A CFD Simulation of Strouhal Number for U-Shaped Section Aqueducts

2012 ◽  
Vol 204-208 ◽  
pp. 4738-4741
Author(s):  
Yu Chun Li ◽  
Xiao Jie Zhang ◽  
Shi Wen Jia
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Reynolds Number ◽  
Strouhal Number ◽  
Turbulence Model ◽  
Cfd Simulation ◽  
Reynolds Numbers ◽  
Vortex Induced Vibration ◽  
Computational Fluid Dynamics Cfd ◽  
Shaped Section

The method of computational fluid dynamics (CFD, Fluent code) was applied to simulate the Strouhal numbers of the empty and fulfilled U-shaped sections. Based on the N-S equation and k-ε turbulence model, the effects of Reynolds numbers and height/width ratios of the sections on the Strouhal numbers were investigated. The results of this study show that the Reynolds number has little influence on the Strouhal numbers, which decrease with the increase of height/width ratios of the sections. The conclusion of present study provides a foundation for the further study of vortex-induced vibration of U-shaped aqueduct bridges.

Effect of Baffle Opening Position to the Flow Distribution in a Servco Fume Cupboard

2013 ◽  
Vol 465-466 ◽  
pp. 566-570 ◽  
Author(s):  
Mohd Amal Asrol Omar ◽  
Wirachman Wisnoe ◽  
Azman Bakri
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulence Model ◽  
Cross Sections ◽  
Recirculation Zone ◽  
Cfd Simulation ◽  
Flow Distribution ◽  
Recirculation Region ◽  
Potential Contributor ◽  
Computational Fluid Dynamics Cfd

From the computational fluid dynamics (CFD) simulation of Servco fume cupboard using κ-ω turbulence model, it is found that recirculation region behind the sash is the potential contributor to the leakage of the contaminants due to its large size. To have a good fume cupboard, the recirculation zone needs to be minimised while maintaining the flow distributions to all area in the fume cupboard. The opening on the baffle may reduce the recirculation zone which in turn may reduce back flow that can be the cause of leakage. In this paper, the effect of baffle openings on flow distributions of a Servco fume cupboard will be presented as a result of computational fluid dynamics (CFD) simulation using κ-ω turbulence model. The results are presented in terms of magnitude of curl of velocity vectors Vxyzat different cross sections of the fume cupboard for 4 variations of location of baffles opening.

scholarly journals Thermoelectric Generation with Impinging Nano-Jets

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 492
Author(s):  
Fatih Selimefendigil ◽  
Hakan F. Oztop ◽  
Mikhail A. Sheremet
Keyword(s):  
Fluid Dynamics ◽  
Power Generation ◽  
Computational Fluid Dynamics ◽  
Reynolds Number ◽  
Conversion Efficiency ◽  
Reynolds Numbers ◽  
Thermoelectric Generation ◽  
Volume Fractions ◽  
Water Jets ◽  
Conversion Efficiencies

In this study, thermoelectric generation with impinging hot and cold nanofluid jets is considered with computational fluid dynamics by using the finite element method. Highly conductive CNT particles are used in the water jets. Impacts of the Reynolds number of nanojet stream combinations (between (Re1, Re2) = (250, 250) to (1000, 1000)), horizontal distance of the jet inlet from the thermoelectric device (between (r1, r2) = (−0.25, −0.25) to (1.5, 1.5)), impinging jet inlet to target surfaces (between w2 and 4w2) and solid nanoparticle volume fraction (between 0 and 2%) on the interface temperature variations, thermoelectric output power generation and conversion efficiencies are numerically assessed. Higher powers and efficiencies are achieved when the jet stream Reynolds numbers and nanoparticle volume fractions are increased. Generated power and efficiency enhancements 81.5% and 23.8% when lowest and highest Reynolds number combinations are compared. However, the power enhancement with nanojets using highly conductive CNT particles is 14% at the highest solid volume fractions as compared to pure water jet. Impacts of horizontal location of jet inlets affect the power generation and conversion efficiency and 43% variation in the generated power is achieved. Lower values of distances between the jet inlets to the target surface resulted in higher power generation while an optimum value for the highest efficiency is obtained at location zh = 2.5ws. There is 18% enhancement in the conversion efficiency when distances at zh = ws and zh = 2.5ws are compared. Finally, polynomial type regression models are obtained for estimation of generated power and conversion efficiencies for water-jets and nanojets considering various values of jet Reynolds numbers. Accurate predictions are obtained with this modeling approach and it is helpful in assisting the high fidelity computational fluid dynamics simulations results.

scholarly journals Computational Fluid Dynamics (CFD) Simulation on Mixing in T-Shaped Micromixer

2020 ◽  
Vol 932 ◽  
pp. 012006
Author(s):  
S N A Ahmad Termizi ◽  
C Y Khor ◽  
M A M Nawi ◽  
Nurlela Ahmad ◽  
Muhammad Ikman Ishak ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Computational Fluid Dynamics Cfd

Analysis of an Airfoil Using a Transition and Turbulence Model

2016 ◽  
Vol 819 ◽  
pp. 356-360
Author(s):  
Mazharul Islam ◽  
Jiří Fürst ◽  
David Wood ◽  
Farid Nasir Ani
Keyword(s):  
Fluid Dynamics ◽  
Boundary Layer ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Turbulence Model ◽  
Original Version ◽  
Transitional Region ◽  
Cfd Analysis ◽  
Computational Fluid Dynamics Cfd

In order to evaluate the performance of airfoils with computational fluid dynamics (CFD) tools, modelling of transitional region in the boundary layer is very critical. Currently, there are several classes of transition-based turbulence model which are based on different methods. Among these, the k-kL- ω, which is a three equation turbulence model, is one of the prominent ones which is based on the concept of laminar kinetic energy. This model is phenomenological and has several advantageous features. Over the years, different researchers have attempted to modify the original version which was proposed by Walter and Cokljat in 2008 to enrich the modelling capability. In this article, a modified form of k-kL-ω transitional turbulence model has been used with the help of OpenFOAM for an investigative CFD analysis of a NACA 4-digit airfoil at range of angles of attack.

A Study on the Performance of Stratified Air Conditioning Design in Assembly Halls – A Case Study at the Dazhi Cultural Center in Taiwan

2013 ◽  
Vol 368-370 ◽  
pp. 599-602 ◽  
Author(s):  
Ian Hung ◽  
Hsien Te Lin ◽  
Yu Chung Wang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Indoor Air ◽  
Air Conditioning ◽  
Cfd Simulation ◽  
Indoor Temperature ◽  
Cultural Center ◽  
Computational Fluid Dynamics Cfd

This study focuses on the performance of air conditioning design at the Dazhi Cultural Center and uses a computational fluid dynamics (CFD) simulation to discuss the differences in wind velocity and ambient indoor temperature between all-zone air conditioning design and stratified air conditioning design. The results have strong implications for air conditioning design and can improve the indoor air quality of assembly halls.

Design Approach for the Development of the Flow Field of Bipolar Plates for a PEMFC Stack Prototype

2014 ◽  
Vol 11 (6) ◽  
Author(s):  
Paolo Sala ◽  
Paola Gallo Stampino ◽  
Giovanni Dotelli
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fuel Cell ◽  
Cfd Simulation ◽  
Bipolar Plates ◽  
Flow Rates ◽  
Gas Leakage ◽  
Auxiliary Power ◽  
Computational Fluid Dynamics Cfd ◽  
Enhance Mass

This work is part of a project whose final aim is the realization of an auxiliary power fuel cell generator. It was necessary to design and develop bipolar plates that would be suitable for this application. Bipolar plates have a relevant influence on the final performances of the entire device. A gas leakage or a bad management of the water produced during the reaction could be determinant during operations and would cause the failure of the stack. The development of the bipolar plates was performed in different steps. First, the necessity to make an esteem of the dynamics that happen inside the feeding channels led to perform analytical calculations. The values found were cross-checked performing a computational fluid dynamics (CFD) simulation; finally, it was defined the best pattern for the feeding channels, so that to enhance mass transport and achieve the best velocity profile. The bipolar plates designed were machined and assembled in a laboratory scale two cells prototype stack. Influences of the temperature and of the humidity were evaluated performing experiments at 60 deg and 70 deg and between 60% and 100% of humidity of the reactant gasses. The best operating point achieved in one of these conditions was improved by modifying the flow rates of the reactant, in order to obtain the highest output power, and it evaluated the reliability of the plates in experiments performed for longer times, at fixed voltages.

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