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Dns Of Hypersonic Boundary Layer Stability And Transition Using High Order Nonuniform Grid Schemes
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Book Synopsis DNS of Hypersonic Boundary Layer Stability and Transition Using High-Order Nonuniform-Grid Schemes by : Xiaolin Zhong
Download or read book DNS of Hypersonic Boundary Layer Stability and Transition Using High-Order Nonuniform-Grid Schemes written by Xiaolin Zhong and published by . This book was released on 2001 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-order schemes are necessary for the DNS of stability and transition of hypersonic boundary layers because lower-order schemes do not have a sufficient accuracy level to compute small flow details. Currently, the main limiting factor in the application of high-order schemes is the numerical instability of high-order boundary closure schemes. In a previous AIAA paper (2001-0437), we presented a family of high-order nonuniform-grid finite-difference schemes with stable boundary closures for multi-dimensional flow simulations. In this paper, the high-order nominiform-grid schemes (up to 11th order) are applied to the numerical simulation of the receptivity of hypersonic boundary layers to freestream disturbances over a blunt leading edge. The stability and numerical accuracy of the new high-order nonuniform-grid schemes are evaluated for computing the nonlinear 2-D Navier-Stokes equations for hypersonic flow simulations.
Book Synopsis DNS Studies of Transitional Hypersonic Reacting Flows Over 3-D Hypersonic Vehicles by : Xiaolin Zhong
Download or read book DNS Studies of Transitional Hypersonic Reacting Flows Over 3-D Hypersonic Vehicles written by Xiaolin Zhong and published by . This book was released on 2003 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Direct Numerical Simulation and Experimental Validation of Hypersonic Boundary-layer Receptivity and Instability by : Xiaolin Zhong
Download or read book Direct Numerical Simulation and Experimental Validation of Hypersonic Boundary-layer Receptivity and Instability written by Xiaolin Zhong and published by . This book was released on 2007 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research project is to compare our numerical simulation solutions with available experimental or theoretical results on hypersonic boundary layer receptivity and stability; and to conduct extensive DNS studies on the flow mechanisms of hypersonic boundary layer receptivity and stability. During the three-year period, we have conducted extensive DNS studies on the receptivity of hypersonic boundary layer flows over a sharp wedge, a flat plate, a blunt cone, and the FRESH aeroshell. DNS studies are compared with Stetson's 1984 stability experiment on Mach 7.99 flow over a blunt cone, and Maslov's leading-edge receptivity experiment on Mach 5.92 flow over a flat plate. Our numerical studies have been validated to be of high accuracy and led to further understanding of hypersonic boundary layer receptivity mechanism. Such understanding can lead to better tools for the prediction and control of high-speed boundary layer transition.
Book Synopsis Direct Numerical Simulation and Linear Analysis of Stability of Nonequilibrium Hypersonic Boundary Layers by : Xiaolin Zhong
Download or read book Direct Numerical Simulation and Linear Analysis of Stability of Nonequilibrium Hypersonic Boundary Layers written by Xiaolin Zhong and published by . This book was released on 1998 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this research project is to develop new advanced numerical methods and to perform direct numerical simulation (DNS) studies of transient hypersonic reacting flows over full 3-D maneuvering vehicles. The DNS tools and supporting theoretical approaches are used to gain new fundamental understanding of transition phenomena of 3-D chemically-reacting hypersonic boundary layers. Our research accomplishments in the report period can be classified into three areas. First, we have developed and validated new efficient and high-order accurate numerical methods for the DNS of 3-D hypersonic reacting boundary layers. The new methods include high-order semi-implicit Runge-Kutta schemes and new upwind high-order finite-difference shock-fitting schemes. These new methods were developed in order to overcome the difficulties associated with the DNS of hypersonic reacting flows with shock waves. Second, we have conducted extensive studies on the stability and receptivity phenomena of hypersonic boundary layers over blunt leading edges and elliptical cross-section blunt cones both by direct numerical simulation and by linear stability analyses. Third, the effects of using Burnett equations for rarefied hypersonic flow computations were investigated.
Book Synopsis High Order Semi-implicit Simulation of Hypersonic Boundary Layer Stability and Transition by : Haibo Dong
Download or read book High Order Semi-implicit Simulation of Hypersonic Boundary Layer Stability and Transition written by Haibo Dong and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Effective Fourth Order Finite Volume Method for DNS/LES on Non-Uniform Grid by : F. Iannelli
Download or read book An Effective Fourth Order Finite Volume Method for DNS/LES on Non-Uniform Grid written by F. Iannelli and published by . This book was released on 2001 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper is concerned with the development of a fourth order Finite Volume scheme for the numerical solution of the incompressible Navier-Stokes equations on non-uniform grids. In fact, the use of non-uniform computational grids is inevitable in handling non-homogeneous flow computations, while numerical simulation of turbulent flows demand for higher order schemes. The effective high order accuracy is obtained by reformulating the momentum equation in terms of a fourth order deconvolved velocity field. Both a proper integration and flux reconstruction is implemented for the space discretization. A Fractional Time-Step method for the pressure-velocity de-coupling is adopted and a second order semi-implicit scheme is used for the time integration. Particular attention has been devoted in developing congruent time-accurate intermediate boundary conditions for the predictor step.
Book Synopsis Numerical Simulation of Hypersonic Boundary Layer Receptivity, Transient Growth and Transition With Surface Roughness by :
Download or read book Numerical Simulation of Hypersonic Boundary Layer Receptivity, Transient Growth and Transition With Surface Roughness written by and published by . This book was released on 2009 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research is to conduct DNS studies of hypersonic boundary layer receptivity, transient growth and transition with surface roughness. The main approach is to use DNS as a research tool to study the boundary layer receptivity and transient-growth mechanisms in hypersonic flows, including the development of numerical algorithms and parallel computer codes of higher order numerical methods for the simulation of hypersonic flows with surface roughness of finite heights. During the three-year period, we have conducted DNS studies on the hypersonic boundary layer flows over flat plates and blunt cones. A new high-order cut-cell method has been developed for the numerical simulation of hypersonic boundary layer transition with finite height surface roughness. The method has been applied to the numerical simulations of two-dimensional hypersonic flows over a flat plate. Furthermore, the stabilization effect of the surface porous coating over a flat plate is extensively studied by series of numerical simulations. We also collaborate with Prof. Tumin in the University of Arizona to compare numerical and theoretical results on receptivity of a Mach 5.92 flow over a flat plate to wall blowing-suction, and to analyze the nonparallel flow effect.
Book Synopsis Numerical Studies of Low-Density Two-Dimensional Hypersonic Flows by Using the Navier-Stokes and Burnett Equations with Nonequilibrium Real Gas Effects by :
Download or read book Numerical Studies of Low-Density Two-Dimensional Hypersonic Flows by Using the Navier-Stokes and Burnett Equations with Nonequilibrium Real Gas Effects written by and published by . This book was released on 1997 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this research is to study the laminar turbulent transition and other transient flow phenomena of 3-D chemically reacting hypersonic boundary layers by direct numerical simulation (DNS) and by linear stability analysis. The research in the report period was focused on developing new numerical methods for such studies and studying several fundamental transient hypersonic flow phenomena. First, several new efficient and high-order accurate numerical methods for DNS of 3-D hypersonic reacting boundary layers and for computing unsteady hypersonic flows with complex shock interactions were developed. These new methods were developed in order to overcome difficulties associated with the direct numerical simulation of hypersonic flows. Second, several studies on the stability phenomena of hypersonic boundary layers over blunt leading edges both by direct numerical simulation and by linear stability analyses were performed. Also completed were extensive numerical studies on real gas effects on a steady shock/boundary layer interaction and a self-sustained unsteady shock-shock interference heating flows. Third, the effects of using Burnett equations for rarefied hypersonic flow computations were investigated. With the completion of the bulk of work on the development of new numerical methods for complex hypersonic flow simulation, the DNS studies are currently being extended to 3-D hypersonic boundary layer transition over elliptic cross section cones.
Book Synopsis DNS of Boundary Layer Transition Induced by a Coherent Perturbation by : H. C. de Lange
Download or read book DNS of Boundary Layer Transition Induced by a Coherent Perturbation written by H. C. de Lange and published by . This book was released on 2001 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bypass transition of a boundary layer takes place at high main stream turbulence levels. It is governed by the intrusion of non-linear disturbances into the viscous sublayer. In this paper a numerical study is presented in which a spatially developing laminar boundary layer is subdued to large scale (non- linear) disturbances. The (fully compressible) Navier-Stokes equations are solved using direct numerical simulation with a higher order finite difference method on a collocated grid. The results show that the initially smooth disturbance rapidly changes into an arrow-head structure with the characteristics of a turbulent spot.
Book Synopsis Linear and Nonlinear Processes in Hypersonic Boundary Layer Transition to Turbulence by : Kenneth Joseph Franko
Download or read book Linear and Nonlinear Processes in Hypersonic Boundary Layer Transition to Turbulence written by Kenneth Joseph Franko and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The design of vehicles which travel at hypersonic speeds is strongly determined by drag characteristics and heat transfer. A portion of this drag and heating is due to the boundary layer where viscosity and thermal conductivity are most important. The level of drag and heating depends on whether the boundary layer is laminar or turbulent with the latter leading to higher levels of drag and heating. In addition, as high speed boundary layers transition from laminar to turbulent flow, an overshoot of the heat transfer beyond that of turbulent flow has been observed in experiments. In low disturbance environments, transition to turbulence follows the path of receptivity, linear growth, nonlinear interaction, and finally breakdown to turbulence. The linear growth of disturbances can be determined by linear stability theory. An analysis of the predicted growth rates and integrated growth of linear disturbances for hypersonic boundary layers including thermal and chemical non-equilibrium is undertaken. The sensitivity to different chemical assumptions, transport models and thermal boundary conditions is investigated. A disturbance energy norm is proposed and its corresponding balance equation is derived. This energy norm is then to determine the effect of different terms of the linear stability equations and to compute transient growth for hypersonic laminar boundary layers. DNS (Direct Numerical Simulation) is used to simulate the nonlinear breakdown to turbulence for a variety of transition scenarios for both zero pressure gradient and adverse pressure gradient high-speed flat plate boundary layers in order to investigate the mechanism for the overshoot of heat transfer in transitional hypersonic boundary layers. The initial disturbances are excited through suction and blowing at the wall and their frequencies are chosen based on linear stability theory. Different transition mechanisms are investigated including a pair of oblique waves and 2D and 3D instabilities at higher frequencies which are unique to high speed boundary layers. Oblique breakdown shows a clear overshoot in heat transfer and skin friction and leads to a fully turbulent boundary layer. The alternative scenarios also lead to transition but further downstream and without large overshoots in heat transfer. A detailed analysis of the transitional and turbulent regions is undertaken.
Book Synopsis Effects of Thermochemical Nonequilibrium on Hypersonic Boundary-Layer Instability in the Presence of Surface Ablation Or Isolated Two-Dimensional Roughness by : Clifton Mortensen
Download or read book Effects of Thermochemical Nonequilibrium on Hypersonic Boundary-Layer Instability in the Presence of Surface Ablation Or Isolated Two-Dimensional Roughness written by Clifton Mortensen and published by . This book was released on 2015 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt: The current understanding of the effects of thermochemical nonequilibrium on hypersonic boundary-layer instability still contains uncertainties, and there has been little research into the effects of surface ablation, or two-dimensional roughness, on hypersonic boundary-layer instability. The objective of this work is to study the effects of thermochemical nonequilibrium on hypersonic boundary-layer instability. More specifically, two separate nonequilibrium flow configurations are studied: 1) flows with graphite surface ablation, and 2) flows with isolated two-dimensional surface roughness. These two flow types are studied numerically and theoretically, using direct numerical simulation and linear stability theory, respectively. To study surface ablation, a new high-order shock-fitting method with thermochemical nonequilibrium and finite-rate chemistry boundary conditions for graphite ablation is developed and validated. The method is suitable for direct numerical simulation of boundary-layer transition in a hypersonic real-gas flow with graphite ablation. The new method is validated by comparison with three computational data sets and one set of experimental data. Also, a thermochemical nonequilibrium linear stability theory solver with a gas phase model that includes multiple carbon species, as well as a linearized surface graphite ablation model, is developed and validated. It is validated with previously published linear stability analysis and direct numerical simulation results. A high-order method for discretizing the linear stability equations is used which can easily include high-order boundary conditions. The developed codes are then used to study hypersonic boundary-layer instability for a 7 deg half angle blunt cone at Mach 15.99 and the Reentry F experiment at 100~kft. Multiple simulations are run with the same geometry and freestream conditions to help separate real gas, blowing, and carbon species effects on hypersonic boundary-layer instability. For the case at Mach 15.99, a directly simulated 525~kHz second-mode wave was found to be significantly unstable for the real-gas simulation, while in the ideal-gas simulations, no significant flow instability is seen. An N factor comparison also shows that real-gas effects significantly destabilize the flow when compared to an ideal gas. Blowing is destabilizing for the real gas simulation and has a negligible effect for the ideal gas simulation due to the different locations of instability onset. Notably, carbon species resulting from ablation are shown to slightly stabilize the flow for both cases. For the Reentry F flow conditions, inclusion of the ablating nose cone was shown to increase the region of second mode growth near the nose cone. Away from the nose cone, the second mode was relatively unaffected. Experimental and numerical results have shown that two-dimensional surface roughness can stabilize a hypersonic boundary layer dominated by second-mode instability. It is sought to understand how this physical phenomenon extends from an airflow under a perfect gas assumption to that of a flow in thermochemical nonequilibrium. To these ends, a new high-order shock-fitting method that includes thermochemical nonequilibrium and a cut-cell method, to handle complex geometries unsuitable for structured body-fitted grids, is presented. The new method is designed specifically for direct numerical simulation of hypersonic boundary-layer transition in a hypersonic real-gas flow with arbitrary shaped surface roughness. The new method is validated and shown to perform comparably to a high-order method with a body-fitted grid. For a Mach 10 flow over a flat plate, a two-dimensional roughness element was found to stabilize the second mode when placed downstream of the synchronization location. This result is consistent with previous results for perfect-gas flows. For a Mach 15 flow over a flat plate, a two-dimensional surface roughness element stabilizes the second-mode instability more effectively in a thermochemical nonequilibrium flow, than in a corresponding perfect gas flow.
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 974 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Book Synopsis Large-Eddy Simulations of Turbulence by : M. Lesieur
Download or read book Large-Eddy Simulations of Turbulence written by M. Lesieur and published by Cambridge University Press. This book was released on 2005-08-22 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large-Eddy Simulations of Turbulence is a reference for LES, direct numerical simulation and Reynolds-averaged Navier-Stokes simulation.
Book Synopsis Nodal Discontinuous Galerkin Methods by : Jan S. Hesthaven
Download or read book Nodal Discontinuous Galerkin Methods written by Jan S. Hesthaven and published by Springer Science & Business Media. This book was released on 2007-12-18 with total page 507 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers an introduction to the key ideas, basic analysis, and efficient implementation of discontinuous Galerkin finite element methods (DG-FEM) for the solution of partial differential equations. It covers all key theoretical results, including an overview of relevant results from approximation theory, convergence theory for numerical PDE’s, and orthogonal polynomials. Through embedded Matlab codes, coverage discusses and implements the algorithms for a number of classic systems of PDE’s: Maxwell’s equations, Euler equations, incompressible Navier-Stokes equations, and Poisson- and Helmholtz equations.
Book Synopsis Boundary Layer Flows by : Vallampati Ramachandra Prasad
Download or read book Boundary Layer Flows written by Vallampati Ramachandra Prasad and published by BoD – Books on Demand. This book was released on 2020-01-22 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by experts in the field, this book, "Boundary Layer Flows - Theory, Applications, and Numerical Methods" provides readers with the opportunity to explore its theoretical and experimental studies and their importance to the nonlinear theory of boundary layer flows, the theory of heat and mass transfer, and the dynamics of fluid. With the theory's importance for a wide variety of applications, applied mathematicians, scientists, and engineers - especially those in fluid dynamics - along with engineers of aeronautics, will undoubtedly welcome this authoritative, up-to-date book.
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.
