Concept of hydrodynamic stability. Stability of fluid motion in time. Critical parameters for onset of. PDF In the present book we try to give a panoramic view of the origin of turbulence in near-wall shear layers by binding its different aspects for prototypical.
! The Origin Of Turbulence In Near Wall Flows
The origin of turbulence in fluids is a long-standing problem being in focus of researches through decades due to its great importance in a variety of engineering applications. This paper is concern to a review of new findings in the field of laminar-turbulent transition of near-wall flows. The Origin of Species Charles Darwin The origin of turbulence in fluids is a long- standing problem and has been the focus of research for decades due to its.
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The minimal flow unit in near-wall turbulence | Journal of Fluid Mechanics | Cambridge Core
Grek, A. Dovgal, Victor V. Springer, Softcover reprint of hardcover 1. Coherent structures in wall turbulence transport momentum and provide a J. Fluid Mech. Keywords: 3-D near-wall turbulent flow, Streamwise corner, Boundary-layer interaction, Experiment, Computation. Modeling and prediction of near wall turbulent flows. Sricharan Srinath.. The trajectories of individual heat or mass markers are tracked, generating a probability distribution function that describes the behavior of instantaneous point sources of a scalar in the turbulent field.
The effect of the Prandtl or Schmidt number on turbulent dispersion is examined, with emphasis on the dispersion pattern.
- Experimental investigation of turbulent boundary layers over steep two-dimensional elevations;
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Results for Prandtl or Schmidt numbers between 0. For an instantaneous source at the channel center, it is found that there are two zones of cloud development: one where molecular diffusion plays a role at very small times early stage of the dispersion , and one where turbulent convection dominates. The asphericity of the scalar marker cloud is found to increase monotonically, in contrast to published results for isotropic, homogenous turbulence, where the asphericity goes through a maximum.
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- The Origin of Turbulence in Near-Wall Flows [electronic resource];
- Near-wall statistics of a turbulent pipe flow at shear Reynolds numbers up to 40 000.
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The slope of the lines changes from representing the maximum mean fluid velocity at small times to representing the bulk fluid velocity in the channel at longer times. Viscous wall units are used for space and time. At times less than 50, the value of asphericity is less than 0. Bowers and Leo G. Its performance in initial numerical tests was remarkable, which led to analytical studies and further numerical tests, all of which provided excellent results. Abstract Turbulence intensity profiles are compared for smooth- and rough-wall pipe flow measurements made in the Princeton Superpipe.
The profile development in the transition from hydraulically smooth to fully rough flow displays a propagating sequence from the pipe wall towards the pipe axis. The [ Turbulence intensity profiles are compared for smooth- and rough-wall pipe flow measurements made in the Princeton Superpipe. The scaling of turbulence intensity with Reynolds number shows that the smooth- and rough-wall level deviates with increasing Reynolds number.
We quantify the correspondence between turbulence intensity and the friction factor. The arithmetic mean AM is used for the pipe area TI. Abstract This paper presents a numerical study of high wavenumber coherent structure evolution in boundary layer transition flow using recently-developed high order Combined compact difference schemes with non-uniform grids in the wall-normal direction for efficient simulation of such flows.
The study focuses on a [ This paper presents a numerical study of high wavenumber coherent structure evolution in boundary layer transition flow using recently-developed high order Combined compact difference schemes with non-uniform grids in the wall-normal direction for efficient simulation of such flows. The study focuses on a simulation of an Adverse-Pressure-Gradient APG boundary layer transition induced by broadband disturbance corresponding to the experiment of Borodulin et al.
Journal of Turbulence, , 7, pp. The results support the experimental observation that although the coherent structures seen during transition to turbulence have asymmetric shapes and occur in a random pattern, their local evolutional behaviors are quite similar. Further calculated local wavelet spectra of these coherent structures are also very similar.
These observations help to shed light on the generation of turbulence, which is dominated by high wavenumber coherent structures. The vertical axis is the Fourier amplitude while the horizontal axis show frequency range up to 6 times the TS frequency of After that improvement, the computational burden stays unchanged while the accuracy of approximations increases in some of the cases very significantly.
Abstract Solving two-dimensional compressible turbulence problems up to a resolution of 16, 2 , this paper investigates the characteristics of two promising computational approaches: i an implicit or numerical large eddy simulation ILES framework using an upwind-biased fifth-order weighted essentially non-oscillatory WENO reconstruction [ Solving two-dimensional compressible turbulence problems up to a resolution of 16, 2 , this paper investigates the characteristics of two promising computational approaches: i an implicit or numerical large eddy simulation ILES framework using an upwind-biased fifth-order weighted essentially non-oscillatory WENO reconstruction algorithm equipped with several Riemann solvers, and ii a central sixth-order reconstruction framework combined with various linear and nonlinear explicit low-pass spatial filtering processes.
Our primary aim is to quantify the dissipative behavior, resolution characteristics, shock capturing ability and computational expenditure for each approach utilizing a systematic analysis with respect to its modeling parameters or parameterizations. The relative advantages and disadvantages of both approaches are addressed for solving a stratified Kelvin-Helmholtz instability shear layer problem as well as a canonical Riemann problem with the interaction of four shocks.
The comparisons are both qualitative and quantitative, using visualizations of the spatial structure of the flow and energy spectra, respectively.
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We observe that the central scheme, with relaxation filtering, offers a competitive approach to ILES and is much more computationally efficient than WENO-based schemes. Note that we use periodic boundary conditions on all sides for the DSL problem while using open boundary conditions in all directions for the RSI test case. Note the phase difference in the solutions once it transitions to turbulence. Note absence of smaller structures in the coarse grid runs implying spatial filtering being performed implicitly.
Notice differences in dissipative behavior from presence of vortical structures.
Review Jump to: Editorial , Research. Open Access Review. Abstract The time relaxation model has proven to be effective in regularization of Navier—Stokes Equations. Authors: J. Imprint: Academic Press. Published Date: 1st January Page Count: Flexible - Read on multiple operating systems and devices. Easily read eBooks on smart phones, computers, or any eBook readers, including Kindle. When you read an eBook on VitalSource Bookshelf, enjoy such features as: Access online or offline, on mobile or desktop devices Bookmarks, highlights and notes sync across all your devices Smart study tools such as note sharing and subscription, review mode, and Microsoft OneNote integration Search and navigate content across your entire Bookshelf library Interactive notebook and read-aloud functionality Look up additional information online by highlighting a word or phrase.
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Free Shipping Free global shipping No minimum order. Preface Acknowledgments Chapter 1. Powered by. You are connected as.