Quantification of Spalart-Allmaras Turbulence Modeling Uncertainties for Hypersonic Flows Utilizing Output-based Grid Adaptation

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Book Synopsis Quantification of Spalart-Allmaras Turbulence Modeling Uncertainties for Hypersonic Flows Utilizing Output-based Grid Adaptation by : Carter John Waligura

Download or read book Quantification of Spalart-Allmaras Turbulence Modeling Uncertainties for Hypersonic Flows Utilizing Output-based Grid Adaptation written by Carter John Waligura and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, uncertainty in the Spalart-Allmaras (SA) turbulence model with the compressible Reynolds-averaged Navier-Stokes (RANS) equations is quantified for steady non-reacting hypersonic flows using a coarse-grained uncertainty metric. Output-based adaptation is utilized to guarantee negligible numerical error with complex flow features, such as shock wave-boundary-layer interactions (SBLI). The adapted meshes are generated using MIT Solution Adaptive Numerical Simulator (SANS) software, which is able to adapt high order unstructured meshes using a modified Continuous Galerkin (CG) finite element method (FEM) discretization. The meshes are iteratively adapted by minimizing the error estimate of a given output functional, such as integrated drag or heat flux, over a boundary. The goal of the study is to quantify the expected uncertainty bounds when using the SA model with modifications to the key assumptions of a linear eddy viscosity constitutive relation and incompressible flow. The uncertainty comparison is made between specific areas of hypersonic geometries such as the pre-compression flat plate region and the post-compression shocked-wedge region of a compression corner. Ultimately, this study improves the determination of uncertainty bounds in engineering design involving turbulent flow, provides more insight into exemplary meshing practices for high-speed flow involving SBLI, and highlights where additional work is needed for the development of turbulence models in the hypersonic regime.

Uncertainty Quantification of Turbulence Model Closure Coefficients for Transonic Wall-bounded Flows

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ISBN 13 :
Total Pages : 92 pages
Book Rating : 4.:/5 (936 download)

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Book Synopsis Uncertainty Quantification of Turbulence Model Closure Coefficients for Transonic Wall-bounded Flows by : John Anthony Schaefer

Download or read book Uncertainty Quantification of Turbulence Model Closure Coefficients for Transonic Wall-bounded Flows written by John Anthony Schaefer and published by . This book was released on 2015 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The goal of this work was to quantify the uncertainty and sensitivity of commonly used turbulence models in Reynolds-Averaged Navier-Stokes codes due to uncertainty in the values of closure coefficients for transonic, wall-bounded flows and to rank the contribution of each coefficient to uncertainty in various output flow quantities of interest. Specifically, uncertainty quantification of turbulence model closure coefficients was performed for transonic flow over an axisymmetric bump at zero degrees angle of attack and the RAE 2822 transonic airfoil at a lift coefficient of 0.744. Three turbulence models were considered: the Spalart-Allmaras Model, Wilcox (2006) [kappa]-[omega] Model, and the Menter Shear-Stress Transport Model. The FUN3D code developed by NASA Langley Research Center and the BCFD code developed by The Boeing Company were used as the flow solvers. The uncertainty quantification analysis employed stochastic expansions based on non-intrusive polynomial chaos as an efficient means of uncertainty propagation. Several integrated and point-quantities are considered as uncertain outputs for both CFD problems. All closure coefficients were treated as epistemic uncertain variables represented with intervals. Sobol indices were used to rank the relative contributions of each closure coefficient to the total uncertainty in the output quantities of interest. Two studies were performed in this work. The main study identified a number of closure coefficients for each turbulence model for which more information will reduce the amount of uncertainty in the output significantly for transonic, wall-bounded flows. A case study demonstrated that the RAE 2822 sensitivity results of the main study are independent of the flow solver and of the computational grid topology and resolution"--Abstract, page iii.

Validation of the Spalart-Allmaras Turbulence Model for Application in Hypersonic Flows

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Book Synopsis Validation of the Spalart-Allmaras Turbulence Model for Application in Hypersonic Flows by : R. Paciorri

Download or read book Validation of the Spalart-Allmaras Turbulence Model for Application in Hypersonic Flows written by R. Paciorri and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Gradient-based Approaches for Sensitivity Analysis and Uncertainty Quantification Within Hypersonic Flows

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ISBN 13 : 9781267323378
Total Pages : 195 pages
Book Rating : 4.3/5 (233 download)

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Book Synopsis Gradient-based Approaches for Sensitivity Analysis and Uncertainty Quantification Within Hypersonic Flows by : Brian A. Lockwood

Download or read book Gradient-based Approaches for Sensitivity Analysis and Uncertainty Quantification Within Hypersonic Flows written by Brian A. Lockwood and published by . This book was released on 2012 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the proliferation of simulation within the design and analysis of engineering systems, uncertainty quantification and sensitivity analysis have taken on increased importance, providing valuable information for assessing the reliability of simulation outputs and a means for improving these results. In this work, uncertainty quantification and sensitivity analysis within the context of hypersonic computational fluid dynamics is examined. The simulation of hypersonic relies on numerous constitutive relations to account for chemical reactions, internal energy modes and molecular transport. Within these constitutive relations are hundreds of constants and parameters, which are often the result of experimental measurements. The goal of sensitivity analysis is determining the simulation parameters most affecting an output of interest, while the goal of uncertainty quantification is determining the variability of simulation outputs resulting from the uncertainty associated with model parameters. Traditional methods for uncertainty quantification and sensitivity analysis typically rely on exhaustive sampling, where hundreds to thousands of simulations are performed and relevant statistics are computed. For complex simulations, these exhaustive approaches are prohibitively expensive and well beyond the computational budget of most projects. For this work, gradient-based methods are used to reduce the expense of uncertainty quantification and sensitivity analysis. Using an adjoint-based approach, the derivative of an output with respect to simulation parameters can be computed in a constant amount of work, providing more information about the simulation output without a significant increase in cost. This additional information can then be leveraged in novel ways, such as surrogate models or optimization, to accelerate the process of uncertainty quantification or sensitivity analysis. This dissertation demonstrates these gradient-based methods for sensitivity analysis and uncertainty quantification in hypersonic flow simulations and assesses the performance of these methods in terms of cost and accuracy.

Implementation and Validation of the Spalart-Allmaras Turbulence Model for Application in Hypersonic Flows

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ISBN 13 :
Total Pages : 30 pages
Book Rating : 4.:/5 (245 download)

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Book Synopsis Implementation and Validation of the Spalart-Allmaras Turbulence Model for Application in Hypersonic Flows by : R. Paciorri

Download or read book Implementation and Validation of the Spalart-Allmaras Turbulence Model for Application in Hypersonic Flows written by R. Paciorri and published by . This book was released on 1996 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Effect of Turbulence Model Closure Coefficient Uncertainty on Scramjet Flow Field Analysis

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ISBN 13 :
Total Pages : 83 pages
Book Rating : 4.:/5 (119 download)

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Book Synopsis Effect of Turbulence Model Closure Coefficient Uncertainty on Scramjet Flow Field Analysis by : Martin Albert Di Stefano

Download or read book Effect of Turbulence Model Closure Coefficient Uncertainty on Scramjet Flow Field Analysis written by Martin Albert Di Stefano and published by . This book was released on 2020 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The numerical modeling of supersonic combustion ramjet (scramjet) engine flow paths plays an important role in the design of hypersonic air-breathing propulsion systems. Due to the complexity of the flow field physics and limited experimental data, numerical models possess uncertainties which should be addressed to improve the prediction accuracy of the simulations. In this study, the effect of turbulence model closure coefficient uncertainty on the Reynolds-averaged Navier-Stokes solution of a scramjet isolator and scramjet strut fuel injector flow field is investigated with an uncertainty quantification and sensitivity analysis study for commonly used turbulence models. Turbulence models considered in this work are Menter-BSL, Menter-SST, Spalart-Allmaras, and Wilcox-2006 k-[omega]. Simulations were carried out using NASA's VULCAN flow solver. Nonintrusive polynomial chaos theory was used for efficient propagation of uncertainty, and Sobol indices were utilized to quantify the global non-linear sensitivity of various solution metrics to the variation of each closure coefficient. The scramjet isolator study considered the shock location, skin friction coefficient, and integrated axial shear force as output metrics of interest. The output metrics of interest for the strut fuel injector study included the integrated quantities of mixing efficiency, circulation, total pressure recovery, and one-dimensional Mach number, as well as the pointwise vorticity and eddy viscosity distributions, and were evaluated at three crossflow planes. The results obtained were compared to available experimental data as well as to previous work focusing on relevant flow problems and other sources of solution uncertainty. Influential sets of closure coefficients were identified for each turbulence model, with the Kármán and diffusion constants being the most prominent. The results presented in this work are expected to assist future efforts aimed at reducing the uncertainty in the numerical design of scramjet engine components through the identification of closure coefficients and physical aspects of the flow that warrant further investigation"--Abstract, page iii.

Evaluation of Various Turbulence Models for Shock-wave Boundary Layer Interaction Flows

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ISBN 13 :
Total Pages : 53 pages
Book Rating : 4.:/5 (961 download)

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Book Synopsis Evaluation of Various Turbulence Models for Shock-wave Boundary Layer Interaction Flows by : Francis Kofi Acquaye

Download or read book Evaluation of Various Turbulence Models for Shock-wave Boundary Layer Interaction Flows written by Francis Kofi Acquaye and published by . This book was released on 2016 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: Despite the modeling capabilities of current computational fluid dynamics (CFD), there still exist problems and inconsistencies in simulating fluid flow in certain flow regimes. Most difficult are the high-speed transonic, supersonic and hypersonic wall-bounded turbulent flows with small or massive regions of separation. To address the problem of the lack of computational accuracy in turbulence modeling, NASA has established the Turbulence Modeling Resource (TMR) website and has issued the NASA 40% Challenge. The aim of this challenge is to identify and improve/develop turbulence and transition models as well as numerical techniques to achieve a 40% reduction in the predictive error in computation of benchmark test cases for turbulent flows. One of the phenomena of considerable interest in the 40% Challenge is the shock-wave boundary layer interaction (SWBLI) that occurs on aircraft surfaces at transonic and supersonic speeds and on space vehicles at hypersonic speeds. The correct modeling of shock-waves is complex enough, but the occurrence of SWBLI adds to the complexity by promoting flow separation, heat transfer, and pressure gradients on the surface. SWBLI may occur in both the external and internal flow path of air and space vehicles; therefore, it is important to accurately predict this phenomenon to improve the design of aircraft and space vehicles. The majority of CFD codes utilize the Reynolds Averaged Navier-Stokes (RANS) equations and employ various turbulence models. The most common among these turbulent models are the one-equation Spalart-Allmaras (SA) model and the two-equation Shear Stress Transport (SST) k-[omega] model. In recent years the CFD community has, in greater number, also started to adopt Large-Eddy Simulation (LES), Direct Numerical Simulation (DNS), and hybrid RANS-LES approaches for improving the accuracy of simulations. However currently, solving the RANS equations with eddy-viscosity turbulence models remains the most commonly used simulation technique in industrial applications. In this research, the one-equation Wray-Agarwal (WA), SA, and SST k-[omega] turbulence models are used to simulate supersonic flows in a 2D compression corner at angles of 8° and 16°, a partial axisymmetric flare of 20°, a full-body conical axisymmetric flare of 20°, and an impinging shock over a flat plate at 6°, 10°, and 14°. The ANSYS Fluent and OpenFOAM flow solvers are employed. Inflow boundary conditions and mesh sensitivity are examined to ensure the grid independence of computed solutions. For each of the three turbulence models, heat transfer, surface pressure, skin friction, and velocity profiles are compared with the available experimental data. It is found that the results from the WA model are in similar or better agreement with the experimental data compared to the SA and SST k-[omega] models for the majority of cases considered.

Quantification of Structural Uncertainties in RANS Turbulence Models

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ISBN 13 :
Total Pages : 70 pages
Book Rating : 4.:/5 (768 download)

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Book Synopsis Quantification of Structural Uncertainties in RANS Turbulence Models by : Eric Alexander Dow

Download or read book Quantification of Structural Uncertainties in RANS Turbulence Models written by Eric Alexander Dow and published by . This book was released on 2011 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents an approach for building a statistical model for the structural uncertainties in Reynolds averaged Navier-Stokes (RANS) turbulence models. This approach solves an inference problem by comparing the results of RANS calculations to direct numerical simulation. The adjoint method is used to efficiently solve an inverse problem to determine the RANS turbulent viscosity field that most accurately reproduces the mean flow field computed by direct numerical simulation. The discrepancy between the inferred turbulent viscosity and the turbulent viscosity predicted by RANS is modeled as a Gaussian random field. Finally, the uncertainty in the turbulent viscosity field is propagated to the quantities of interest. Results are first presented for turbulent flow through a straight channel. To model the uncertainty in more complex flows, the procedure is repeated for a collection of flows through randomly generated geometries.

Turbulence Modeling Validation, Testing, and Development

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Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781722849597
Total Pages : 100 pages
Book Rating : 4.8/5 (495 download)

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Book Synopsis Turbulence Modeling Validation, Testing, and Development by : National Aeronautics and Space Administration (NASA)

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...

International Aerospace Abstracts

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ISBN 13 :
Total Pages : 1016 pages
Book Rating : 4.F/5 ( download)

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Book Synopsis International Aerospace Abstracts by :

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1016 pages. Available in PDF, EPUB and Kindle. Book excerpt:

New Results in Numerical and Experimental Fluid Mechanics VI

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Publisher : Springer Science & Business Media
ISBN 13 : 3540744584
Total Pages : 973 pages
Book Rating : 4.5/5 (47 download)

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Book Synopsis New Results in Numerical and Experimental Fluid Mechanics VI by : Cameron Tropea

Download or read book New Results in Numerical and Experimental Fluid Mechanics VI written by Cameron Tropea and published by Springer Science & Business Media. This book was released on 2007-10-26 with total page 973 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume features the contributions to the 15th Symposium of the STAB (German Aerospace Aerodynamics Association). Papers provide a broad overview of ongoing work in Germany, including high aspect ratio wings, low aspect ratio wings, bluff bodies, laminar flow control and transition, active flow control, hypersonic flows, aeroelasticity, aeroacoustics, mathematical fundamentals, numerical simulations, physical fundamentals, and facilities.

Modelling Fluid Flow

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Publisher : Springer Science & Business Media
ISBN 13 : 3662087979
Total Pages : 424 pages
Book Rating : 4.6/5 (62 download)

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Book Synopsis Modelling Fluid Flow by : János Vad

Download or read book Modelling Fluid Flow written by János Vad and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modelling Fluid Flow presents invited lectures, workshop summaries and a selection of papers from a recent international conference CMFF '03 on fluid technology. The lectures follow the current evolution and the newest challenges of the computational methods and measuring techniques related to fluid flow. The workshop summaries reflect the recent trends, open questions and unsolved problems in the mutually inspiring fields of experimental and computational fluid mechanics. The papers cover a wide range of fluids engineering, including reactive flow, chemical and process engineering, environmental fluid dynamics, turbulence modelling, numerical methods, and fluid machinery.

Analysis of the K-Epsilon Turbulence Model

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ISBN 13 :
Total Pages : 222 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Analysis of the K-Epsilon Turbulence Model by : B. Mohammadi

Download or read book Analysis of the K-Epsilon Turbulence Model written by B. Mohammadi and published by . This book was released on 1994-09-06 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aimed at applied mathematicians interested in the numerical simulation of turbulent flows. Centered around the k-&epsis; model, it also deals with other models such as one equation models, subgrid scale models and Reynolds Stress models. Presents the k-&epsis; method for turbulence in a language familiar to applied mathematicians, but has none of the technicalities of turbulence theory.

Computational Fluid Dynamics

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Publisher : Elsevier
ISBN 13 : 0080529674
Total Pages : 491 pages
Book Rating : 4.0/5 (85 download)

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Book Synopsis Computational Fluid Dynamics by : Jiri Blazek

Download or read book Computational Fluid Dynamics written by Jiri Blazek and published by Elsevier. This book was released on 2005-12-20 with total page 491 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational Fluid Dynamics (CFD) is an important design tool in engineering and also a substantial research tool in various physical sciences as well as in biology. The objective of this book is to provide university students with a solid foundation for understanding the numerical methods employed in today’s CFD and to familiarise them with modern CFD codes by hands-on experience. It is also intended for engineers and scientists starting to work in the field of CFD or for those who apply CFD codes. Due to the detailed index, the text can serve as a reference handbook too. Each chapter includes an extensive bibliography, which provides an excellent basis for further studies.

Shock Wave-Boundary-Layer Interactions

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Publisher : Cambridge University Press
ISBN 13 : 1139498649
Total Pages : 481 pages
Book Rating : 4.1/5 (394 download)

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Book Synopsis Shock Wave-Boundary-Layer Interactions by : Holger Babinsky

Download or read book Shock Wave-Boundary-Layer Interactions written by Holger Babinsky and published by Cambridge University Press. This book was released on 2011-09-12 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shock wave-boundary-layer interaction (SBLI) is a fundamental phenomenon in gas dynamics that is observed in many practical situations, ranging from transonic aircraft wings to hypersonic vehicles and engines. SBLIs have the potential to pose serious problems in a flowfield; hence they often prove to be a critical - or even design limiting - issue for many aerospace applications. This is the first book devoted solely to a comprehensive, state-of-the-art explanation of this phenomenon. It includes a description of the basic fluid mechanics of SBLIs plus contributions from leading international experts who share their insight into their physics and the impact they have in practical flow situations. This book is for practitioners and graduate students in aerodynamics who wish to familiarize themselves with all aspects of SBLI flows. It is a valuable resource for specialists because it compiles experimental, computational and theoretical knowledge in one place.

The Finite Volume Method in Computational Fluid Dynamics

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Publisher : Springer
ISBN 13 : 3319168746
Total Pages : 799 pages
Book Rating : 4.3/5 (191 download)

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Book Synopsis The Finite Volume Method in Computational Fluid Dynamics by : F. Moukalled

Download or read book The Finite Volume Method in Computational Fluid Dynamics written by F. Moukalled and published by Springer. This book was released on 2015-08-13 with total page 799 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook explores both the theoretical foundation of the Finite Volume Method (FVM) and its applications in Computational Fluid Dynamics (CFD). Readers will discover a thorough explanation of the FVM numerics and algorithms used for the simulation of incompressible and compressible fluid flows, along with a detailed examination of the components needed for the development of a collocated unstructured pressure-based CFD solver. Two particular CFD codes are explored. The first is uFVM, a three-dimensional unstructured pressure-based finite volume academic CFD code, implemented within Matlab. The second is OpenFOAM®, an open source framework used in the development of a range of CFD programs for the simulation of industrial scale flow problems. With over 220 figures, numerous examples and more than one hundred exercise on FVM numerics, programming, and applications, this textbook is suitable for use in an introductory course on the FVM, in an advanced course on numerics, and as a reference for CFD programmers and researchers.

Turbulence Modeling for CFD: CD-ROM

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ISBN 13 : 9781928729082
Total Pages : 522 pages
Book Rating : 4.7/5 (29 download)

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Book Synopsis Turbulence Modeling for CFD: CD-ROM by : David C. Wilcox

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: