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Author : T. S. Lund
Publisher :
ISBN 13 :
Total Pages : 44 pages
Book Rating : 4.:/5 (92 download)
Download or read book Direct numerical simulation of weakly stratified turbulent wake written by T. S. Lund and published by . This book was released on 2014 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : A.S. Ginevsky
Publisher : Springer Science & Business Media
ISBN 13 : 3642017606
Total Pages : 166 pages
Book Rating : 4.6/5 (42 download)
Download or read book Vortex wakes of Aircrafts written by A.S. Ginevsky and published by Springer Science & Business Media. This book was released on 2009-07-07 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigation of vortex wakes behind various aircraft, especially behind wide bodied and heavy cargo ones, is of both scientific and practical in terest. The vortex wakes shed from the wing’s trailing edge are long lived and attenuate only atdistances of10–12kmbehindthe wake generating aircraft. The encounter of other aircraft with the vortex wake of a heavy aircraft is open to catastrophic hazards. For example, air refueling is adangerous operationpartly due to thepossibility of the receiver aircraft’s encountering the trailing wake of the tanker aircraft. It is very important to know the behavior of vortex wakes of aircraft during theirtakeoff andlanding operations whenthe wakes canpropagate over the airport’s ground surface and be a serious hazard to other depart ing or arriving aircraft. This knowledge can help in enhancing safety of aircraft’s movements in the terminal areas of congested airports where the threat of vortex encounters limits passenger throughput. Theoreticalinvestigations of aircraft vortex wakes arebeingintensively performedinthe major aviationnations.Usedforthispurpose are various methods for mathematical modeling of turbulent flows: direct numerical simulation based on the Navier–Stokes equations, large eddy simulation using the Navier–Stokes equations in combination with subrigid scale modeling, simulation based on the Reynolds equations closed with a differential turbulence model. These approaches are widely used in works of Russian and other countries’ scientists. It should be emphasized that the experiments in wind tunnels and studies of natural vortex wakes behind heavy and light aircraft in flight experiments are equally important.
Author : Raphael Gotthard Harald Arlitt
Publisher : Cuvillier Verlag
ISBN 13 : 3865373461
Total Pages : 221 pages
Book Rating : 4.8/5 (653 download)
Download or read book Analysis of Weakly Compressible Turbulence Using Symmetry Methods and Direct Numerical Simulation written by Raphael Gotthard Harald Arlitt and published by Cuvillier Verlag. This book was released on 2005 with total page 221 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Matthew Bronson De Stadler
Publisher :
ISBN 13 : 9781303429675
Total Pages : 241 pages
Book Rating : 4.4/5 (296 download)
Download or read book High Resolution Simulation of the Turbulent Wake Behind a Sphere in a Stratified Fluid written by Matthew Bronson De Stadler and published by . This book was released on 2013 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: The wake of a bluff body is significantly modified by the presence of a stable density stratification. Buoyancy effects introduce a complex coupling between kinetic and potential energy which results in a significantly longer wake lifetime, internal wave radiation, and long lived coherent structures. This dissertation presents results obtained from high resolution numerical simulations of stratified turbulent wakes. The dissertation is divided into two parts. The first part of the dissertation uses the well established temporal approximation to simulate from the near wake to the far wake. In this part of the dissertation, the effect of the Prandtl number on a stratified turbulent wake was considered. For 0.2 Pr
Author : Michael Meredith
Publisher : Elsevier
ISBN 13 : 0128215135
Total Pages : 386 pages
Book Rating : 4.1/5 (282 download)
Download or read book Ocean Mixing written by Michael Meredith and published by Elsevier. This book was released on 2021-09-16 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ocean Mixing: Drivers, Mechanisms and Impacts presents a broad panorama of one of the most rapidly-developing areas of marine science. It highlights the state-of-the-art concerning knowledge of the causes of ocean mixing, and a perspective on the implications for ocean circulation, climate, biogeochemistry and the marine ecosystem. This edited volume places a particular emphasis on elucidating the key future questions relating to ocean mixing, and emerging ideas and activities to address them, including innovative technology developments and advances in methodology. Ocean Mixing is a key reference for those entering the field, and for those seeking a comprehensive overview of how the key current issues are being addressed and what the priorities for future research are. Each chapter is written by established leaders in ocean mixing research; the volume is thus suitable for those seeking specific detailed information on sub-topics, as well as those seeking a broad synopsis of current understanding. It provides useful ammunition for those pursuing funding for specific future research campaigns, by being an authoritative source concerning key scientific goals in the short, medium and long term. Additionally, the chapters contain bespoke and informative graphics that can be used in teaching and science communication to convey the complex concepts and phenomena in easily accessible ways. Presents a coherent overview of the state-of-the-art research concerning ocean mixing Provides an in-depth discussion of how ocean mixing impacts all scales of the planetary system Includes elucidation of the grand challenges in ocean mixing, and how they might be addressed
Author : Jianping Zhu
Publisher : BoD – Books on Demand
ISBN 13 : 9533074302
Total Pages : 576 pages
Book Rating : 4.5/5 (33 download)
Download or read book Computational Simulations and Applications written by Jianping Zhu and published by BoD – Books on Demand. This book was released on 2011-10-26 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this book is to introduce researchers and graduate students to a broad range of applications of computational simulations, with a particular emphasis on those involving computational fluid dynamics (CFD) simulations. The book is divided into three parts: Part I covers some basic research topics and development in numerical algorithms for CFD simulations, including Reynolds stress transport modeling, central difference schemes for convection-diffusion equations, and flow simulations involving simple geometries such as a flat plate or a vertical channel. Part II covers a variety of important applications in which CFD simulations play a crucial role, including combustion process and automobile engine design, fluid heat exchange, airborne contaminant dispersion over buildings and atmospheric flow around a re-entry capsule, gas-solid two phase flow in long pipes, free surface flow around a ship hull, and hydrodynamic analysis of electrochemical cells. Part III covers applications of non-CFD based computational simulations, including atmospheric optical communications, climate system simulations, porous media flow, combustion, solidification, and sound field simulations for optimal acoustic effects.
Author : National Research Council
Publisher : National Academies Press
ISBN 13 : 0309254701
Total Pages : 1018 pages
Book Rating : 4.3/5 (92 download)
Download or read book Twenty-Fourth Symposium on Naval Hydrodynamics written by National Research Council and published by National Academies Press. This book was released on 2003-11-15 with total page 1018 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report is part of a series of reports that summarize this regular event. The report discusses research developments in ship design, construction, and operation in a forum that encouraged both formal and informal discussion of presented papers.
Author : Center for Turbulence Research (U.S.)
Publisher :
ISBN 13 :
Total Pages : 368 pages
Book Rating : 4.F/5 ( download)
Download or read book Studying Turbulence Using Numerical Simulation Databases written by Center for Turbulence Research (U.S.) and published by . This book was released on 1987 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Narsimha Reddy Rapaka
Publisher :
ISBN 13 : 9781339091792
Total Pages : 92 pages
Book Rating : 4.0/5 (917 download)
Download or read book Simulation of Stratified Turbulent Flows in Complex Geometry written by Narsimha Reddy Rapaka and published by . This book was released on 2015 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: Direct and Large Eddy Simulation approaches are used to study internal tide generation and turbulence at a model topography. A three dimensional finite difference code using an immersed boundary method is developed to simulate stratified turbulent flows over complex geometry on a Cartesian grid. The thesis is comprised of two phases. In the first phase, a mixed spectral/finite difference code is used to solve the governing equations in generalized coordinates. Direct and large eddy simulations are performed using a body fitted grid (BFG) to study the internal waves generated by the oscillation of a barotropic tide over a model ridge of triangular shape. The objective is to assess the role of nonlinear interactions including turbulence in situations with low tidal excursion number. The criticality parameter, defined as the ratio of the topographic slope to the characteristic slope of the tidal rays, is varied from subcritical to supercritical values. The barotropic tidal forcing is also systematically increased. In laminar flow at low forcing, numerical results of the energy conversion agree well compared to linear theory in subcritical and supercritical cases but not at critical slope angle. In critical and supercritical cases with higher forcing, there are convective overturns, turbulence and significant reduction (as much as 25%) of the radiated wave flux with respect to laminar flow results. The phase dependence of turbulence within a tidal cycle is examined and found to differ substantially between the ridge slope and the ridge top where the beams from the two sides cross. In the second phase, a sharp-interface Immersed Boundary Method (IBM) is developed to simulate high Reynolds number density-stratified turbulent flows in complex geometry. The basic numerical scheme corresponds to a central second-order finite difference method, third-order Runge-Kutta integration for the advective terms and an alternating direction implicit (ADI) scheme for the viscous and diffusive terms. Both direct numerical simulation (DNS) and large eddy simulation (LES) approaches are considered. The focus is on accurate computation of the internal gravity wave field and turbulence near an underwater obstacle in a model problem where a tide oscillates over the obstacle. Methods to enhance the mass conservation and numerical stability of the solver to simulate high Reynolds number flows are discussed. The solver is validated using Direct Numerical Simulations (DNS) of channel flow with and without stratification, and tidal flow over a laboratory-scale (order of few meters) smoothed triangular ridge. The results including baroclinic energy flux, mean flow properties and turbulent kinetic energy agree reasonably well with our previous results obtained using a body-fitted grid (BFG). The deviation of IBM results from BFG results is found to increase with increasing steepness of the topography relative to the internal wave propagation angle. LES is performed on a large scale ridge, of the order of few kilometers in length, at significantly larger Reynolds number. A non-linear drag law is utilized to parameterize turbulent losses due to bottom friction. The large scale problem exhibits qualitatively similar behavior to the laboratory scale problem with some differences: slightly larger intensification of the boundary flow and somewhat higher nondimensional values for conversion, baroclinic wave flux and turbulent kinetic energy. The phasing of wave breaking and turbulence exhibits little difference between small and large scale obstacles. We conclude that IBM is a viable approach to the simulation of internal waves and turbulence in high Reynolds number stratified flows over topography.
Author : Alex. C. Warn-Varnas
Publisher :
ISBN 13 :
Total Pages : 33 pages
Book Rating : 4.:/5 (152 download)
Download or read book Numerical Simulation of Collapsing Turbulent Wakes written by Alex. C. Warn-Varnas and published by . This book was released on 1979 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: The collapse of a partially mixed region generated by a prescribed amount of turbulence deposited on a linearly stratified ambient ocean is studied numerically. Different turbulent closures such as first and second order are used to model the turbulent stresses. The resulting equations are solved numerically in a finite-difference formalism of the primitive form of the equations in a box region several times the size of the mixed region. The resulting maximum observed mean field velocities, densities, and turbulent energies in the fluid are obtained and cross-compared for different closures and numerical methods.
Author : Frank G. Jacobitz
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (11 download)
Download or read book Efficiency of Parallel Direct Numerical Simulations of Turbulent Stratified Shear Flow written by Frank G. Jacobitz and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Gregory P. Brooks
Publisher :
ISBN 13 :
Total Pages : 248 pages
Book Rating : 4.:/5 (423 download)
Download or read book Numerical Simulation of a Planar Turbulent Wake in Arbitrary Pressure Gradient written by Gregory P. Brooks and published by . This book was released on 1999 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Jan Gerard Wissink
Publisher :
ISBN 13 : 9789036705349
Total Pages : 135 pages
Book Rating : 4.7/5 (53 download)
Download or read book Direct Numerical Simulation of Turbulence written by Jan Gerard Wissink and published by . This book was released on 1995 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : John Cannon
Publisher : CRC Press
ISBN 13 : 1420014978
Total Pages : 209 pages
Book Rating : 4.4/5 (2 download)
Download or read book Mathematical and Physical Theory of Turbulence, Volume 250 written by John Cannon and published by CRC Press. This book was released on 2006-06-15 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although the current dynamical system approach offers several important insights into the turbulence problem, issues still remain that present challenges to conventional methodologies and concepts. These challenges call for the advancement and application of new physical concepts, mathematical modeling, and analysis techniques. Bringing together ex
Author : Amid Ansari
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (11 download)
Download or read book Direct Numerical Simulation of Turbulent Mixing Layers written by Amid Ansari and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studying Turbulence Using Numerical Simulation Databases written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Sheel Nidhan
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (137 download)
Download or read book Simulation-based Analyses of Turbulent Wakes written by Sheel Nidhan and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent wakes are pervasive in man-made and natural environments. In the ocean and the atmosphere, these wakes interact with the background ambient stratification to give rise to a myriad of interesting phenomena, e.g., multistage decay of mean and turbulence, long-lived coherent structures, and the appearance of internal gravity waves, to name a few. With the rise in supercomputing power, high-fidelity numerical simulations have become an increasingly feasible way to investigate the phenomenology of these wakes. As these simulations become commonplace in research, there is an increased focus on the use of data-driven techniques to uncover the rich dynamics from the obtained datasets. This dissertation is an examination of turbulent wakes using data-driven techniques and numerical simulations. In the first part, spectral proper orthogonal decomposition is used to investigate a turbulent disk wake database at Re = 5 x 104 and Fr = [infinity], 10, 2. We first study the evolution of the vortex shedding mode and double helix mode in the unstratified wake (Fr = [infinity]), building on and refining the previous experimental studies. Thereafter, the SPOD analysis of the stratified wakes is performed that uncovers two new results: (a) coherence originating at the body gets stronger and lives longer with progressively increasing stratification levels and (b) for Fr [greater than and approximately equal to] 2, vortex shedding is the dominant mechanism of internal gravity wave generation. In the second part of the work, large eddy simulations (LES) are used to investigate the flow past a prolate 6:1 spheroid. Firstly, high-resolution hybrid simulation is used to simulate the far wake of a 6:1 spheroid at 0-degree angle of attack and Re = 105, Fr = 2 and 10. The far wake is compared to the above-mentioned disk database. The spheroid wakes show differences in locations at which mean wake transitions take place. These differences are explained in light of energy budgets. Secondly, large eddy simulations of flow past a 6:1 spheroid at Re = 5000, Fr = [infinity], 6, 1.9, 1, and a moderate angle of attack [alpha] = 10[superscript circle] are carried out. Body forces, mean wake and vorticity dynamics, and flow spectra are analyzed in detail and presented in the dissertation.
