation of free surface elevations in rigid circular cylindrical fluid-filled tanks under external vertical and horizontal loadings with usage boundary element methods. The liquid in reservoirs is assumed to be ideal and incompressible, and its flow is irrotational. The influence of horizontal and vertical baffle installation is considered and damping effects due baffles are estimated. The influence of elasticity effects is considered. Free, forced and parametrical vibrations are examined. Modes of the free liquid vibrations present basic functions for analysis of forced and parametric vibrations. The modes and frequencies of the free liquid vibrations in baffled and un-baffled circular cylindrical tanks are received by using single- and multi-domain boundary element methods. The new effective procedure is developed for numerical solution of resolving system of singular integral equations. The problems of forced vibrations are reduced to solving the systems of second order ordinary differential equations. For parametric vibrations the system of Mathieu equations with non-zero right-hand parts is obtained. The numerical simulation of different kinds of loadings and baffle configurations is accomplished. The instability conditions of the fluid-filled tank subjected to both horizontal and vertical excitations are considered.

Liquid sloshing in an upright circular tank under periodic and transient excitations

Time-harmonic and periodically modulated swirling waves can be excited in an upright circular tank undergoing periodic oscillations in a single degree-of-freedom. The swirling direction is determined by the initial condition. While the time-harmonic swirling waves can reach steady state after the initial buildup, the periodically modulated swirling waves switch back and forth between planar waves and swirling waves.

Liquid Sloshing in a Cylindrical Tank with Multiple Baffles Under Horizontal and Pitching Motions

The sloshing response of fluid in a rigid circular cylindrical tank with multiple rigid annular baffles and subjected to horizontal and pitching excitations is investigated. The subdomain method for fluid sloshing is utilized to obtain exact solutions to the convective velocity potential of liquid. By substituting the velocity potential of liquid into free surface sloshing equation, the response equation under the horizontal excitation is constructed. According to producing the similar lateral force and moment as analytical solutions undergoing horizontal motion, an equivalent mass-spring model is developed to replace continuous liquid. Based on the model, dynamic response of liquid sloshing in the tank under the horizontal and pitching excitations is obtained. Compared with the reported results, the lateral force is in excellent agreement with literature solutions and the overturning moment shows good agreement with available solutions under the excitation with low frequency. The proposed model can be employed to simplify dynamics of complicated liquid-structure systems undergoing pitching motion without tedious derivation and great amount of calculation. The effects of the liquid height, the positions and sizes of the baffles on the influence coefficient factor of pitching motion and the steady-state response are revealed in detail.