Download or read book The Sensitivity Analysis in K epsilon Turbulence Modeling Applied to Jet Flows written by Farhad Raiszadeh and published by . This book was released on 1984 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analysis of the K epsilon Turbulence Models for Simulation of Compressible Flows written by Krishnendu Sinha and published by . This book was released on 2001 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Turbulent Jets written by N. Rajaratnam and published by Elsevier. This book was released on 1976-01-01 with total page 315 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent Jets

Download or read book Near wall K epsilon Turbulence Modeling written by and published by . This book was released on 1987 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Computation of Turbulent Flows Using an Extended K Epsilon Turbulence Closure Model written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-26 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: An extended kappa-epsilon turbulence model is proposed and tested with successful results. An improved transport equation for the rate of dissipation of the turbulent kinetic energy, epsilon, is proposed. The proposed model gives more effective response to the energy production rate than does the standard kappa-epsilon turbulence model. An extra time scale of the production range is included in the dissipation rate equation. This enables the present model to perform equally well for several turbulent flows with different characteristics, e.g., plane and axisymmetric jets, turbulent boundary layer flow, turbulent flow over a backward-facing step, and a confined turbulent swirling flow. A second-order accurate finite difference boundary layer code and a nearly second-order accurate finite difference elliptic flow solver are used for the present numerical computations. Chen, Y.-S. and Kim, S.-W. Unspecified Center NASA-CR-179204, NAS 1.26:179204 NAS8-35918

Download or read book Uncertainty Quantification of Turbulence Model Closure Coefficients in OpenFOAM and Fluent for Mildly Separated Flows written by Isaac Russell Witte and published by . This book was released on 2017 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, detailed uncertainty quantification studies focusing on the closure coefficients of eddy-viscosity turbulence models for several flows using two CFD solvers have been performed. Three eddy viscosity turbulence models considered are: the one-equation Spalart-Allmaras (SA) model, the two-equation Shear Stress Transport (SST) k-[omega] model, and the one-equation Wray-Agarwal (WA) model. OpenFOAM and ANSYS Fluent are used as flow solvers. Uncertainty quantification analyses are performed for subsonic flow over a flat plate, subsonic flow over a backward-facing step, and transonic flow past an axisymmetric bump. In the case of flat plate, coefficients of pressure, lift, drag, and skin friction are considered to be the output quantities of interest. In case of the backward-facing step, these quantities are considered along with the separation bubble size. In case of an axisymmetric transonic bump, the drag coefficient, lift coefficient, separation point and reattachment point are considered. In addition to these four quantities, global uncertainty is employed on every node in the flow for Reynolds shear stress to determine which areas of the flow the closure coefficients contribute most to the uncertainty. Uncertainty quantification is conducted using DAKOTA developed by Sandia National Laboratories using stochastic expansions based on non-intrusive polynomial chaos. All closure xii coefficients are treated as epistemic uncertain variables, each defined by a specified range. The influence of the closure coefficients on output quantities is assessed using the global sensitivity analysis based on variance decomposition. This yields Sobol indices which are used to rank the contributions of each constant. A comparison of the Sobol indices between the turbulence models, flow cases, and flow solvers is conducted. This research identifies closure coefficients for each turbulence model that contribute significantly to uncertainty in the model predictions; this information can then be used to improve the prediction capability of the models in separated flow region by a more judicious choice of the closure coefficients.

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 An Improved K Epsilon Model for Near Wall Turbulence and Comparison with Direct Numerical Simulation written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-16 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: An improved k-epsilon model for low Reynolds number turbulence near a wall is presented. The near-wall asymptotic behavior of the eddy viscosity and the pressure transport term in the turbulent kinetic energy equation is analyzed. Based on this analysis, a modified eddy viscosity model, having correct near-wall behavior, is suggested, and a model for the pressure transport term in the k-equation is proposed. In addition, a modeled dissipation rate equation is reformulated. Fully developed channel flows were used for model testing. The calculations using various k-epsilon models are compared with direct numerical simulations. The results show that the present k-epsilon model performs well in predicting the behavior of near-wall turbulence. Significant improvement over previous k-epsilon models is obtained. Shih, T. H. Glenn Research Center NASA-TM-103221, ICOMP-90-16, E-5635, NAS 1.15:103221 NASA ORDER C-99066-G; RTOP 505-62-21...

Download or read book Energy Research Abstracts written by and published by . This book was released on 1984 with total page 1430 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1991 with total page 938 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 NASA Technical Memorandum written by and published by . This book was released on 1994 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Improved K epsilon Model for Near wall Turbulence and Comparison with Direct Numerical Simulation written by and published by . This book was released on 1990 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Powertrain Systems for a Sustainable Future written by Institution of Mechanical Engineers (IMechE) and published by CRC Press. This book was released on 2023-11-02 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: The transport sector continues to shift towards alternative powertrains, particularly with the UK Government’s focus on ending the sale of petrol and diesel passenger cars by 2030 and increasing support for alternatives. Despite this announcement, the internal combustion could continue to play a significant role both in the passenger car market through the use of hybrids and sustainable low carbon fuels including hydrogen, as well as a key role in other sectors such as heavy-duty vehicles and off-highway applications across the globe. The contributions presented at the International Conference on Powertrain Systems for a Sustainable Future 2023 (London, UK, 29- 30 November 2023) focus on the internal combustion engine’s role in net-zero transport as well as covering developments in the wide range of propulsion systems available (electric, hydrogen internal combustion engines and fuel cells, sustainable fuels etc) and their associated powertrains. To achieve a sustainable future for transport across the globe we will need to deploy all technologies and so, to help understand how these might fit together, life-cycle analysis of future powertrain systems and energy will also be included. Powertrain Systems for a Sustainable Future provides a forum for engine, fuels, e-machine, fuel cell and powertrain experts to look closely at developments in powertrain technology required to meet the demands of the net-zero future and global competition in all sectors of the road transportation, off-highway, marine and stationary power industries.

Download or read book A New Time Scale Based K Epsilon Model for Near Wall Turbulence written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-28 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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...