scholarly journals Experimental & Computational Fluid Dynamics Study of the Suitability of Different Solid Feed Pellets for Aquaculture Systems

2020 ◽  
Vol 10 (19) ◽  
pp. 6954
Author(s):  
Štěpán Papáček ◽  
Karel Petera ◽  
Petr Císař ◽  
Vlastimil Stejskal ◽  
Mohammadmehdi Saberioon
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Residence Time ◽  
Raw Materials ◽  
Fish Feed ◽  
Maximum Difference ◽  
Geometrical Properties ◽  
Composition Formula ◽  
Feed Pellets ◽  
Fish Tank

Fish feed delivery is one of the challenges which fish farmers encounter daily. The main aim of the feeding process is to ensure that every fish is provided with sufficient feed to maintain desired growth rates. The properties of fish feed pellet, such as water stability, degree of swelling or floating time, are critical traits impacting feed delivery. Some considerable effort is currently being made with regard to the replacement of fish meal and fish oil with other sustainable alternative raw materials (i.e., plant or insect-based) with different properties. The main aim of this study is to investigate the motion and residence time distribution (RTD) of two types of solid feed pellets with different properties in a cylindrical fish tank. After experimental identification of material and geometrical properties of both types of pellets, a detailed 3D computational fluid dynamics (CFD) study for each type of pellets is performed. The mean residence time of pellets injected at the surface of the fish tank can differ by up to 75% depending on the position of the injection. The smallest residence time is when the position is located at the center of the liquid surface (17 s); the largest is near the edge of the tank (75 s). The maximum difference between the two studied types of pellets is 25% and it increases with positions closer to the center of the tank. The maximum difference for positions along the perimeter at 3/4 tank radius is 8%; the largest residence times are observed at the opposite side of the water inlet. Based on this study, we argue that the suitability of different solid feed pellets for aquaculture systems with specific fish can be determined, and eventually the pellet composition (formula) as well as the injection position can be optimized.

scholarly journals Computational fluid dynamics analysis of the hydraulic (filtration) efficiency of a residential swimming pool

2018 ◽  
Vol 16 (5) ◽  
pp. 750-761 ◽  
Author(s):  
J. Zhang ◽  
N. Sinha ◽  
M. Ross ◽  
A. E. Tejada-Martínez
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Residence Time ◽  
Dead Zone ◽  
Three Dimensional ◽  
Circulation Pattern ◽  
Filtration Efficiency ◽  
Swimming Pools ◽  
Hydraulic Efficiency ◽  
Computational Fluid Dynamics Analysis

Abstract Hydraulic or filtration efficiency of residential swimming pools, quantified in terms of residence time characteristics, is critical to disinfection and thus important to public health. In this study, a three-dimensional computational fluid dynamics model together with Eulerian and Lagrangian-based techniques are used for investigating the residence time characteristics of a passive tracer and particles in the water, representative of chemicals and pathogens, respectively. The flow pattern in the pool is found to be characterized by dead zone regions where water constituents may be retained for extended periods of times, thereby potentially decreasing the pool hydraulic efficiency. Two return-jet configurations are studied in order to understand the effect of return-jet location and intensity on the hydraulic efficiency of the pool. A two-jet configuration is found to perform on par with a three-jet configuration in removing dissolved constituents but the former is more efficient than the latter in removing or flushing particles. The latter result suggests that return-jet location and associated flow circulation pattern have an important impact on hydraulic efficiency. Thus return-jet configuration should be incorporated as a key parameter in the design of swimming pools complementing current design standards.

scholarly journals Validation of a Computational Fluid Dynamics Model for a Novel Residence Time Distribution Analysis in Mixing at Cross-Junctions

Water ◽  
2018 ◽  
Vol 10 (6) ◽  
pp. 733 ◽  
Author(s):  
Daniel Hernández-Cervantes ◽  
Xitlali Delgado-Galván ◽  
José Nava ◽  
P. López-Jiménez ◽  
Mario Rosales ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Distribution Analysis ◽  
Dynamics Model ◽  
Computational Fluid Dynamics Model

Evaluation of Flow Characteristics in an Oil-Water Separator Using Computational Fluid Dynamics

2020 ◽  
Author(s):  
Terry Potter ◽  
Tathagata Acharya
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Residence Time ◽  
Water Volume ◽  
Multiphase Model ◽  
Two Phase ◽  
Water Separator ◽  
Oil Water ◽  
Simulation Results ◽  
Water Cut

Abstract Multiphase separators on production platforms are among the first equipment through which well fluids flow. Based on functionality, multiphase separators can either be two-phase that separate oil from water, or three-phase that separate oil, natural gas, and water. Separator performances are often evaluated using mean residence time (MRT) of the hydrocarbon phase. MRT is defined as the amount of time a given phase stays inside the separator. On field, operators usually measure MRT as the ratio of active volume occupied by each phase to the phase volumetric flowrate. However, this method may involve significant errors as the oil-water interface height is obtained using level controllers and the volume occupied by each phase is calculated assuming the interface can be extrapolated from the weir back to the separator inlet. In this study, authors perform computational fluid dynamics (CFD) on a two-phase horizontal separator to evaluate MRT as a function of varying water volume flowrates (water-cut) in a mixture of water and oil. The authors use residence time distributions (RTD) to obtain MRT at each water-cut — a method that results in significantly more accurate results than the regular method used by operators. The numerical model is developed with commercial software package ANSYS Fluent. The code uses the Eulerian multiphase model along with the k-ε turbulence model. The simulation results show agreement with experiments performed by previous researchers. Additional simulations are performed to assess the effect of various separator internals on separator performance. Simulation results suggest that the model developed in this study can be used to predict performances of two-phase liquid-liquid separators with reasonable accuracy and will be useful towards their design to improve performances under various inlet flow conditions.

Hemodynamics of neonatal double lumen cannula malposition

Perfusion ◽  
2019 ◽  
Vol 35 (4) ◽  
pp. 306-315
Author(s):  
Muhammad Jamil ◽  
Mohammad Rezaeimoghaddam ◽  
Bilgesu Cakmak ◽  
Yahya Yildiz ◽  
Reza Rasooli ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Inferior Vena Cava ◽  
Residence Time ◽  
Inferior Vena ◽  
Superior Vena ◽  
Vena Cava ◽  
Right Atrial ◽  
Patient Specific ◽  
Blood Damage

Objective: Malposition of dual lumen cannula is a frequent and challenging complication in neonates and plays a significant role in shaping the in vitro device hemodynamics. This study aims to analyze the effect of the dual lumen cannula malposition on right-atrial hemodynamics in neonatal patients using an experimentally validated computational fluid dynamics model. Methods: A computer model was developed for clinically approved dual lumen cannula (13Fr Origen Biomedical, Austin, Texas, USA) oriented inside the atrium of a 3-kg neonate with normal venous return. Atrial hemodynamics and dual lumen cannula malposition were systematically simulated for two rotations (antero-atrial and atrio-septal) and four translations (two intravascular movements along inferior vena cava and two dislodged configurations in the atrium). A multi-domain compartmentalized mesh was prepared to allow the site-specific evaluation of important hemodynamic parameters. Transport of each blood stream, blood damage levels, and recirculation times are quantified and compared to dual lumen cannula in proper position. Results: High recirculation levels (39 ± 4%) in malpositioned cases resulted in poor oxygen saturation where maximum recirculation of up to 42% was observed. Apparently, Origen dual lumen cannula showed poor inferior vena cava blood–capturing efficiency (48 ± 8%) but high superior vena cava blood–capturing efficiency (86 ± 10%). Dual lumen cannula malposition resulted in corresponding changes in residence time (1.7 ± 0.5 seconds through the tricuspid). No significant differences in blood damage were observed among the simulated cases compared to normal orientation. Compared to the correct dual lumen cannula position, both rotational and translational displacements of the dual lumen cannula resulted in significant hemodynamic differences. Conclusion: Rotational or translational movement of dual lumen cannula is the determining factor for atrial hemodynamics, venous capturing efficiency, blood residence time, and oxygenated blood delivery. Results obtained through computational fluid dynamics methodology can provide valuable foresight in assessing the performance of the dual lumen cannula in patient-specific configurations.

scholarly journals Optimization of a Continuous Hybrid Impeller Mixer via Computational Fluid Dynamics

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
N. Othman ◽  
S. K. Kamarudin ◽  
M. S. Takriff ◽  
M. I. Rosli ◽  
E. M. F. Engku Chik ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Operating Conditions ◽  
Impeller Speed ◽  
Transient Condition ◽  
Experimental Investigations ◽  
Rushton Turbine

This paper presents the preliminary steps required for conducting experiments to obtain the optimal operating conditions of a hybrid impeller mixer and to determine the residence time distribution (RTD) using computational fluid dynamics (CFD). In this paper, impeller speed and clearance parameters are examined. The hybrid impeller mixer consists of a single Rushton turbine mounted above a single pitched blade turbine (PBT). Four impeller speeds, 50, 100, 150, and 200 rpm, and four impeller clearances, 25, 50, 75, and 100 mm, were the operation variables used in this study. CFD was utilized to initially screen the parameter ranges to reduce the number of actual experiments needed. Afterward, the residence time distribution (RTD) was determined using the respective parameters. Finally, the Fluent-predicted RTD and the experimentally measured RTD were compared. The CFD investigations revealed that an impeller speed of 50 rpm and an impeller clearance of 25 mm were not viable for experimental investigations and were thus eliminated from further analyses. The determination of RTD using ak-εturbulence model was performed using CFD techniques. The multiple reference frame (MRF) was implemented and a steady state was initially achieved followed by a transient condition for RTD determination.

Based on Particle Size of Cuttings to Study the Erosion of the Plugged Tee in Air Drilling

2014 ◽  
Vol 607 ◽  
pp. 193-196
Author(s):  
Li Hong Zhu ◽  
Rui He Wang ◽  
Yong Huang ◽  
Jing Yin Wang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Particle Size ◽  
Mathematical Models ◽  
Residence Time ◽  
Compressed Air ◽  
Exhaust Pipe ◽  
Air Drilling ◽  
Computational Fluid Dynamics Cfd ◽  
Motion Paths

Plugged tee is the easilyworn part of an exhaust pipe during air drilling because of the flow of the compressed air with the entrained cutting particles. The effects of the particle size on the erosion of the plugged tee are studied by computational fluid dynamics (CFD). Mathematical models of the flow of the compressed air with the entrained cutting particles through the plugged tee are built and imported into the CFD through embedding procedures. After boundary conditions and the parameter of the particle size are given, the motion paths of cuttings in the different particle size in the plugged tee and its effects on erosion of the plugged tee are obtained. Erosions in the plugged tee are mainly distributed in the wall of the buffer segment and the joints and mainly caused by the scope of the particle size of cuttings. The motion paths and the residence time of cuttings with different particle size are different, so the erosions of the joints and the buffer segment are different.

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