Download or read book Development and Validation of Turbulence Models Through Experiment and Computation written by Torbjörn Sjögren and published by . This book was released on 1997 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Turbulence Modeling Validation Testing and Development written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-17 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary objective of this work is to provide accurate numerical solutions for selected flow fields and to compare and evaluate the performance of selected turbulence models with experimental results. Four popular turbulence models have been tested and validated against experimental data often turbulent flows. The models are: (1) the two-equation k-epsilon model of Wilcox, (2) the two-equation k-epsilon model of Launder and Sharma, (3) the two-equation k-omega/k-epsilon SST model of Menter, and (4) the one-equation model of Spalart and Allmaras. The flows investigated are five free shear flows consisting of a mixing layer, a round jet, a plane jet, a plane wake, and a compressible mixing layer; and five boundary layer flows consisting of an incompressible flat plate, a Mach 5 adiabatic flat plate, a separated boundary layer, an axisymmetric shock-wave/boundary layer interaction, and an RAE 2822 transonic airfoil. The experimental data for these flows are well established and have been extensively used in model developments. The results are shown in the following four sections: Part A describes the equations of motion and boundary conditions; Part B describes the model equations, constants, parameters, boundary conditions, and numerical implementation; and Parts C and D describe the experimental data and the performance of the models in the free-shear flows and the boundary layer flows, respectively. Bardina, J. E. and Huang, P. G. and Coakley, T. J. Ames Research Center...

Download or read book Engineering Turbulence Modelling and Experiments 4 written by D. Laurence and published by Elsevier. This book was released on 1999-04-14 with total page 975 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings contain the papers presented at the 4th International Symposium on Engineering Turbulence Modelling and Measurements held at Ajaccio, Corsica, France from 24-26 May 1999. It follows three previous conferences on the topic of engineering turbulence modelling and measurements. The purpose of this series of symposia is to provide a forum for presenting and discussing new developments in the area of turbulence modelling and measurements, with particular emphasis on engineering-related problems. Turbulence is still one of the key issues in tackling engineering flow problems. As powerful computers and accurate numerical methods are now available for solving the flow equations, and since engineering applications nearly always involve turbulence effects, the reliability of CFD analysis depends more and more on the performance of the turbulence models. Successful simulation of turbulence requires the understanding of the complex physical phenomena involved and suitable models for describing the turbulent momentum, heat and mass transfer. For the understanding of turbulence phenomena, experiments are indispensable, but they are equally important for providing data for the development and testing of turbulence models and hence for CFD software validation.

Download or read book Turbulence Modeling Validation Testing and Development written by and published by . This book was released on 1997 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling Complex Turbulent Flows written by Manuel D. Salas and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulence modeling both addresses a fundamental problem in physics, 'the last great unsolved problem of classical physics,' and has far-reaching importance in the solution of difficult practical problems from aeronautical engineering to dynamic meteorology. However, the growth of supercom puter facilities has recently caused an apparent shift in the focus of tur bulence research from modeling to direct numerical simulation (DNS) and large eddy simulation (LES). This shift in emphasis comes at a time when claims are being made in the world around us that scientific analysis itself will shortly be transformed or replaced by a more powerful 'paradigm' based on massive computations and sophisticated visualization. Although this viewpoint has not lacked ar ticulate and influential advocates, these claims can at best only be judged premature. After all, as one computational researcher lamented, 'the com puter only does what I tell it to do, and not what I want it to do. ' In turbulence research, the initial speculation that computational meth ods would replace not only model-based computations but even experimen tal measurements, have not come close to fulfillment. It is becoming clear that computational methods and model development are equal partners in turbulence research: DNS and LES remain valuable tools for suggesting and validating models, while turbulence models continue to be the preferred tool for practical computations. We believed that a symposium which would reaffirm the practical and scientific importance of turbulence modeling was both necessary and timely.

Download or read book Development of a Turbulent Separated Flow Validation Test Case written by Madeline Cary Samuell and published by . This book was released on 2020 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new validation test case for CFD of turbulent separated flows is investigated through a combination of experiments and simulations. This work is part of an ongoing collaboration between the University of Washington and Boeing, which aims to contribute to the development of a high-quality validation test case for turbulent separated flows and the improvement of RANS modeling for turbulent separated flows. A three-dimensional speed-bump-like geometry, which causes separation as a result of the surface curvature, was chosen for this study. Tests were conducted to determine the influence of Reynolds number and confinement on the flowfield and to test the ability of common RANS turbulence models to accurately predict the flow. Experimental data was used to formalize the required inflow length so that the bump inflow matched between the simulations and experiments. The parameter used to match the inflows was the Reynolds number based on momentum thickness, Re theta, of the incoming boundary layer. The experimental data collected from the incoming boundary layer was also used to prove that the flow upstream of the bump was fully turbulent for all levels of confinement. Five Reynolds numbers were tested in the experiments and the simulations, corresponding to a freestream velocity range of 60 m/s - 20 m/s and four vertical confinement levels were analyzed in the experiments. Six turbulence models were examined: k-omega SST, two versions of Spalart-Allmaras (SA and SARC) and three versions of k-epsilon. The geometry was determined to be a challenge to RANS models, which was demonstrated by the pressure coefficient data because the simulations predicted an opposite Reynolds number trend to the experiments in the separated region. Furthermore, the simulations were not able to predict distinctive pressure coefficient profiles seen in the experimental results, such as an inflection point along the streamwise centerline in the separated region and a double-peak in the spanwise direction across the top of the bump. However, the simulations did predict that the flowfield is insensitive to Reynolds number at and above ReL = 2.46 x 106, which is in agreement with the Reynolds number insensitivity determined experimentally. Increasing confinement increased the magnitude of the pressure coefficients over the bump, and the pressure at the peak of the bump went from about -1.2 in the least confined case to about -1.5 in the most confined case. However, there was no change in the shape of the profile. The examination of the various RANS turbulence models concluded that, for this curved geometry, the turbulence models with the curvature correction, k-omega SST and SARC, corresponded more closely to the experimental flow than those without a curvature correction. None of the k-epsilon models predicted separation, but SARC, SA and k-omega SST all did. It was determined that SARC, SA and k-omega SST all displayed similar flow features to those observed in the experimental flow visualizations, such as the general shape of the separated region and counter-rotating surface vortices that were symmetric across the streamwise centerline. However, the extent, location and width of the separated region varied. Along with variation in the size of the separation bubble predicted by each turbulence model, they also all predicted different values and profiles for pressure and skin friction coefficient in the separated region. From this experimental and computational analysis, it is clear that this geometry poses a sufficient challenge to current RANS models, due to their inability to accurately predict the location, size and values of pressure coefficients within the separated region. Therefore, is a good choice for a turbulent separated flow validation test. Future work on this project will focus on detailed flowfield comparisons between experiments and simulations.

Download or read book Turbulence Modelling Approaches written by Konstantin Volkov and published by BoD – Books on Demand. This book was released on 2017-07-26 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Accurate prediction of turbulent flows remains a challenging task despite considerable work in this area and the acceptance of CFD as a design tool. The quality of the CFD calculations of the flows in engineering applications strongly depends on the proper prediction of turbulence phenomena. Investigations of flow instability, heat transfer, skin friction, secondary flows, flow separation, and reattachment effects demand a reliable modelling and simulation of the turbulence, reliable methods, accurate programming, and robust working practices. The current scientific status of simulation of turbulent flows as well as some advances in computational techniques and practical applications of turbulence research is reviewed and considered in the book.

Download or read book Turbulent Flows written by Jean Piquet and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 767 pages. Available in PDF, EPUB and Kindle. Book excerpt: obtained are still severely limited to low Reynolds numbers (about only one decade better than direct numerical simulations), and the interpretation of such calculations for complex, curved geometries is still unclear. It is evident that a lot of work (and a very significant increase in available computing power) is required before such methods can be adopted in daily's engineering practice. I hope to l"Cport on all these topics in a near future. The book is divided into six chapters, each· chapter in subchapters, sections and subsections. The first part is introduced by Chapter 1 which summarizes the equations of fluid mechanies, it is developed in C~apters 2 to 4 devoted to the construction of turbulence models. What has been called "engineering methods" is considered in Chapter 2 where the Reynolds averaged equations al"C established and the closure problem studied (§1-3). A first detailed study of homogeneous turbulent flows follows (§4). It includes a review of available experimental data and their modeling. The eddy viscosity concept is analyzed in §5 with the l"Csulting ~alar-transport equation models such as the famous K-e model. Reynolds stl"Css models (Chapter 4) require a preliminary consideration of two-point turbulence concepts which are developed in Chapter 3 devoted to homogeneous turbulence. We review the two-point moments of velocity fields and their spectral transforms (§ 1), their general dynamics (§2) with the particular case of homogeneous, isotropie turbulence (§3) whel"C the so-called Kolmogorov's assumptions are discussed at length.

Download or read book The Aerodynamics of Heavy Vehicles Trucks Buses and Trains written by Rose McCallen and published by Springer Science & Business Media. This book was released on 2004-09 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book includes the carefully edited contributions to the United Engineering Foundation Conference: The Aerodynamics of Heavy Vehicles: Trucks, Buses and Trains held in Monterey, California from December 2-6, 2002. This conference brought together 90 leading engineering researchers discussing the aerodynamic drag of heavy vehicles. The book topics include a comparison of computational fluid dynamics calculations using both steady and unsteady Reynolds-averaged Navier-Stokes, large-eddy simulation, and hybrid turbulence models and experimental data obtained from wind tunnel experiments. Advanced experimental techniques including three-dimensional particle image velocimetry are presented as well, along with their use in evaluating drag reduction devices.

Download or read book Progress in the Development and Validation of Turbulence Models for the Computation of 3 D Supersonic Flows with Crossflow Separation written by H. Deniau and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Engineering Turbulence Modelling and Experiments 5 written by W. Rodi and published by Elsevier. This book was released on 2002-08-21 with total page 1029 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulence is one of the key issues in tackling engineering flow problems. As powerful computers and accurate numerical methods are now available for solving the flow equations, and since engineering applications nearly always involve turbulence effects, the reliability of CFD analysis depends increasingly on the performance of the turbulence models. This series of symposia provides a forum for presenting and discussing new developments in the area of turbulence modelling and measurements, with particular emphasis on engineering-related problems. The papers in this set of proceedings were presented at the 5th International Symposium on Engineering Turbulence Modelling and Measurements in September 2002. They look at a variety of areas, including: Turbulence modelling; Direct and large-eddy simulations; Applications of turbulence models; Experimental studies; Transition; Turbulence control; Aerodynamic flow; Aero-acoustics; Turbomachinery flows; Heat transfer; Combustion systems; Two-phase flows. These papers are preceded by a section containing 6 invited papers covering various aspects of turbulence modelling and simulation as well as their practical application, combustion modelling and particle-image velocimetry.

Download or read book Engineering Turbulence Modelling and Experiments 6 written by Wolfgang Rodi and published by Elsevier. This book was released on 2005-05-05 with total page 1011 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the world renowned ERCOFTAC (International Symposium on Engineering Turbulence Modelling and Measurements). The proceedings include papers dealing with the following areas of turbulence: · Eddy-viscosity and second-order RANS models · Direct and large-eddy simulations and deductions for conventional modelling · Measurement and visualization techniques, experimental studies · Turbulence control · Transition and effects of curvature, rotation and buoyancy on turbulence · Aero-acoustics · Heat and mass transfer and chemically reacting flows · Compressible flows, shock phenomena · Two-phase flows · Applications in aerospace engineering, turbomachinery and reciprocating engines, industrial aerodynamics and wind engineering, and selected chemical engineering problems Turbulence remains one of the key issues in tackling engineering flow problems. These problems are solved more and more by CFD analysis, the reliability of which depends strongly on the performance of the turbulence models employed. Successful simulation of turbulence requires the understanding of the complex physical phenomena involved and suitable models for describing the turbulent momentum, heat and mass transfer. For the understanding of turbulence phenomena, experiments are indispensable, but they are equally important for providing data for the development and testing of turbulence models and hence for CFD software validation. As in other fields of Science, in the rapidly developing discipline of turbulence, swift progress can be achieved only by keeping up to date with recent advances all over the world and by exchanging ideas with colleagues active in related fields.

Download or read book Turbulence Modeling for CFD CD ROM written by David C. Wilcox and published by . This book was released on 2006 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Simple Two equation Turbulence Model for Transition sensitive CFD Simulations of Missile Nose cone Geometries written by Joseph Matthew Jones and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study reports the development and validation of a modified two-equation eddy-viscosity turbulence model for computational fluid dynamics prediction of transitional and turbulent flows. The existing terms of the standard k-w model have been modified to include transitional flow effects, within the framework of Reynolds-averaged, eddy-viscosity turbulence modeling. The new model has been implemented into the commercially available flow solver FLUENT and the Mississippi State University SimCenter developed flow solver U2NCLE. Test cases included flow over a flat plate, a 2-D circular cylinder in a crossflow, a 3-D cylindrical body and three conical geometries, which represent the nose-cones of aerodynamic vehicles such as missiles. The results illustrate the ability of the model to yield reasonable predictions of transitional flow behavior using a simple modeling framework, including an appropriate response to freestream turbulence quantities, boundary-layer separation, and angle of attack.

Download or read book Engineering Turbulence Modelling and Experiments 3 written by G. Bergeles and published by Newnes. This book was released on 2012-12-02 with total page 932 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents and discussses new developments in the area of turbulence modelling and measurements, with particular emphasis on engineering-related problems. At present, turbulence is one of the key issues in tackling engineering flow problems. Powerful computers and numerical methods are now available for solving the flow equations, but the simulation of turbulence effects which are nearly always important in practice, is still in an unsatisfactory state and introduces considerable uncertainities in the accuracy of CFD calculations. These and other aspects of turbulence modelling and measurements are dealt with in detail by experts in the field. The resulting book is an up-to-date review of the most recent research in this exciting area.

Download or read book Implementation and Validation of a Modified Non equilibrium Wilcox K Omega Turbulence Model in Subsonic and Transonic Flow Regimes written by Thomas L. Kudla and published by . This book was released on 2013 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large Eddy Simulations (LES) are beginning to emerge as the state-of-the art for turbulence modeling in Computational Fluid Dynamics (CFD), but due to current computational constraints, the need will continue to exist for a lower fidelity, yet robust set of Reynolds-Averaged Navier- Stokes (RANS) turbulence models. Many of these turbulence models are based off of the classic Boussinesq approximation which relates the mean flow stresses to the turbulent eddy viscosity. The traditional Boussinesq approximation relies upon the instantaneous strain rate which may produce large errors in solutions for flows with significant changes in strain (such as areas of massive separation and re-attachment). The unstructured Navier-Stokes solver AVUS is modified using a new method developed by Peter E. Hamlington and Werner J. A. Dahm which replaces the classic Boussinesq approximation with a new non-equilibrium closure technique. The new non-equilibrium k omega turbulence model modification takes into account the time history of the strain rate by modifying the eddy viscosity term found in the k omega Wilcox turbulence model. Computational results from this new model are compared to experimental data from numerous test cases which include a two-dimensional flat plate, NACA 0012 airfoil, RAE 2822 transonic airfoil, and a fully three-dimensional unmanned aerial vehicle. The results of the new model are encouraging since they are more closely correlating to experimental data.

Download or read book CFL3D User s Manual Version 5 0 written by Sherrie L. Krist and published by . This book was released on 1998 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: