Integration of the Nek5000 Computational Fluid Dynamics Code to the NEAMS Workbench: Modeling of the Turbulent Flow in a High-Flux Isotope Reactor Channel

2019 ◽  
Author(s):  
M. Baird ◽  
M. Delchini ◽  
R. Lefebvre ◽  
P. Miller ◽  
W. Pointer
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulent Flow ◽  
High Flux ◽  
Reactor Channel

Computational Fluid Dynamics Techniques for Flows in Lapple Cyclone Separator

2005 ◽  
Vol 498-499 ◽  
pp. 179-185
Author(s):  
A.F. Lacerda ◽  
Luiz Gustavo Martins Vieira ◽  
A.M. Nascimento ◽  
S.D. Nascimento ◽  
João Jorge Ribeiro Damasceno ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Turbulent Flow ◽  
Reynolds Stress ◽  
Cyclone Separator ◽  
Two Dimensional ◽  
Stress Components ◽  
Computational Fluid Dynamics Cfd

A two-dimensional fluidynamics model for turbulent flow of gas in cyclones is used to evaluate the importance of the anisotropic of the Reynolds stress components. This study presents consisted in to simulate through computational fluid dynamics (CFD) package the operation of the Lapple cyclone. Yields of velocity obtained starting from a model anisotropic of the Reynolds stress are compared with experimental data of the literature, as form of validating the results obtained through the use of the Computational fluid dynamics (Fluent). The experimental data of the axial and swirl velocities validate numeric results obtained by the model.

Computational Fluid Dynamics Analysis of Two Parallel Rectangular Jets Using OpenFOAM

2016 ◽  
Author(s):  
Han Li ◽  
Huhu Wang ◽  
Yassin A. Hassan ◽  
N. K. Anand
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulent Flow ◽  
Stokes Equations ◽  
Laser Doppler Anemometry ◽  
Physical Models ◽  
Shear Stresses ◽  
Turbulence Characteristic ◽  
Computational Fluid Dynamics Analysis ◽  
Simulation Results

Two or multiple parallel jets are an important shear flow that widely existing in many industrial applications. The interaction between turbulence jets enables fast and thorough mixing of two fluids. The mixing feature of parallel jets has many engineering applications, such as, in Generation IV conceptual nuclear reactors, the coolants merge in upper or lower plenum after passing through the reactor core. While study of parallel jets mixing phenomenon, numerical experiments such as Computational Fluid Dynamics (CFD) simulations are extensively incorporated. Validation of varied turbulent models is of importance to make sure that the numerical results could be trusted and served as a guideline further design purpose. Many commercial CFD packages in the market such as FLUENT and Star CCM+ can provide the ability to simulate turbulent flow with predefined turbulence model, however, such commercial solvers may lack the flexibility that allow users build their own models for R&D purpose. The existing solvers in OpenFOAM are developed to fulfill both academic and industrial needs by achieving large-scale computational capability with a variety of physical models. Moreover, as an open source CFD toolbox, OpenFOAM grants users full control of the source code with complete freedom of customization. The purpose of this study is to perform CFD simulation using OpenFOAM for two submerged parallel jets issuing from two rectangular channels. Fully hexahedron multi-density mesh is generated using blockMesh utility to ensure velocity gradients are properly evaluated. A generalized-multi-grid solver is used to enhance convergence. Based on Reynolds-Averaged Navier-Stokes Equations (RANS), the realizable k-ε and k-ε shear stress transport (SST) are selected to model turbulent flow. Steady state Finite Volume solver simpleFoam is used to perform the simulation. In addition, data from experiments run in Thermal-Hydraulic Lab at Texas A&M University using particle image velocity (PIV) and Laser Doppler Anemometry (LDA) methods are considered in order to compare and validate simulation results. A number of turbulence characteristic such as mean velocities, turbulent intensities, z-component vorticity were compared with experiments. It was found that for stream-wise mean velocity profile as well as shear stresses, the realizable k-ε model exhibits a good agreement with experimental data. However, velocity fluctuation and turbulence intensities, simulation results showed a certain discrepancy.

scholarly journals The benefits of turbine endwall profiling in a cascade

2005 ◽  
Vol 219 (1) ◽  
pp. 49-59 ◽  
Author(s):  
G Ingram ◽  
D Gregory-Smith ◽  
N Harvey
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulent Flow ◽  
Secondary Flow ◽  
Surface Flow ◽  
Transitional Flow ◽  
Loss Reduction ◽  
Small Reduction ◽  
Laminar And Turbulent Flow ◽  
Computational Fluid Dynamics Cfd

Non-axisymmetric profiled endwalls have been shown to reduce losses and secondary flow both in cascades and in rig tests. This paper presents experimental results which quantify the benefits of loss reduction in the cascade with particular attention to accuracy. The paper compares the benefits achieved in experiment to the results predicted by computational fluid dynamics (CFD). The results show that both the experiment and CFD give significant reductions in secondary flow. A reduction of 31 per cent in secondary loss has been measured for the best case, but the CFD gives only a small reduction in loss. Previous studies on the planar endwall have shown significant areas of transitional flow, so the surface flow has been studied with the aid of surface-mounted hot films. It was concluded that the loss reductions were not due to changes in regions of laminar and turbulent flow.

Multilaboratory Particle Image Velocimetry Analysis of the FDA Benchmark Nozzle Model to Support Validation of Computational Fluid Dynamics Simulations

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Prasanna Hariharan ◽  
Matthew Giarra ◽  
Varun Reddy ◽  
Steven W. Day ◽  
Keefe B. Manning ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Particle Image Velocimetry ◽  
Turbulent Flow ◽  
Medical Device ◽  
Particle Image ◽  
Transitional Flow ◽  
Flow Conditions ◽  
Image Velocimetry ◽  
Flow Case

This study is part of a FDA-sponsored project to evaluate the use and limitations of computational fluid dynamics (CFD) in assessing blood flow parameters related to medical device safety. In an interlaboratory study, fluid velocities and pressures were measured in a nozzle model to provide experimental validation for a companion round-robin CFD study. The simple benchmark nozzle model, which mimicked the flow fields in several medical devices, consisted of a gradual flow constriction, a narrow throat region, and a sudden expansion region where a fluid jet exited the center of the nozzle with recirculation zones near the model walls. Measurements of mean velocity and turbulent flow quantities were made in the benchmark device at three independent laboratories using particle image velocimetry (PIV). Flow measurements were performed over a range of nozzle throat Reynolds numbers (Rethroat) from 500 to 6500, covering the laminar, transitional, and turbulent flow regimes. A standard operating procedure was developed for performing experiments under controlled temperature and flow conditions and for minimizing systematic errors during PIV image acquisition and processing. For laminar (Rethroat=500) and turbulent flow conditions (Rethroat≥3500), the velocities measured by the three laboratories were similar with an interlaboratory uncertainty of ∼10% at most of the locations. However, for the transitional flow case (Rethroat=2000), the uncertainty in the size and the velocity of the jet at the nozzle exit increased to ∼60% and was very sensitive to the flow conditions. An error analysis showed that by minimizing the variability in the experimental parameters such as flow rate and fluid viscosity to less than 5% and by matching the inlet turbulence level between the laboratories, the uncertainties in the velocities of the transitional flow case could be reduced to ∼15%. The experimental procedure and flow results from this interlaboratory study (available at http://fdacfd.nci.nih.gov) will be useful in validating CFD simulations of the benchmark nozzle model and in performing PIV studies on other medical device models.

Flow over a glider canopy

2014 ◽  
Vol 118 (1204) ◽  
pp. 669-682
Author(s):  
A. S. Jonker ◽  
J. J. Bosman ◽  
E. H. Mathews ◽  
L. Liebenberg
Keyword(s):  
Fluid Dynamics ◽  
Boundary Layer ◽  
Computational Fluid Dynamics ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Aerodynamic Drag ◽  
Canopy Gap ◽  
Experimental Investigations ◽  
Front Part ◽  
Gap Width

Abstract In order to minimise drag, the front part of most modern glider fuselages is shaped so that laminar flow is preserved to a position close to the wing-to-fuselage junction. Experimental investigations on a full-scale JS1 competition glider however revealed that the laminar boundary layer in fact trips to turbulent flow at the fuselage-to-canopy junction position, increasing drag. This is possibly due to ventilation air leaking from the cockpit to the fuselage surface through the canopy seal, or that the gap is merely too large and therefore trips the boundary layer to turbulent flow. The effect of air leaking from the fuselage-to-canopy gap as well as the size of the gap was thus investigated with the use of computational fluid dynamics. It was found that if air was leaking through this gap the boundary layer would be tripped from laminar to turbulent flow. It was also found that the width of the canopy-to-fuselage gap plays a significant role in the preservation of laminar flow. If the gap is less than 1mm wide, the attached boundary layer is able to negotiate the gap without being tripped to turbulent flow, while if the gap is 3mm and wider, it will be tripped from laminar to turbulent flow. The work shows that aerodynamic drag on a glider can be significantly minimised by completely sealing the fuselage-to-canopy gap and by ensuring a seal gap-width of less than 1mm.

scholarly journals Teaching turbulent flow through pipe fittings using computational fluid dynamics approach

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Bhavesh D. Gajbhiye ◽  
Harshawardhan A. Kulkarni ◽  
Shashank S. Tiwari ◽  
Channamallikarjun S. Mathpati
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulent Flow ◽  
Flow Through ◽  
Pipe Fittings

Four-dimensional flow MRI for evaluation of post-stenotic turbulent flow in a phantom: comparison with flowmeter and computational fluid dynamics

2016 ◽  
Vol 26 (10) ◽  
pp. 3588-3597 ◽  
Author(s):  
Jihoon Kweon ◽  
Dong Hyun Yang ◽  
Guk Bae Kim ◽  
Namkug Kim ◽  
MunYoung Paek ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulent Flow ◽  
Dimensional Flow ◽  
Flow Mri

Computer Aided Simulation of Turbulent Flow in Pulsate Jet Nozzle

1994 ◽  
Author(s):  
Zheng Li ◽  
E. S. Geskin
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulent Flow ◽  
Numerical Solution ◽  
Flow Characteristics ◽  
Helmholtz Resonator ◽  
Nozzle Design ◽  
Turbulent Model ◽  
Computer Aided ◽  
Jet Nozzle

Abstract In this paper, the method of computational fluid dynamics are employed for examination of the formation of a pulsate turbulent waterjet in a Helmholtz resonator type nozzle. The analysis is based on the numerical solution of the conservation equations of mass and momentum, and the standard k-ε turbulent model. The evaluation of the flow characteristics within the nozzle is carried out. Also, the experiments show substantial advantages of this nozzle over a conventional waterjet as a machining tool. The end results of this work will be a knowledge necessary for the improvement of nozzle design and better formation of water and slurry jet.

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