Download or read book Numerical Computations of Turbulence Amplification in Shock Wave Interactions written by Thomas A. Zang and published by . This book was released on 1983 with total page 40 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 Interaction of Turbulence with Complex Shock Waves written by and published by . This book was released on 1994 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: Linear analysis and direct numerical simulation (DNS) are used to study the interaction of a shock wave with a turbulent flow. Effects central to shock wave/boundary layer interaction are identified and explained. The quantitative importance of the turbulence anisotropy and the shock oblique angle is demonstrated. Drop in Reynolds shear stress across a normal shock is shown. The implication for Reynolds stress models is discussed. The role of dilatational turbulent fluctuations on turbulence amplification is studied in detail. An explanation is suggested for lower amplification reported in wind-tunnel studies. Linear analysis & DNS are used to demonstrate the considerable influence of entropic fluctuations on turbulence evolution across a shock. Positive correlation between u' and T ' suppress amplification while negative correlation enhances it. Invalidity of Morkovin's hypothesis is demonstrated. A high order scheme is developed to allow strong shock/turbulence interaction. Results are presented for isotropic turbulence/normal shock interaction. (AN).

Download or read book Interaction of Isotropic Turbulence with a Shock Wave written by S. Lee and published by . This book was released on 1992 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Investigation of Turbulence Behavior in Shock Wave Turbulent Boundary Layer Interactions written by and published by . This book was released on 1991 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary objective of this research is to enhance our understanding of the flow field physics associated with shock wave turbulent boundary layer interactions and thereby enable more accurate predictive models to be developed. It is widely recognized that shock wave turbulent boundary layer interactions are very important in a variety of high speed aerodynamic applications and yet, despite much attention to this topic in the past, the dynamic mechanisms involved remain poorly understood. The compression ramp generated shock wave turbulent boundary layer interaction is experimentally investigated in this study. It is a primary objective of this research to isolate the mechanism(s) responsible for the amplification of turbulent stresses through the shock. The interplay between the combined effects of bulk compression, concave curvature, 'direct' amplification and pressure gradient will be clarified. In addition, the dynamic mechanism(s) responsible for shock wave oscillation and the role this oscillation plays in the turbulent stress amplification through the shock will also be examined. Measurements documenting the mechanism of turbulent stress relaxation downstream of shock are also obtained.

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.

Download or read book Numerical Study of Variable Density Flow Interaction with a Shock Wave written by Yifeng Tian and published by . This book was released on 2019 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamental understanding and modeling of multi-fluid miscible Shock-Turbulence Interaction (STI) and the corresponding post-shock turbulence are critically important to many different applications, such as supersonic combustion, nuclear fusion, and astrophysics. This thesis presents a comprehensive study of the multi-fluid Shock-Turbulence flow using accurate flow-resolving, shock-capturing, and shock-resolving simulations. The objective is to develop a better understanding of underlying mechanisms of the variable density fluid effects on shock-turbulence interactions, post-shock turbulence evolution and mixing in high speed flows. Theoretical and numerical analyses of data confirm that all turbulence scales as well as the STI are well captured by the computational method, which is based on a high order hybrid monotonicity preserving-compact finite difference scheme. Linear Interaction Approximation (LIA) convergence tests are conducted to show that shock-capturing numerical simulations exhibit similar converging trend to LIA predictions as more demanding shock-resolving Direct Numerical Simulations (DNS) method. The effects of density variations on STI are studied first by comparing the "Eulerian" results obtained from both Eulerian (grid) and Lagrangian (particle) data for a multi-fluid mixture with the corresponding single-fluid results. The comparison shows that the turbulence amplification by the normal shock wave is much higher and the reduction in turbulence length scales is more significant when strong density variations are present. Turbulent mixing enhancement by the shock is also increased and stronger mixing asymmetry in the post-shock region is observed when there are significant density variations. The dominating mechanisms behind STI influence on post-shock turbulence and mixing are identified by analyzing the transport equations for the Reynolds stresses, vorticity, normalized mass flux, and density specific volume covariance. Statistical analyses of the velocity gradient tensor (VGT) show that the density variations also significantly change the turbulence structure and flow topology. Compared to the single-fluid case, the correlation between rotation and strain is found to be weaker in the multi-fluid case, which is shown to be the result of complex role density plays when the flow passes through the shock. Furthermore, a stronger symmetrization of the joint PDF of second and third invariants of the anisotropic velocity gradient tensor, as well as the PDF of the vortex stretching contribution to the enstrophy equation, are observed in the multi-fluid case. Lagrangian dynamics of the VGT and its invariants are studied by considering particle residence times in different flow regions and the conditional mean rate of change vectors. The pressure Hessian contributions to the VGT invariants transport equations are shown to be strongly affected by the shock wave and local density, making them critically important to the flow dynamics and turbulence structure. Lagrangian statistics of non-inertial particles in post-shock turbulence show that the single-particle dispersion rate and anisotropy can be correlated to the development of post-shock Reynolds stress. The particle dispersion in the streamwise direction is found to be non-Gaussian, with the skewness of the dispersion PDF dependent on the density variations. Lagrangian integral time scales of fluid particles with different densities are obtained from velocity autocorrelation functions. Particle pair dispersion generally follows the temporal scaling for isotropic turbulence. In this thesis, the propagation of shock waves in non-uniform density media is also studied. Theoretical analyses show that in both linear and nonlinear regime, there are similarities in shock propagation in non-uniform density fields generated by fluctuations in entropy and compositional fields. The 1D numerical results are shown to agree well with theoretical solutions obtained from classical Chisnell-Whitham theory for weak shocks and linearly varying density fields. For more significantly varying density profiles, the numerical results deviate from the theoretical solutions and exhibit additional long-wavelength oscillations, which are shown to be related to the re-reflected waves. A simplified model (named CWRW) that includes the effects of re-reflected waves is proposed to compensate for the CW model definitions. The results obtained by the proposed CWRW model show significant improvement over the classical CW model. The three-dimensional (3D) effects concerning the shock propagation in 3D non-uniform density media are studied by considering the wavenumber ratio of the streamwise and spanwise length scales in the density field. The asymptotic limits for wavelength ratio approaching zero and infinity are investigated and used to provide a bound for shock propagation in 3D non-uniform media.

Download or read book Interaction of Isotropic Turbulence with a Shock Wave written by Sangsan Lee and published by . This book was released on 1992 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: As a first step to understand the compressibility effects, interaction of isotropic quasi-incompressible turbulence with a weak shock wave was studied by three-dimensional time-dependent direct numerical simulations. In addition, linear analysis was used to study interaction of isotropic turbulence with shock waves of a wide range of strengths. The effects of the fluctuation Mach number M sub t and the average Mach number M sub 1 superscript u of the upstream turbulence on turbulence statistics were investigated. Both numerical simulations and linear analyses of the interaction show that turbulence is enhanced during the interaction with a shock wave. Turbulent kinetic energy (TKE) and transverse vorticity components are amplified, and turbulent length scales are decreased. The predictions of the linear analyses compare favorably with simulation results for flows with M sub t

Download or read book Studies of Shock Wave Interactions with Homogeneous and Isotropic Turbulence written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-16 with total page 56 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 Shock Wave Interaction with Turbulence written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Shock waves amplify pre-existing turbulence. Shock tube and shock wave boundary layer interaction experiments provide qualitative confirmation. However, shock pressure, temperature, and rapid transit complicate direct measurement. Computational simulations supplement the experimental data base and help isolate the mechanisms responsible. Simulations and experiments, particularly under reflected shock wave conditions, significantly influence material mixing. In these pseudospectral Navier-Stokes simulations the shock wave is treated as either a moving (tracked or fitted) domain boundary. The simulations assist development of code mix models. Shock Mach number and pre-existing turbulence intensity initially emerge as key parameters. 20 refs., 8 figs.

Download or read book On the Interaction Between the Shock Wave Attached to a Wedge and Freestream Disturbances written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-10 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study of the interaction of small amplitude, unsteady, freestream disturbances with a shock wave induced by a wedge in supersonic flow is presented. These disturbances may be acoustic waves, vorticity waves, or entropy waves (or indeed a combination of all three). Their interactions then generate behind the shock disturbances of all three classes, an aspect that is investigated in some detail, our motivation being to investigate possible mechanisms for boundary-layer receptivity, caused through the amplification and modification of freestream turbulence through the shock-body coupling. Also, the possibility of enhanced mixing owing to additional vorticity produced by the shock-body coupling is investigated. Duck, Peter W. and Lasseigne, D. Glenn and Hussaini, M. Y. Unspecified Center...

Download or read book Two dimensional Compression Corner and Planar Shock Wave Interactions with a Supersonic Turbulent Boundary Layer written by C. Herbert Law and published by . This book was released on 1975 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Turbulent Shear Layer Shock Wave Interactions written by J. Delery and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: It was on a proposal of the late Professor Maurice Roy, member of the French Academy of Sciences, that in 1982, the General Assembly of the International Union of Theoretical and Applied Mechanics decided to sponsor a symposium on Turbulent Shear-Layer/Shock-Wave Interactions. This sympo sium might be arranged in Paris -or in its immediate vicinity-during the year 1985. Upon request of Professor Robert Legendre, member of the French Academy of Sciences, the organization of the symposium might be provided by the Office National d'Etudes et de Recherches Aerospatiales (ONERA). The request was very favorably received by Monsieur l'Ingenieur General Andre Auriol, then General Director of ONERA. The subject of interactions between shock-waves and turbulent dissipative layers is of considerable importance for many practical devices and has a wide range of engineering applications. Such phenomena occur almost inevitably in any transonic or supersonic flow and the subject has given rise to an important research effort since the advent of high speed fluid mechanics, more than forty years ago. However, with the coming of age of modern computers and the development of new sophisticated measurement techniques, considerable progress has been made in the field over the past fifteen years. The aim of the symposium was to provide an updated status of the research effort devoted to shear layer/shock-wave interactions and to present the most significant results obtained recently.

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 A Numerical Solution for the Interaction of a Moving Shock Wave with a Turbulent Mixing Region written by William Fred Walker and published by . This book was released on 1966 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulation of a Turbulent Flow Through a Shock Wave written by David Nixon and published by . This book was released on 1989 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the results of research into the interactions between shock waves and turbulent flows using numerical simulations. The research was conducted at transonic speeds with a normal shock wave and two dimensional turbulence, making use of existing knowledge and computational methods for developing insight to the shock/turbulence interaction. The results indicate that the shock has a significant effect on the turbulence. The shock produces a jump in the turbulence statistics, with a long relaxation distance to return to unshocked values. The turbulence kinetic energy is increased by as much as 30 percent by the shock. The density-velocity correlation becomes important during the shock jump and is greatly increased over the case without a shock. On the other hand, the pressure-velocity correlation is not so important. The shock speed and ripple were found to be important factors in determining the turbulence downstream of a shock wave. Shock speed and ripple correlations are the same size as other important turbulence correlations. The work must be extended to higher Mach numbers and three-dimensional turbulence, with oblique shocks and shear flows. The shock ripple may be more important for oblique shocks because of the larger v component. (jhd).

Download or read book Study of the Pressure Rise Across Shock Waves Required to Separate Laminar and Turbulent Boundary Layers written by Coleman duP. Donaldson and published by . This book was released on 1952 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt: