Download or read book Numerical Simulation of the Air Flow Field in a Laboratory Fume Hood Using the CFD ACE TM Computational Fluid Dynamics Code written by Cedric Benedict D'Sousa and published by . This book was released on 1997 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulation of Laboratory Fume Hood Airflow Performance written by Robert Reither and published by . This book was released on 1998 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Computational Fluid Dynamics CFD Simulation of Test Chamber and Smoke Generating Device written by and published by . This book was released on 1995 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: The U.S. Army Research Laboratory (ARL) has completed an initial investigation of the flow field within a typical U.S. Army Edgewood Research, Development, and Engineering Center (ERDEC) test chamber via numerical simulation. The ERDEC test chamber is designed to mix compressor-driven airflow with gas/solid effluent from a test article placed inside the chamber. An example of such a test article is a smoke generator, or smoke pot. Simulation of this flow utilized ARL computational fluid dynamics (CFD) codes that include multispecies chemical kinetics. Numerical solutions of the gas flow and effluent concentration distributions in the test chamber were generated for operating times up to 4.5 min. Numerical simulations reveal that certain values of chamber through-flow induce flow patterns within the chamber that are dominated by rotating vortices. This flow pattern increases the effluent residence time in the chamber as well as the mixing of gas/particulate from the test article with air. As a result, pockets of high effluent concentration can form in the chamber. Graphical results with discussion are presented.

Download or read book Comparison of a 3 D CFD DSMC Solution Methodology With a Wind Tunnel Experiment written by Christopher Earl Glass and published by . This book was released on 2002 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Survey of CFD Applications for High Speed Inlets written by Keith E. Numbers and published by . This book was released on 1994 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive review of techniques and methods for applying computational fluid dynamics (CFD) analysis to high speed inlets and related flows is provided via an extensive literature survey of such applications. Topics covered include governing equations, numerical integration schemes, boundary conditions, gridding requirements, and turbulence models. Results of applications from the literature survey shed light on the relative success of the techniques being used throughout the industry. (AN).

Download or read book Computational Fluid Dynamics CFD Simulations of Aerosol in a U shaped Steam Generator Tube written by Pamela Longmire and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: To quantify primary side aerosol retention, an Eulerian/Lagrangian approach was used to investigate aerosol transport in a compressible, turbulent, adiabatic, internal, wall-bounded flow. The ARTIST experimental project (Phase I) served as the physical model replicated for numerical simulation. Realizable k-æ and standard k- turbulence models were selected from the computational fluid dynamics (CFD) code, FLUENT, to provide the Eulerian description of the gaseous phase. Flow field simulation results exhibited: a) onset of weak secondary flow accelerated at bend entrance towards the inner wall; b) flow separation zone development on the convex wall that persisted from the point of onset; c) centrifugal force concentrated high velocity flow in the direction of the concave wall; d) formation of vortices throughout the flow domain resulted from rotational (Dean-type) flow; e) weakened secondary flow assisted the formation of twin vortices in the outflow cross section; and f) perturbations induced by the bend influenced flow recovery several pipe diameters upstream of the bend. These observations were consistent with those of previous investigators. The Lagrangian discrete random walk model, with and without turbulent dispersion, simulated the dispersed phase behavior, incorrectly. Accurate deposition predictions in wall-bounded flow require modification of the Eddy Impaction Model (EIM). Thus, to circumvent shortcomings of the EIM, the Lagrangian time scale was changed to a wall function and the root-mean-square (RMS) fluctuating velocities were modified to account for the strong anisotropic nature of flow in the immediate vicinity of the wall (boundary layer). Subsequent computed trajectories suggest a precision that ranges from 0.1% to 0.7%, statistical sampling error. The aerodynamic mass median diameter (AMMD) at the inlet (5.5 m) was consistent with the ARTIST experimental findings. The geometric standard deviation (GSD) varied depending on the scenario evaluated but ranged from 1.61 to 3.2. At the outlet, the computed AMMD (1.9 m) had GSD between 1.12 and 2.76. Decontamination factors (DF), computed based on deposition from trajectory calculations, were just over 3.5 for the bend and 4.4 at the outlet. Computed DFs were consistent with expert elicitation cited in NUREG-1150 for aerosol retention in steam generators.

Download or read book Personal Spiritual Liberty written by Herbert V. Mills and published by . This book was released on 1888 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Progress and Challenges in CFD Methods and Algorithms written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development. Fluid Dynamics Panel. Symposium and published by . This book was released on 1996 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Resolution CFD Simulation of Airflow and Tracer Dispersion in New York City written by S. T. Chan and published by . This book was released on 2005 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 2004, a research project--the New York City Urban Dispersion Program (NYC UDP)--was launched by the Department of Homeland Security with the goal to improve the permanent network of wind stations in and around New York City and to enhance the city's emergency response capabilities. Encompassing both field studies and computer modeling, one of the program's objectives is to improve and validate urban dispersion models using the data collected from field studies and to transfer the improved capabilities to NYC emergency agencies. The first two field studies were conducted in March and August 2005 respectively and an additional study is planned for the summer of 2006. Concurrently model simulations, using simple to sophisticated computational fluid dynamics (CFD) models, have been performed to aid the planning of field studies and also to evaluate the performance of such models. Airflow and tracer dispersion in urban areas such as NYC are extremely complicated. Some of the contributing factors are complex geometry, variable terrain, coupling between local and larger scale flows, deep canyon mixing and updrafts/downdrafts caused by large buildings, street channeling and upstream transport, roof features, and heating effects, etc. Sponsored by the U.S. Department of Energy (DOE) and Department of Homeland Security (DHS), we have developed a CFD model, FEM3MP, to address some of the above complexities. Our model is based on solving the three-dimensional, time-dependent, incompressible Navier-Stokes equations with appropriate physics for modeling airflow and dispersion in the urban environment. Also utilized in the model are finite-element discretization for effective treatment of complex geometries and a semi-implicit projection method for efficient time-integration. A description of the model can be found in Gresho and Chan (1998), Chan and Stevens (2000). Predictions from our model are continuously being verified against data from field studies, such as URBAN 2000 and the Joint URBAN 2003 experiments. Modeling studies comparing simulations to observations from these field experiments are discussed in Chan et al. (2001,2004), Chan and Leach (2004), Chan and Lundquist (2005), Humphreys et al. (2004), Lundquist and Chan (2005).

Download or read book Computational Fluid Dynamics CFD Modeling of Mixed Convection Flows in Building Enclosures written by Alexander Kayne and published by . This book was released on 2012 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book A Three Layered Framework for Annual Indoor Airflow CFD Simulation written by Yue Wang and published by . This book was released on 2013 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book CFD Simulation of Heavy Gas Cloud written by and published by . This book was released on 1994 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents a numerical simulation of the process of dispersion in the atmosphere of large quantities of liquefied natural gas vapor (heavy gas) emitted after an accident. The simulation used TASCflow Version 2.3 computational fluid dynamics software, a finite-volume method-based code that solves the three-dimensional Reynolds-averaged conservation equations for the mass, momentum, energy, and chemical species that govern transport processes in complex geometries. The paper contains the results of computation in numerical and graphical form of the time history of the development of the heavy gas concentration, temperature, and flow field. The paper includes description of the main elements of the computational approach employed, such as the grid and the initial and boundary conditions. The modelling results are compared to experimental evidence found in the literature.

Download or read book Computational Fluid Dynamics in Ventilation Design written by and published by . This book was released on 2007 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Coupling of a Multizone Airflow Simulation Program with Computational Fluid Dynamics for Indoor Environmental Analysis written by Yang Gao and published by . This book was released on 2002 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current design of building indoor environment comprises macroscopIC approaches, such as CONT AM multizone airflow analysis tool, and microscopic approaches that apply Computational Fluid Dynamics (CFD). Each has certain advantages and shortfalls in terms of indoor airflow simulation. A coupling approach that combines multizone airflow analysis and detailed CFD airflow modeling would provide complementary information of a building and make results more accurate for practical design. The present study attempted to integrate such building simulation tools in order to better represent the complexity of the real world. The overall objective of this study was to couple an in-house CFD program, MIT-CFD, with a multizone airflow analysis program, CONT AM. Three coupling strategies were introduced. The virtual coupling makes use of the CFD simulation results in a large scale to provide boundary conditions for CONT AM. The quasi-dynamic strategy assumes that CFD can produce a "true" flow pattern and the CONTAM results should be changed accordingly. The dynamic coupling realizes an active two-way interaction between CFD and CONTAM through a bisection search procedure designed by the author that forces the airflow rates from the two models to converge. Various case studies were conducted to validate the coupling strategies. Preliminary results show that all three coupling schemes can result in more reliable airflow patterns. Further investigations are needed to improve the coupling procedures and to apply to more generalized and complex real-world cases.

Download or read book CFD Analysis of Airflow Patterns in High Mining Areas of Room and pillar Coal Mining written by Ahmad Zharif Md Azmi and published by . This book was released on 2014 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis studies airflow patterns in the face area of a typical room-and-pillar mining area, using Computational Fluid Dynamics (CFD) modeling. This research is designed to develop a scientific understanding of airflow distribution in room-and-pillar mining areas that is fundamental to developing engineering controls. The overall goal of the study is to develop improved engineering controls to minimize dust exposure of mine workers in the face area. Dust exposure can be a health hazard in underground coal mining industry based on historical data of coal workers' pneumoconiosis among underground mine workers. Current regulatory dust exposure standards of 1.5 mg/m 3 , averaged over an 8-hour period, have been recently revised with approval of new MSHA standards in April of 2014. Mining companies are currently seeking new technologies in order to comply with the new dust standards. Since mining geometries are complex and do not lend themselves to closed-form analytical solutions, CFD numerical modeling approach was used to develop an understanding of airflow distribution in the face areas. Since previous studies had focused on some cuts in mining heights of less than 2.4 m (8-ft), this study was performed for high mining areas of 4.2 m (14-ft). Such mining heights are very common in longwall mine development areas, particularly in the State of Illinois. The primary goal was to identify major differences in airflow between the two mining heights and how they affect development of engineering controls for minimizing dust exposure. Simulations were done using ANSYS software such as DesignModeler for modeling and meshing and FLUENT for calculations. Recirculation (RC) and low air velocity (LAV) zones were located for straight deep cut, straight deepest cut, cross-cut right, cross-cut right mine through, left turn cross-cut, and left turn cross-cut mine through for low mining height (LMH) and high mining height (HMH) with varying air quantity at the end of the line curtain (ELC). Air at the ELC was adjusted to achieve a ratio of 0.85, 1.00 and 1.15 over the wet scrubber fan (WSF) discharge capacity. Results show that the air velocity in HMH case is much lower than for the LMH. In addition, the location of RC and LAV zones differ based on mining height and air quantity at the ELC. Furthermore, lower air quantity at the ELC causes the air exhausted by the WSF to recirculate back to the face area in order to satisfy the WSF requirement. Recommendations to deal with these differences are formulated.

Download or read book A Computational Fluid Dynamics Study of Incomplete Air Mixing in a Model Slot ventilated Enclosure written by Alain Normand Rousseau and published by Ann Arbor, Mich. : University Microfilms International. This book was released on 1995 with total page 650 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Performance Optimization of Numerical Simulations of Heat Transfer and Fluid Flow written by Matt Blomquist and published by . This book was released on 2019 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical methods to simulate heat transfer and fluid flow phenomena. These numerical simulations require the solution of large linear algebraic systems that arise from the discretization of governing equations and the number of nodes in the discretized mesh is directly related to the accuracy of the simulation. A finer mesh, one with more nodes, will result in better numerical accuracy. However, the computational resources required to solve the linear systems and the overall solution time of the simulation increases with an increased number of nodes. As practitioners continue to develop more complex simulations that require fine meshes, the need for better methods to solve linear systems becomes particularly important. In recent years, there have been significant advancements in computational hardware that have enabled massive parallelism. Multicore processors, graphics processing units, and increased memory capacity have all lead way to significant performance increases for high-performance computing (HPC) workflows that allow for faster and more accurate numerical simulations. However, many of the legacy algorithms used to solve the linear systems in CFD are not well suited to exploit the parallelism in modern computational hardware. Krylov-subspace methods are an ideal solution to this problem as the Krylov algorithms can be parallelized through single-instruction, multiple data (SIMD) operations. In the current study, the Krylov-subspace methods of Bi-Conjugate Gradients, Generalized Minimum Residual, Bi-Conjugate Gradients Stabilized, and Bi-Conjugate Gradients Stabilized (l) are examined as potential algorithms to improve the solution time for numerical simulations of heat transfer and fluid flow. Each of the Krylov methods will be characterized against the standard, line-by-line Tri-Diagonal Matrix Algorithm using a heat conduction model and a Rayleigh-Bénard Convection model. The numerical experiments using heat conduction will examine the impact of grid size and boundary condition placement for each of the algorithms tested. The Rayleigh-Bénard Convection model will be used to determine the performance improvements of the Krylov methods in Patankar's SIMPLER algorithm. The numerical accuracies of each algorithm will be validated using analytical solutions for the heat conduction model and empirical correlations for the Rayleigh-Bénard Convection model.