Field testing CFD-based predictions of storage chamber gross solids separation efficiency

1999 ◽  
Vol 39 (9) ◽  
pp. 161-168 ◽  
Author(s):  
Virginia R. Stovin ◽  
Adrian J. Saul ◽  
Andrew Drinkwater ◽  
Ian Clifforde
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Settling Velocity ◽  
Separation Efficiency ◽  
Flow Patterns ◽  
Total Efficiency ◽  
Separation Performance ◽  
Storage Chamber ◽  
Solids Separation ◽  
Simulated Flow

The use of computational fluid dynamics-based techniques for predicting the gross solids and finely suspended solids separation performance of structures within urban drainage systems is becoming well established. This paper compares the result of simulated flow patterns and gross solids separation predictions with field measurements made in a full size storage chamber. The gross solids retention efficiency was measured for six different storage chambers in the field and simulations of these chambers were undertaken using the Fluent computational fluid dynamics software. Differences between the observed and simulated flow patterns are discussed. The simulated flow fields were used to estimate chamber efficiency using particle tracking. Efficiency results are presented as efficiency cusps, with efficiency plotted as a function of settling velocity. The cusp represents a range of efficiency values, and approaches to the estimation of an overall efficiency value from these cusps are briefly discussed. Estimates of total efficiency based on the observed settling velocity distribution differed from the measured values by an average of ±17%. However, estimates of steady flow efficiency were consistently higher than the observed values. The simulated efficiencies agreed with the field observations in identifying the most efficient configuration.

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.

Abstract 20526: Computational Fluid Dynamics in Partial Mechanical Circulatory Support: Implications for Patient Care

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Sasan Partovi ◽  
Christoph Karmonik ◽  
Fabian Rengier ◽  
Matthias Mueller-Eschner ◽  
Hagen Meredig ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Heart Failure ◽  
Computational Fluid Dynamics ◽  
Mechanical Circulatory Support ◽  
Cardiac Cycle ◽  
Heart Function ◽  
Innominate Artery ◽  
Flow Patterns ◽  
Flow Reversal ◽  
Circulatory Support

Introduction: Partial mechanical circulatory support (pMCS) is used for the therapy of heart failure. The CircuLite® Pump has been introduced clinically with its inflow cannula connected to the left atrium and the outflow cannula to the right subclavian artery. Aim of our study was to visualize and quantify flow patterns using computational fluid dynamics (CFD) in CT angiography (CTA). Methods: Two heart failure patients with pMCS were imaged with ECG-gated CTA and echocardiography. CFD was performed in 3D derived from CTA using flow boundary conditions measured with ultrasound. Flow was visualized using velocity vectors of blood flow. Average velocity was calculated at 10 time points during cardiac cycle in the aorta and the innominate. Wall shear stress (WSS) was visualized on the wall of the digital model. Results: Flow reversal was observed in mid-systole for both cases distal from the origin of the innominate artery in both cases due to asynchrony of the constant flow of the device with the pulsatile flow of the heart (fig.). Maximum velocity of this back flow was 0.39 m/s in case 1 and 0.2 m/s in case 2. Therefore, further distal in the innominate artery, a region of slow and stagnant flow with low WSS at the artery wall was observed which changed during cardiac cycle. Conclusions: CFD analysis revealed an asynchronous behavior in the inducted flow patterns during systole. Further design should allow for synchronization with the native heart function. Figure: On top flow during systole for both cases (case 1 on left), below flow during diastole. WSS is shown in pseudo-color representation with red indicating high values. Flow is visualized by arrows. During systole, a region of low WSS (blue) exists in the innominate artery which is absent during systole indicating flow reversal at this location. Bottom panel: Velocity in inferior-superior direction during cardiac cycle for both cases. Red lines demonstrates change of direction of flow in the innominate during systole.

Study of the Particle Separation Performance of a Dust-settling Hopper

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Bofu Wu ◽  
Jinlai Men ◽  
Jie Chen
Keyword(s):  
Fluid Dynamics ◽  
Particle Concentration ◽  
Separation Efficiency ◽  
Simulation Analysis ◽  
Numerical Study ◽  
Particle Separation ◽  
Separation Performance ◽  
Particle Removal ◽  
Airflow Velocity ◽  
Calculation Results

This paper presents a numerical study to predict the particle separation performance of a dust-settling hopper using computational fluid dynamics. The Euler-Lagrange approach was employed to analyze the particle separation efficiency and the outflow particle concentration of the dust-settling hopper under different inlet airflow velocities. The calculation results obtained reveal that the overall particle separation efficiency and the outflow particle concentration decrease with the increase of the inlet airflow velocity, and the particle grade efficiency increases with particle size. Since there is a paradox between the particle separation performance and the particle removal performance for a street vacuum sweeper, it is necessary to counter-balance the effects of the inlet airflow velocity on them. According to the simulation analysis, an appropriate inlet airflow velocity is provided for the design of the dust-settling hopper.

scholarly journals O-033 Jugular Vein Flow Patterns in Patients with Pulsatile Tinnitus Using Computational Fluid Dynamics

2016 ◽  
Vol 8 (Suppl 1) ◽  
pp. A22.1-A22
Author(s):  
E Kao ◽  
S Kefayati ◽  
K Meisel ◽  
M Ballweber ◽  
F Faraji ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Jugular Vein ◽  
Flow Patterns ◽  
Pulsatile Tinnitus

Practical Learning on Computational Fluid Dynamics at Undergraduate Level

2016 ◽  
Author(s):  
Teresa Parra-Santos ◽  
José M. Molina Jordá ◽  
Gabriel Luna-Sandoval ◽  
Mariano Cacho-Perez ◽  
J. Rubén Pérez
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Engineering Students ◽  
Active Role ◽  
Flow Patterns ◽  
Industrial Applications ◽  
Similar Degree ◽  
Test Cases ◽  
Critical Thought ◽  
Grid Points

This work involves a methodology for Mechanical Engineering students to learn Computational Fluid Dynamics playing an active role. Students carry out a fluid mechanics down scaled projects with the steps of sensibility of mesh, convergence of numerical algorithm, validation of turbulence model and description of flow patterns. Furthermore, they develop their critical thought when they identify weak points susceptible for improvement. The offer of benchmark test cases ranges from head loses, driven cavities, swirling flows, to external aerodynamics. Simplifications to the level of undergraduate courses imply two dimensional simulations and a limited number of grid points. Hence, the assessment is based in coherence of decisions and efficient use of limited resources. A review of the offer of workshops is supplied, such as the Ahmed car, the Roback and Johnson burner, aerodynamics of different NACA airfoils, and different geometries of driven cavities. These are classical test cases of numerical research and a sample of applications in wind energy, industrial furnaces, and lubrication. Parametrization based in geometry, Reynolds number, Pitch angle among other, let simulate different flow patterns with similar degree of difficulty. There is a deeper understanding of the topic when students need to discuss the strategies to accomplish the project, they need to write a technical report and finally they need to justify the evaluation of other works. Also, it is important to link the simplified projects of the workshop with the real world and the industrial applications.

Computational Fluid Dynamics modelling of sedimentation on Mars

2020 ◽  
Author(s):  
Nikolaus J. Kuhn ◽  
Federica Trudu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Gravitational Force ◽  
Settling Velocity ◽  
Cfd Modelling ◽  
Running Water ◽  
Sediment Sorting ◽  
Computational Fluid Dynamics Cfd ◽  
Dynamics Modelling ◽  
Laminar State

<p>Gravity affects sedimentation of particles suspended in water and gases in two ways: directly by the gravitational force that pulls a particle towards the surface and indirectly by the flow conditions of water or gas around the particles. The latter create a drag which is affected by the settling velocity. Consequently, drag coefficients observed on Earth sand-sized particles cannot be used on Mars because they are likely to overestimate the drag generated by the turbulent flow around the particle on Earth may shift into a more laminar state that generates lower drag. The effect of gravity on settling velocity is not linearly related to particle size, which may affect the sorting of the sand grains deposited from running water.  Experiments carried out during parabolic flights at reduced gravity indicate that the potential error in particle settling and sorting is significant, i.e. leading to wrong interpretations of the flow velocities at the time of deposition. This in turn has implications for reconstruction of Martian environmental conditions from rock textures determined from close-up imagery. This study uses computational fluid dynamics (CFD) modelling to independently assess the effect of gravity on sediment settling velocities and sediment sorting. The CFD modelling also offers a wide capability for reconstruction sedimentation on Mars and thus supports the reconstruction of it’s environmental past, as well as the search for traces of life. </p>

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