scholarly journals Three-dimensional numerical simulation of flow in vertical slot fishways: validation of the model and characterization of the flow

RBRH ◽  
2019 ◽  
Vol 24 ◽  
Author(s):  
Daniela Guzzon Sanagiotto ◽  
Júlia Brusso Rossi ◽  
Luísa Lüdtke Lauffer ◽  
Juan Martín Bravo
Keyword(s):  
Numerical Simulation ◽  
Computational Cost ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Maximum Flow ◽  
Mean Value ◽  
Vertical Slot ◽  
Longitudinal Slope ◽  
The Mean

ABSTRACT Vertical slot fishways allow energy dissipation as a function of the pool, longitudinal slope, baffle and vertical slot design. The mean and turbulent flow patterns in these structures must be compatible with the fish target. The design of these structures is commonly based on previous successful fishways as well as simplified theoretical equations and empirical relationships. To aid in the design of these structures, a three-dimensional hydrodynamic model was used to simulate the flow, and experimental studies were used to validate the model. The mean velocities, pressures and parameters indicative of turbulence were analyzed. The maximum flow velocities were up to 32% higher than the values obtained using a simplified theoretical equation. The evaluation of the volumetric dissipated power indicated that the mean value for the pool was lower than 150 W/m3; however, analysis of the spatial distribution showed that in some areas, the values can exceed 1000 W/m3. The results indicate that the numerical simulation was able to adequately represent the flow considering the computational cost involved. Accordingly, it can be used as a complementary tool for the design of new fishways and for the analysis of modifications in existing ones.

Dynamic Characterization of a Valveless Micropump Considering Entrapped Gas Bubbles

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Songjing Li ◽  
Jixiao Liu ◽  
Dan Jiang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Experimental Studies ◽  
Gas Bubbles ◽  
Chamber Pressure ◽  
Dynamic Characterization ◽  
Valveless Micropump ◽  
Performance Deterioration ◽  
Trapped Gas

Unexpected gas bubbles in microfluidic devices always bring the problems of clogging, performance deterioration, and even device functional failure. For this reason, the aim of this paper is to study the characterization variation of a valveless micropump under different existence conditions of gas bubbles based on a theoretical modeling, numerical simulation, and experiment. In the theoretical model, we couple the vibration of piezoelectric diaphragm, the pressure drop of the nozzle/diffuser and the compressibility of working liquid when gas bubbles are entrapped. To validate the theoretical model, numerical simulation and experimental studies are carried out to investigate the variation of the pump chamber pressure influenced by the gas bubbles. Based on the numerical simulation and the experimental data, the outlet flow rates of the micropump with different size of trapped gas bubbles are calculated and compared, which suggests the influence of the gas bubbles on the dynamic characterization of the valveless micropump.

3D Numerical Simulation of Polydisperse Pressurized Gas-Solid Fluidized Bed

2011 ◽  
Author(s):  
P. Fede ◽  
O. Simonin ◽  
I. Ghouila
Keyword(s):  
Numerical Simulation ◽  
Fluidized Bed ◽  
Ethylene Polymerization ◽  
Solid Phase ◽  
Three Dimensional ◽  
Gas Velocity ◽  
Particle Segregation ◽  
3D Numerical Simulation ◽  
Model Predictions ◽  
The Mean

Three dimensional unsteady numerical simulations of dense pressurized polydisperse fluidized bed have been carried out. The geometry is a medium-scale industrial pilot for ethylene polymerization. The numerical simulation have been performed with a polydisperse collision model. The consistency of the polydisperse model predictions with the monodisperse ones is shown. The results show that the pressure distribution and the mean vertical gas velocity are not modified by polydispersion of the solid phase. In contrast, the solid particle species are not identically distributed in the fluidized bed indicating the presence of particle segregation.

scholarly journals Nanometer Scale Tomographic Investigation of Fine Scale Precipitates in a CuFeNi Granular System by Three-Dimensional Field Ion Microscopy

2012 ◽  
Vol 18 (5) ◽  
pp. 1129-1134 ◽  
Author(s):  
Sophie Cazottes ◽  
François Vurpillot ◽  
Abdeslem Fnidiki ◽  
Dany Lemarchand ◽  
Marcello Baricco ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Precise Determination ◽  
Atomic Scale ◽  
Granular System ◽  
Field Ion Microscopy ◽  
Mean Diameter ◽  
The Matrix ◽  
The Mean ◽  
Ion Microscopy

AbstractThe microstructure of Cu80Fe10Ni10 (at. %) granular ribbons was investigated by means of three-dimensional field ion microscopy (3D FIM). This ribbon is composed of magnetic precipitates embedded in a nonmagnetic matrix. The magnetic precipitates have a diameter smaller than 5 nm in the as-spun state and are coherent with the matrix. No accurate characterization of such a microstructure has been performed so far. A tomographic characterization of the microstructure of melt spun and annealed Cu80Fe10Ni10 ribbon was achieved with 3D FIM at the atomic scale. A precise determination of the size distribution, number density, and distance between the precipitates was carried out. The mean diameter for the precipitates is 4 nm in the as-spun state. After 2 h at 350°C, there is an increase of the size of the precipitates, while after 2 h at 400°C the mean diameter of the precipitates decreases. Those data were used as inputs in models that describe the magnetic and magnetoresistive properties of this alloy.

scholarly journals HEMATOLOGICAL CHARACTERIZATION OF BETA-THALASSEMIA IN SUDANESE PATIENTS

2020 ◽  
pp. 5-7
Author(s):  
RABAB HASSAN ELSHAIKH ◽  
SANAA ELFATIH HUSSEIN
Keyword(s):  
Iron Deficiency ◽  
Hemoglobin Concentration ◽  
Mean Value ◽  
Beta Thalassemia ◽  
Mean Corpuscular Hemoglobin ◽  
Corpuscular Hemoglobin ◽  
Significant Difference ◽  
Hematological Analysis ◽  
The Mean

Thalassemia is common inherited disorder among humans, and they represent a major public health problem in many areas of the world. The study aimed to the measurement of hematological characterization of beta-thalassemia in Sudanese patients. Blood samples from 61 beta-thalassemic patients were collected after written consent form obtained from all participants. The frequency of adults (>18 years) was 45 (73.8%) and children’s (<18 years) was 16 (26.2%); the frequency of male was 27 (44.3%) and 34 were female (55.7%). Hemoglobin estimation and red cell indices were carried out using the automatic blood cell counter Sysmex K × 21N. The results showed that Hb and RBCs indices were varied between mild to moderate and severe decreasing, hemoglobin concentration (Hb) with the mean value of 9.6 g/dL, with minimum value of 6.1 g/dl and maximum of 11.9 g/dl, while RBCs were increased in all patients, mean value 5.2 c/l, mean corpuscular volume mean was 58.9 fl, hematocrit was 30.4, mean corpuscular hemoglobin (MCH) 18.8 pg, mean corpuscular hemoglobin concentration (MCHC) was 31.7pg, and RDW was 18.8%. The method used for hemoglobin electrophoresis was capillary electrophoresis, Hb pattern shows increased HbA2 and HbF, the mean of HbA is 78.3%, HbF is 2.3%, and HbA2 is 6.5% with the min. value of 3.6% and max. of 12.2%. While the mean of serum iron was 82.75 μg/dl, 7 patients showed low level, 19 high level, and 35 were normal level. Comparison of hematological analysis (HbA2) in thalassemic patients coexisted with iron deficiency and without result was insignificant difference (p=0.645), this result disagrees with references that say iron deficiency masking HbA2. Nevertheless, the association between HbA2 and HbF revealed a statistically significant difference (p<0.013) and HbA2 with Hb was insignificant (p=0.260).

Synthesis and Characterization of the Manganese Pyroarsenate Mn2As2O7 · 2H2O

2001 ◽  
Vol 56 (4-5) ◽  
pp. 359-363 ◽  
Author(s):  
N. Stock ◽  
G. D. Stucky ◽  
A. K. Cheetham
Keyword(s):  
Three Dimensional ◽  
Spectroscopic Studies ◽  
Mean Value ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Raman Spectroscopic ◽  
Distorted Octahedral ◽  
Ir And Raman ◽  
Hydrothermal Methods

Abstract The manganese pyroarsenate hydrate, Mn2As2O7 · 2 H2O, has been obtained as a single phase product using hydrothermal methods and the structure has been determined by single crystal X-ray diffraction. The title compound crystallizes in the monoclinic space group P21/n with a = 6.6576(4), b = 14.555(1), c = 7.8147(5) Å, β = 94.935(1)°, V = 754.46(8) Å3 and Z = 4. The manganese ions are each coordinated to five oxygen atoms and a water molecule in a distorted octahedral arrangement. Edge-sharing MnO6 octahedra form chains which are connected to a three-dimensional framework by As2O74- ions. The pyroarsenate anion, which attains a nearly eclipsed conformation, has a mean As-O distance for the terminal As-O bonds of 1.669(2) Å, while for the bridging oxygen atom a mean value of 1.757(2) Å is observed. Magnetic susceptibility measurements indicate the presence of high-spin Mn2+ ions. Thermogravimetric as well as IR and Raman spectroscopic studies of Mn2As2O7 · 2 H2O are presented.

Numerical and Experimental Investigation of Secondary Flow in a High Speed Compressor Stator

1995 ◽  
Author(s):  
Y. Ohkita ◽  
H. Kodama ◽  
O. Nozaki ◽  
K. Kikuchi ◽  
A. Tamura
Keyword(s):  
Numerical Simulation ◽  
Experimental Investigation ◽  
Shear Flow ◽  
Secondary Flow ◽  
Total Pressure ◽  
High Speed ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Three Dimensional Flow ◽  
Performance Recovery

A series of numerical and experimental studies have been conducted to understand the mechanism of loss generation in a high speed compressor stator with inlet radial shear flow over the span. In this study, numerical simulation is extensively used to investigate the complex three-dimensional flow in the cascades and to interpret the phenomena appeared in the high speed compressor tests. It has been shown that the inlet radial shear flow generated by upstream rotor had a significant influence on the stator secondary flow, and consequently on the total pressure loss. Redesign of the stator aiming at the reduction of loss by controlling secondary flow has been carried out and the resultant performance recovery was successfully demonstrated both numerically and experimentally.

scholarly journals Detection of the Strains Induced in Murine Tibias by Ex Vivo Uniaxial Loading with Different Sensors

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5109
Author(s):  
Emanuele Rizzuto ◽  
Barbara Peruzzi ◽  
Mariagrazia Giudice ◽  
Enrica Urciuoli ◽  
Erika Pittella ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Ex Vivo ◽  
Mean Value ◽  
Uniaxial Loading ◽  
Image Correlation ◽  
Strain Gauges ◽  
Experimental Conditions ◽  
The Mean

In this paper, the characterization of the main techniques and transducers employed to measure local and global strains induced by uniaxial loading of murine tibiae is presented. Micro strain gauges and digital image correlation (DIC) were tested to measure local strains, while a moving coil motor-based length transducer was employed to measure relative global shortening. Local strain is the crucial parameter to be measured when dealing with bone cell mechanotransduction, so we characterized these techniques in the experimental conditions known to activate cell mechanosensing in vivo. The experimental tests were performed using tibia samples excised from twenty-two C57BL/6 mice. To evaluate measurement repeatability we computed the standard deviation of ten repetitive compressions to the mean value. This value was lower than 3% for micro strain gauges, and in the range of 7%–10% for DIC and the length transducer. The coefficient of variation, i.e., the standard deviation to the mean value, was about 35% for strain gauges and the length transducer, and about 40% for DIC. These results provided a comprehensive characterization of three methodologies for local and global bone strain measurement, suggesting a possible field of application on the basis of their advantages and limitations.

scholarly journals Direct Numerical Simulation of Flow around a Circular Cylinder Controlled Using Plasma Actuators

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Taichi Igarashi ◽  
Hiroshi Naito ◽  
Koji Fukagata
Keyword(s):  
Numerical Simulation ◽  
Circular Cylinder ◽  
Direct Numerical Simulation ◽  
Drag Reduction ◽  
Three Dimensional ◽  
Reduction Rate ◽  
Plasma Actuators ◽  
Two Dimensional ◽  
Freestream Velocity ◽  
The Mean

Flow around a circular cylinder controlled using plasma actuators is investigated by means of direct numerical simulation (DNS). The Reynolds number based on the freestream velocity and the cylinder diameter is set atReD=1000. The plasma actuators are placed at±90° from the front stagnation point. Two types of forcing, that is, two-dimensional forcing and three-dimensional forcing, are examined and the effects of the forcing amplitude and the arrangement of plasma actuators are studied. The simulation results suggest that the two-dimensional forcing is primarily effective in drag reduction. When the forcing amplitude is higher, the mean drag and the lift fluctuations are suppressed more significantly. In contrast, the three-dimensional forcing is found to be quite effective in reduction of the lift fluctuations too. This is mainly due to a desynchronization of vortex shedding. Although the drag reduction rate of the three-dimensional forcing is slightly lower than that of the two-dimensional forcing, considering the power required for the forcing, the three-dimensional forcing is about twice more efficient.

scholarly journals On the zeroth law of turbulence for the stochastically forced Navier-Stokes equations

2021 ◽  
Vol 0 (0) ◽  
pp. 0
Author(s):  
Yat Tin Chow ◽  
Ali Pakzad
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Energy Dissipation Rate ◽  
Mean Value ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Additional Hypothesis ◽  
The Mean ◽  
Deterministic Force ◽  
Martingale Solutions

<p style='text-indent:20px;'>We consider the three-dimensional stochastically forced Navier–Stokes equations subjected to white-in-time (colored-in-space) forcing in the absence of boundaries. Upper bounds of the mean value of the time-averaged energy dissipation rate are derived directly from the equations for weak (martingale) solutions. This estimate is consistent with the Kolmogorov dissipation law. Moreover, an additional hypothesis of energy balance implies the zeroth law of turbulence in the absence of a deterministic force.</p>

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