The Numerical Simulation of Turbulent Natural Convection in a Rectangular Enclosure Using K-[epsilon] and K [epsilon]/ASM Turbulence Models PDF Download

Author: Douglas James Silva
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 428

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ISBN:
Category :
Languages : en
Pages :

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A demand for methods that can be used in the numerical analysis of three dimensional air flow in large buildings has developed as more buildings are being designed with large atriums using a solar loading that leads to complex flow. The flow in such buildings is almost always turbulent which means that turbulence models that are accurate but which do not require undue computer resources have to be selected. As a result, a numerical study of natural convective heat transfer and turbulent flows in large atria, specifically part of the Atria in the EV building at Concordia University, has been completed. Experimental work on turbulence modeling and atria design has been studied and compared with the numerical results obtained here to gain confidence in the modeling techniques used in the study. The flow has been assumed to be steady, and the Boussinesq approximation has been used. The governing equations have been numerically solved using the CFD solver FLUENT. The three-dimensional air flow in the Concordia-like atria used the following parameters: forced flow vent inlet angle; forced flow vent velocity; date and time (for solar radiation purposes). The case with adiabatic floor and ceiling conditions was examined and compared to the case with isothermal floor and ceiling conditions. Several models were studied to compare the effect of turbulent modeling in the atria, including the following: (1) K-Epsilon; (2) K-Omega; (3) Detached Eddy Simulation (DES) model; (4) Large Eddy Simulation (LES) model. Further study was completed after it was noted the flow was completely based on natural convection when the velocity of the inlet flow was set to zero. In addition, experimental results were available and this situation was modeled using similar parameters to the work explained above. Comparing these results supported the accuracy of the work done on the Concordia Atrium. Experimental work on the Annex 26 Atrium in Yokohama Japan was also compared to numerical results to g.

Author:
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ISBN:
Category :
Languages : en
Pages : 26

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Author: Howard D. Goodfellow
Publisher: Academic Press
ISBN: 0128167793
Category : Technology & Engineering
Languages : en
Pages : 745

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Industrial Ventilation Design Guidebook, Volume 2: Engineering Design and Applications brings together researchers, engineers (both design and plants), and scientists to develop a fundamental scientific understanding of ventilation to help engineers implement state-of-the-art ventilation and contaminant control technology. Now in two volumes, this reference contains extensive revisions and updates as well as a unique section on best practices for the following industrial sectors: Automotive; Cement; Biomass Gasifiers; Advanced Manufacturing; Industrial 4.0); Non-ferrous Smelters; Lime Kilns; Pulp and Paper; Semiconductor Industry; Steelmaking; Mining. Brings together global researchers and engineers to solve complex ventilation and contaminant control problems using state-of-the-art design equations Includes an expanded section on modeling and its practical applications based on recent advances in research Features a new chapter on best practices for specific industrial sectors

Author: Krishnendu Sinha
Publisher:
ISBN:
Category :
Languages : en
Pages : 436

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Author: T. H. Shih
Publisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 26

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Author: Francis Kimani Gatheri
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 592

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Category :
Languages : en
Pages : 28

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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722011550
Category :
Languages : en
Pages : 24

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A k-epsilon model is proposed for wall bonded turbulent flows. In this model, the eddy viscosity is characterized by a turbulent velocity scale and a turbulent time scale. The time scale is bounded from below by the Kolmogorov time scale. The dissipation equation is reformulated using this time scale and no singularity exists at the wall. The damping function used in the eddy viscosity is chosen to be a function of R(sub y) = (k(sup 1/2)y)/v instead of y(+). Hence, the model could be used for flows with separation. The model constants used are the same as in the high Reynolds number standard k-epsilon model. Thus, the proposed model will be also suitable for flows far from the wall. Turbulent channel flows at different Reynolds numbers and turbulent boundary layer flows with and without pressure gradient are calculated. Results show that the model predictions are in good agreement with direct numerical simulation and experimental data. Yang, Z. and Shih, T. H. Glenn Research Center NASA ORDER C-99066-6; RTOP 505-62-21...

Author: Alexander Kayne
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 57

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In recent years Computational Fluid Dynamics (CFD) simulations are increasingly used to model the air circulation and temperature environment inside the rooms of residential and office buildings to gain insight into the relative energy consumptions of various HVAC systems for cooling/heating for climate control and thermal comfort. This requires accurate simulation of turbulent flow and heat transfer for various types of ventilation systems using the Reynolds-Averaged Navier-Stokes (RANS) equations of fluid dynamics. Large Eddy Simulation (LES) or Direct Numerical Simulation (DNS) of Navier-Stokes equations is computationally intensive and expensive for simulations of this kind. As a result, vast majority of CFD simulations employ RANS equations in conjunction with a turbulence model. In order to assess the modeling requirements (mesh, numerical algorithm, turbulence model etc.) for accurate simulations, it is critical to validate the calculations against the experimental data. For this purpose, we use three well known benchmark validation cases, one for natural convection in 2-D closed vertical cavity, second for forced convection in a 2-D rectangular cavity and the third for mixed convection in a 2-D square cavity. The simulations are performed on a number of meshes of different density using a number of turbulence models. It is found that k-[epsilon] two-equation turbulence model with a second-order algorithm on a reasonable mesh gives the best results. This information is then used to determine the modeling requirements (mesh, numerical algorithm, turbulence model etc.) for flows in 3D enclosures with different ventilation systems. In particular two cases are considered for which the experimental data is available. These cases are (1) air flow and heat transfer in a naturally ventilated room and (2) airflow and temperature distribution in an atrium. Good agreement with the experimental data and computations of other investigators is obtained.