Application of Computational Fluid Dynamics for Optimization of Grid Flocculation Tank

2016 ◽  
Vol 13 (10) ◽  
pp. 6457-6462
Author(s):  
Jianlin Liu ◽  
Qing Chang ◽  
Zhongshen Yi
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Middle Part ◽  
Front Part ◽  
Terminal Part ◽  
Turbulent Dissipation ◽  
Average Value ◽  
Treatment Processes ◽  
Successful Design ◽  
Computational Fluid Dynamics Cfd

Flocculation is a very important component of the overall suite of treatment processes. The need for a profound understanding and successful design/optimization of flocculation processes is important since the requirements for the removal of particulates have become increasingly stringent. The computational fluid dynamics (CFD) was used to design the flocculating tanks. The values of turbulent kinetic energy (k), turbulent dissipation rate (ε) and velocity gradient (G) were employed to evaluate the parameters of the flocculation tank using the realizable k − ε model. The best size of the grid in the front part of the tank was 80 mm × 80 mm. In this condition, the average value of k and ε were 0.00152 m2/s2 and 0.000570 m2/s3, respectively, and the percentage of G in the range of 70–100/s was 35.5%. For the middle part of the tank, the best size of the grid was 110 mm × 110 mm, with the average value of k and ε, as well as the percentage of G in the range of 40–60/s, were 0.00167 m2/s2, 0.000568 m2/s3 and 34.3%, respectively. In order to protect the flocs from being broken by stir, there was no grid in the terminal part of the tank. The optimized slice gap for both of the front part and the middle part of the tank were 600 mm.

scholarly journals Evaluating the Irrigation Effect of Continuous Flushing During Up-and-down Motion of Instruments Using a Computational Fluid Dynamics Model

2020 ◽  
Author(s):  
Linxi Guo ◽  
Xin Shi ◽  
Xiangfen Li ◽  
Yuanxi Zhao ◽  
qin su
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Static Solution ◽  
Apical Part ◽  
Middle Part ◽  
Original Solution ◽  
Mechanical Preparation ◽  
Irrigation Effect ◽  
Computational Fluid Dynamics Cfd

Abstract Background:The viscous environment caused by the rotation of Nickel-titanium (Ni-Ti) instruments in a static solution inside the root canal during mechanical preparation may increase the difficulty of endodontic debridement and the risk of instrument fatigue fracture. Therefore, this study aimed to investigate the effect of continuous flushing during up-and-down motion of instruments using a three-dimensional computational fluid dynamics (CFD) numerical model.Results:After30s simulation,water entering the canal formed an "efficient replacement area" in upper part of the canal and transported to the apical part of the canal.Increasing the velocity and amplitude of the motion of the instrument caused less time of flushing water to reach the apical area; and the replacement of the original solution was primarily improved by increasing the amplitude.Conclusions:Continuous flushing during up-and-down movement of the instrument significantly helped to rapidly replace the original solution with water at the coronal and middle part of the canal and dilutedthe viscosity of the original solution to some extend in the whole canal.It is therefore beneficial to add continuous water flushing to the instruments used in the preparation process.Furthermore, the amplitude of the movement in file’s up-and-down motion should be appropriately increased to improve its irrigation effect in clinical practice.

Efficiency prediction for storage chambers using computational fluid dynamics

1996 ◽  
Vol 33 (9) ◽  
pp. 163-170 ◽  
Author(s):  
Virginia R. Stovin ◽  
Adrian J. Saul
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Shear Stress ◽  
Particle Tracking ◽  
Critical Value ◽  
Complex Geometries ◽  
Bed Shear Stress ◽  
Breadth Ratio ◽  
Computational Fluid Dynamics Cfd ◽  
Simulated Flow

Research was undertaken in order to identify possible methodologies for the prediction of sedimentation in storage chambers based on computational fluid dynamics (CFD). The Fluent CFD software was used to establish a numerical model of the flow field, on which further analysis was undertaken. Sedimentation was estimated from the simulated flow fields by two different methods. The first approach used the simulation to predict the bed shear stress distribution, with deposition being assumed for areas where the bed shear stress fell below a critical value (τcd). The value of τcd had previously been determined in the laboratory. Efficiency was then calculated as a function of the proportion of the chamber bed for which deposition had been predicted. The second method used the particle tracking facility in Fluent and efficiency was calculated from the proportion of particles that remained within the chamber. The results from the two techniques for efficiency are compared to data collected in a laboratory chamber. Three further simulations were then undertaken in order to investigate the influence of length to breadth ratio on chamber performance. The methodology presented here could be applied to complex geometries and full scale installations.

Improvement of real-scale raceway bioreactors for microalgae production using Computational Fluid Dynamics (CFD)

2021 ◽  
Vol 54 ◽  
pp. 102207
Author(s):  
Cristian Inostroza ◽  
Alessandro Solimeno ◽  
Joan García ◽  
José M. Fernández-Sevilla ◽  
F. Gabriel Acién
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Computational Fluid Dynamics Cfd ◽  
Real Scale

scholarly journals Design of Novel Flash Ironmaking Reactors for Greatly Reduced Energy Consumption and CO2 Emissions

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 332
Author(s):  
Hong Yong Sohn ◽  
De-Qiu Fan ◽  
Amr Abdelghany
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Large Diameter ◽  
Reduction Reaction ◽  
The Novel ◽  
Height Ratio ◽  
Fine Iron ◽  
Computational Fluid Dynamics Cfd ◽  
High Reduction ◽  
Iron Ore Concentrate

The development of a novel ironmaking technology based on fine iron ore concentrate in a flash reactor is summarized. The design of potential industrial reactors for flash ironmaking based on the computational fluid dynamics technique is described. Overall, this simulation work has shown that the size of the reactor used in the novel flash ironmaking technology (FIT) can be quite reasonable vis-à-vis the blast furnaces. A flash reactor of 12 m diameter and 35 m height with a single burner operating at atmospheric pressure would produce 1.0 million tons of iron per year. The height can be further reduced by either using multiple burners, preheating the feed gas, or both. The computational fluid dynamics (CFD)-based design of potential industrial reactors for flash ironmaking pointed to a number of features that should be incorporated. The flow field should be designed in such a way that a larger portion of the reactor is used for the reduction reaction but at the same time excessive collision of particles with the wall must be avoided. Further, a large diameter-to-height ratio that still allows a high reduction degree should be used from the viewpoint of decreased heat loss. This may require the incorporation of multiple burners and solid feeding ports.

scholarly journals Morphological and Hemodynamic Changes during Cerebral Aneurysm Growth

2021 ◽  
Vol 11 (4) ◽  
pp. 520
Author(s):  
Emily R. Nordahl ◽  
Susheil Uthamaraj ◽  
Kendall D. Dennis ◽  
Alena Sejkorová ◽  
Aleš Hejčl ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Swirling Flow ◽  
Morphological Changes ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Aneurysm Wall ◽  
Aneurysm Growth ◽  
Computational Fluid Dynamics Cfd

Computational fluid dynamics (CFD) has grown as a tool to help understand the hemodynamic properties related to the rupture of cerebral aneurysms. Few of these studies deal specifically with aneurysm growth and most only use a single time instance within the aneurysm growth history. The present retrospective study investigated four patient-specific aneurysms, once at initial diagnosis and then at follow-up, to analyze hemodynamic and morphological changes. Aneurysm geometries were segmented via the medical image processing software Mimics. The geometries were meshed and a computational fluid dynamics (CFD) analysis was performed using ANSYS. Results showed that major geometry bulk growth occurred in areas of low wall shear stress (WSS). Wall shape remodeling near neck impingement regions occurred in areas with large gradients of WSS and oscillatory shear index. This study found that growth occurred in areas where low WSS was accompanied by high velocity gradients between the aneurysm wall and large swirling flow structures. A new finding was that all cases showed an increase in kinetic energy from the first time point to the second, and this change in kinetic energy seems correlated to the change in aneurysm volume.

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