scholarly journals Structural improvements on hydrodynamic separators: a computational fluid dynamics approach

2016 ◽  
Vol 74 (12) ◽  
pp. 2898-2908
Author(s):  
Joseph Albert Mendoza ◽  
Dong Hoon Lee ◽  
Sang-Il Lee ◽  
Joo-Hyon Kang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fine Particles ◽  
Swirling Flow ◽  
Particle Removal ◽  
Gravity Settling ◽  
Large Particles ◽  
Removal Efficiencies ◽  
Structural Configurations ◽  
Plate Type

Hydrodynamic separators (HDSs) have been used extensively to reduce stormwater pollutants from urbanized areas before entering the receiving water bodies. They primarily remove particulates and associated pollutants using gravity settling. Two types of HDSs with different structural configurations of the inner vortex-inducing components were presented in this study. One configuration consisted of a dip cylindrical plate with a center shaft while the other one has a hollow screen inside. With the help of computational fluid dynamics, the performance of these different types of HDSs have been evaluated and comparatively analyzed. The results showed that the particle removal efficiency was better with the cylindrical plate type HDSs than the screen type HDSs because of the larger swirling flow regime formed inside the device. Plate type HDSs were found more effective in removing fine particles (∼50 μm) than the screen type HDSs that were only efficient in removing large particles (≥250 μm). Structural improvements in a HDS such as increase in diameter and angle of the inlet pipe can enhance the removal efficiencies by up to 20% for plate type HDS while increase in the screen diameter can increase removal efficiencies of the screen type HDS.

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.

Application of an Angular Momentum Balance Method for Investigating Numerical Accuracy in Swirling Flow

2003 ◽  
Vol 125 (4) ◽  
pp. 723-730
Author(s):  
H. Nilsson ◽  
L. Davidson
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Angular Momentum ◽  
Swirling Flow ◽  
Linear Momentum ◽  
Correct Solution ◽  
Momentum Balance ◽  
Numerical Accuracy ◽  
Water Turbine ◽  
Water Turbines

This work derives and applies a method for the investigation of numerical accuracy in computational fluid dynamics. The method is used to investigate discretization errors in computations of swirling flow in water turbines. The work focuses on the conservation of a subset of the angular momentum equations that is particularly important to swirling flow in water turbines. The method is based on the fact that the discretized angular momentum equations are not necessarily conserved when the discretized linear momentum equations are solved. However, the method can be used to investigate the effect of discretization on any equation that should be conserved in the correct solution, and the application is not limited to water turbines. Computations made for two Kaplan water turbine runners and a simplified geometry of one of the Kaplan runner ducts are investigated to highlight the general and simple applicability of the method.

scholarly journals Investigation of dust particle removal efficiency of self-priming venturi scrubber using computational fluid dynamics

2018 ◽  
Vol 50 (5) ◽  
pp. 665-672 ◽  
Author(s):  
Sarim Ahmed ◽  
Hassan Mohsin ◽  
Kamran Qureshi ◽  
Ajmal Shah ◽  
Waseem Siddique ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Dust Particle ◽  
Removal Efficiency ◽  
Particle Removal ◽  
Venturi Scrubber

scholarly journals Modeling of hydrodynamics of fine particles deposition in packed-bed reactors

2017 ◽  
Vol 9 (4) ◽  
pp. 157-168 ◽  
Author(s):  
Shahid Rabbani ◽  
Mohamed Sassi ◽  
Tariq Shamim
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Particle Deposition ◽  
Fine Particles ◽  
Collection Efficiency ◽  
Packed Bed ◽  
Dynamics Model ◽  
Momentum Exchange ◽  
Packed Bed Reactors ◽  
Computational Fluid Dynamics Model

With the passage of time for chemical operations involving packed-bed reactors, especially in petroleum refining and petrochemical industries, non-filterable fines such as coke, corrosion products and fine clay in oilsands bitumen deposit on the catalyst particles. The gradual entrapment and deposition of fine particles of range 0.7–20 µm cause the pore-plugging phenomenon to occur which consequently blocks the flow passages inside the porous medium. To understand the plugging phenomenon and its effect on hydrodynamic of the reactor, we developed a computational fluid dynamics model which is based on reactor collection efficiency, filtration rate, Brownian motion and interfacial momentum exchange terms to simulate the pressure drop due to deposition of fine particles in real conditions. With the help of this model, we have studied the effect of fines deposition on bed porosity and clogging. This is for the first time that Ansys Fluent has been used to simulate fine-particle deposition in packed-bed conditions. The result was a Eulerian–Eulerian 2-D computational fluid dynamics model which considered all the three phases, i.e. liquid, catalyst and fine particles. The results were validated against the experiments reported in the literature and reached good agreement.

Experimental and numerical study of vortex gripper with a diversion body

2011 ◽  
Vol 226 (6) ◽  
pp. 1526-1534 ◽  
Author(s):  
Q Wu ◽  
Q Ye ◽  
G X Meng
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Computational Fluid Dynamics ◽  
Swirling Flow ◽  
Numerical Study ◽  
Reynolds Stress Model ◽  
Stress Model ◽  
Lifting Force ◽  
Handling Device ◽  
Simulation Results

This article introduces a new vortex gripper with a diversion body. Vortex gripper, as a pneumatic non-contact handling device, can generate lifting force to hold a workpiece without any contact. In order to predict the characteristics of this new vortex gripper, including pressure distribution on the upper surface of the workpiece, lifting force, supporting stiffness, and flowrate, a computational fluid dynamics study has been carried out. In the vortex cup, air swirling flow is a complex turbulent one; so Reynolds stress model (RSM) was used to describe internal air swirling flow. In addition, an experiment was carried out to study the characteristics of the vortex gripper. When compared with the experimental results, the reliability of numerical simulation results by RSM was verified. The vortex gripper with a diversion body could generate greater lifting force when compared with those designed by Xin et al. with the same air consumption. Therefore, the efficiency of the vortex gripper is improved.

scholarly journals A Numerical Study of the Impact of Radial Baffles in Solid Bowl Centrifuges Using Computational Fluid Dynamics

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
Xiana Romaní Fernández ◽  
Hermann Nirschl
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Multiphase Flow ◽  
Fine Particles ◽  
Numerical Study ◽  
Small Particles ◽  
Sedimentation Behavior ◽  
Computational Fluid Dynamics Cfd ◽  
Separation Equipment ◽  
The Impact

Centrifugal separation equipment, such as solid bowl centrifuges, is used to carry out an effective separation of fine particles from industrial fluids. Knowledge of the streams and sedimentation behavior inside solid bowl centrifuges is necessary to determine the geometry and the process parameters that lead to an optimal performance. Regarding a given industrial centrifuge geometry, a grid was built to calculate numerically the multiphase flow of water, air, and particles with a computational fluid dynamics (CFD) software. The effect of internal radial baffles on the multiphase flow was investigated. The results show that the baffles are helpful for the acceleration of the fluid, but they disturb the axial boundary layer, making it irregular, and originate a secondary circulating flow which hinders the sedimentation of small particles.

scholarly journals Minimising exposure to droplet and aerosolised pathogens: a computational fluid dynamics study

2020 ◽  
Author(s):  
Paolo Perella ◽  
Mohammad Tabarra ◽  
Ertan Hataysal ◽  
Amir Pournasr ◽  
Ian Renfrew
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Suction Catheter ◽  
Particle Removal ◽  
Ansys Fluent ◽  
Protective Shield ◽  
Pragmatic Clinical Trials ◽  
Fluent Software ◽  
Dynamics Modelling ◽  
Suction Flow

BackgroundHazardous pathogens are spread in either droplets or aerosols produced during aerosol generating procedures (AGP). Adjuncts minimising exposure of healthcare workers to hazardous pathogens released during AGP may be beneficial. We used state-of-the-art Computational Fluid Dynamics modelling to optimise the performance of a custom-designed shield.MethodsWe modelled airflow patterns and trajectories of particles (size range 1–500µm) emitted during a typical cough using Computational Fluid Dynamics (ANSYS Fluent software), in the presence and absence of a protective shield enclosing the head of a patient. We modelled the effect of different shield designs, suction tube position, and suction flow rate on particle escape from the shield.ResultsUse of the shield prevented escape of 99.1–100% of particles, which were either trapped on the shield walls (16–21%) or extracted via suction (79–82%). At most, 0.9% particles remained floating inside the shield. Suction flow rates (40–160L min−1) had no effect on the final location of particles in a closed system. Particle removal from within the shield was optimal when a suction catheter was placed vertically next to the head of the patient. Addition of multiple openings in the shield reduced the purging performance from 99% at 160 L min−1 to 67% at 40 L min−1.ConclusionComputational fluid dynamics modelling provides information to guide optimisation of the efficient removal of hazardous pathogens released during AGP from a custom-designed shield. These data are essential to establish before clinical use and/or pragmatic clinical trials.

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