Download or read book Note Hyperviscosity for Shock Turbulence Interactions written by and published by . This book was released on 2004 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over half a century ago, von Neumann and Richtmyer [1] introduced the idea of adding artificial viscosity to the Euler equations in order to help stabilize shock calculations. Their ideas regarding artificial viscosity influenced Smagorinsky [2, 3] in his development of a subgrid-scale model designed to match the Kolmogorov spectrum for atmospheric turbulence (C.E. Leith, private communication). Since that time, numerous artificial viscosity formulations have been proposed for simulating both shocks and turbulence [4, 5, 6, 7, 8, 9, 10]. Over the years however, a rift has developed between shock-capturing (monotonicity-preserving) and turbulence-capturing (large-eddy simulation) methods. Artificial viscosities for shock-capturing typically depend on sound speed, which makes them unsuitable for low Mach number flows. On the other hand, subgrid-scale models, customized for incompressible turbulence, usually fail to capture shocks in a monotonic fashion. The purpose of this paper is to introduce an artificial viscosity suitable for computing shock-turbulence interactions. This is accomplished by extending the model of Cook and Cabot [10] to multi-dimensions.
Download or read book Shock turbulence Interaction and Richtmyer Meshkov Instability in Spherical Geometry written by Ankit Vijay Bhagatwala and published by Stanford University. This book was released on 2011 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt: The canonical problems of shock-turbulence interaction and Richtmyer-Meshkov instability (RMI) are central to understanding the hydrodynamic processes involved in Inertial Confinement Fusion (ICF). Over the last few decades, there has been considerable analytical, computational and experimental work on the planar versions of these problems. In spite of the problem of interest being spherical in nature, there have been few studies in any of the three areas for these problems. It is not clear a priori, that the conclusions drawn from planar versions of these problems carry over to the spherical domain. The research presented here represents a first attempt to understand the hydrodynamic processes involved in an Inertial Fusion Engine (IFE) from capsule implosion to interaction of the resulting shock waves with the chamber gases. To abstract the key hydrodynamic components from the complex physics involved in an IFE, three canonical problems are identified and simulated: Interaction of a blast wave with isotropic turbulence, interaction of a converging shock with isotropic turbulence and RMI in spherical geometry. The last problem is a hydrodynamic abstraction of the capsule implosion itself, while the first two problems attempt to model the late stage interaction of fusion induced shock waves with chamber gases. On the shock-turbulence front, the study primarily focuses on the effect of shock strength relative to background turbulence on vorticity dynamics, which forms the cornerstone of any turbulence simulation. The effect of turbulence on shock structure is also characterized. For the converging shock, the maximum compression achieved in presence of turbulence is compared with that for a pure shock. For spherical RMI, focus is on evolution of the mixing layer and growth in vorticity and turbulent kinetic energy for different incident shock Mach numbers. The effect of interface perturbation on maximum compression achieved, which is one of the most important metrics for feasible ICF, is also considered.
Download or read book Psuedospectral Calculation of Shock Turbulence Interactions written by and published by . This book was released on 1983 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Simulation Strategies for Shock Turbulence Interactions written by and published by . This book was released on 2008 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The computational challenge of predicting shock-turbulence interactions stems from the fundamentally different physics at play. Shock waves are microscopically thin regions wherein flow properties change rapidly over a distance roughly equal to the molecular mean free path; hence, they are essentially strong discontinuities in the flow field. Turbulence, on the other hand, is a chaotic phenomenon with broadband spatial and temporal scales of motion. Most shock-capturing methods rely on strong numerical dissipation to artificially smooth the discontinuity, such that it can be resolved on the computational grid. Unfortunately, the artificial dissipation necessary for capturing shocks has a deleterious effect on turbulence. An additional problem is the fact that shock-capturing schemes are typically based on one-dimensional Riemann solutions that are not strictly valid in multiple dimensions. This can lead to anisotropy errors and grid-seeded perturbations. Other complications arising from upwinding, flux limiting, operator splitting etc., can seriously degrade performance and generate significant errors, especially in multiple dimensions. The purpose of this work is to design improved algorithms, capable of capturing both shocks and turbulence, which also scale to tens of thousands of processors. We have evaluated two new hydrodynamic algorithms, in relation to the widely used WENO method, on a suite of test cases. The new methods, referred to as the 'Compact' and 'Hybrid' schemes, show very promising results.
Download or read book Shock turbulence Interactions in a Reacting Flow written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1992 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Pseudospectral Calculation of Shock Turbulence Interactions written by T. A. Zang and published by . This book was released on 1983 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of Shock turbulence Interaction written by David T. Kiang and published by . This book was released on 1970 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Performance of Low Dissipative High Order Shock capturing Schemes for Shock turbulence Interactions written by Neil D. Sandham and published by . This book was released on 1998 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "Accurate and efficient direct numerical simulation of turbulence in the presence of shock waves represents a significant challenge for numerical methods. The objective of this paper is to evaluate the performance of high order compact and non-compact central spatial differencing employing total variation diminishing (TVD) shock-capturing dissipations as characteristic based filters for two model problems combining shock wave and shear layer phenomena. A vortex pairing model evaluates the ability of the schemes to cope with shear layer instability and eddy shock waves, while a shock wave impingement on a spatially-evolving mixing layer model studies the accuracy of computation of vortices passing through a sequence of shock and expansion waves. A drastic increase in accuracy is observed if a suitable artificial compression formulation is applied to the TVD dissipations. With this modification to the filter step the fourth-order on-compact scheme shows improved results in comparison to second-order methods, while retaining the good shock resolution of the basic TVD scheme. For this characteristic based filter approach, however, the benefits of compact schemes or schemes with higher than fourth order are not sufficient to justify the higher complexity near the boundary and/or the additional computational cost."
Download or read book Shock turbulence Interaction and Richtmyer Meshkov Instability in Spherical Geometry written by Ankit Vijay Bhagatwala and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The canonical problems of shock-turbulence interaction and Richtmyer-Meshkov instability (RMI) are central to understanding the hydrodynamic processes involved in Inertial Confinement Fusion (ICF). Over the last few decades, there has been considerable analytical, computational and experimental work on the planar versions of these problems. In spite of the problem of interest being spherical in nature, there have been few studies in any of the three areas for these problems. It is not clear a priori, that the conclusions drawn from planar versions of these problems carry over to the spherical domain. The research presented here represents a first attempt to understand the hydrodynamic processes involved in an Inertial Fusion Engine (IFE) from capsule implosion to interaction of the resulting shock waves with the chamber gases. To abstract the key hydrodynamic components from the complex physics involved in an IFE, three canonical problems are identified and simulated: Interaction of a blast wave with isotropic turbulence, interaction of a converging shock with isotropic turbulence and RMI in spherical geometry. The last problem is a hydrodynamic abstraction of the capsule implosion itself, while the first two problems attempt to model the late stage interaction of fusion induced shock waves with chamber gases. On the shock-turbulence front, the study primarily focuses on the effect of shock strength relative to background turbulence on vorticity dynamics, which forms the cornerstone of any turbulence simulation. The effect of turbulence on shock structure is also characterized. For the converging shock, the maximum compression achieved in presence of turbulence is compared with that for a pure shock. For spherical RMI, focus is on evolution of the mixing layer and growth in vorticity and turbulent kinetic energy for different incident shock Mach numbers. The effect of interface perturbation on maximum compression achieved, which is one of the most important metrics for feasible ICF, is also considered.
Download or read book Studies of Shock Wave Interactions with Homogeneous and Isotropic Turbulence written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-11-02 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: A nearly homogeneous nearly isotropic compressible turbulent flow interacting with a normal shock wave has been studied experimentally in a large shock tube facility. Spatial resolution of the order of 8 Kolmogorov viscous length scales was achieved in the measurements of turbulence. A variety of turbulence generating grids provide a wide range of turbulence scales. Integral length scales were found to substantially decrease through the interaction with the shock wave in all investigated cases with flow Mach numbers ranging from 0.3 to 0.7 and shock Mach numbers from 1.2 to 1.6. The outcome of the interaction depends strongly on the state of compressibility of the incoming turbulence. The length scales in the lateral direction are amplified at small Mach numbers and attenuated at large Mach numbers. Even at large Mach numbers amplification of lateral length scales has been observed in the case of fine grids. In addition to the interaction with the shock the present work has documented substantial compressibility effects in the incoming homogeneous and isotropic turbulent flow. The decay of Mach number fluctuations was found to follow a power law similar to that describing the decay of incompressible isotropic turbulence. It was found that the decay coefficient and the decay exponent decrease with increasing Mach number while the virtual origin increases with increasing Mach number. A mechanism possibly responsible for these effects appears to be the inherently low growth rate of compressible shear layers emanating from the cylindrical rods of the grid. Briassulis, G. and Agui, J. and Watkins, C. B. and Andreopoulos, Y. Langley Research Center...
Download or read book Direct Numerical Simulation and Analysis of Shock Turbulence Interaction written by Sangsan Lee and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Shock Turbulence Interaction in the Presence of Mean Shear written by K. Mahesh and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interaction of Isotropic Turbulence written by Stanford University. Thermosciences Division. Thermosciences Division and published by . This book was released on 1992 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies of Shock Wave Interactions with Homogeneous and Isotropic Turbulence written by G. Briassulis and published by . This book was released on 1998 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theoretical Investigation of 3 D Shock Wave turbulent Boundary Layer Interactions written by Doyle D. Knight and published by . This book was released on 1988 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
