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Monday, April 20, 2020 | History

3 edition of Vortex tubes in turbulent flows found in the catalog.

Vortex tubes in turbulent flows

Vortex tubes in turbulent flows

identification, representation, reconstruction

by

  • 212 Want to read
  • 26 Currently reading

Published by Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, National Technical Information Service, distributor in Hampton, Va, [Springfield, Va .
Written in English


Edition Notes

StatementDavid C. Banks, Bart A. Singer.
SeriesNASA contractor report -- 194900., ICASE report -- no. 94-22., NASA contractor report -- NASA CR-194900., ICASE report -- no. 94-22.
ContributionsSinger, Bart A., Institute for Computer Applications in Science and Engineering.
The Physical Object
FormatMicroform
Pagination1 v.
ID Numbers
Open LibraryOL14667753M

We review the progress on the theory and applications of the vortex-surface field (VSF). The VSF provides a systematic Lagrangian-based framework for the identification, characterization, and modeling of flow structures. From the theoretical perspective, the vorticity is simplified to a scalar field as the VSF. The VSF isosurface is a vortex surface consisting of vortex : Yue Yang.


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Vortex tubes in turbulent flows Download PDF EPUB FB2

Vortex Tubes in Turbulent Flows: Identification, Representation, Reconstruction Article (PDF Available) July with 75 Reads How we measure 'reads'. Vortex Tubes in Turbulent Flows: Identification, Representation, Reconstruction David C. Banks * Institute for Computer Applications in Science and Engineering Mail Stop C, NASA Langley Research Center Hampton, VA Bart A.

Singer ** High Technology Corporation Mail StopNASA Langley Research Center Hampton, VA ABSTRACTFile Size: KB. Quasi-equilibrium turbulent flow-fields are obtained after long-time integration of the governing equations written in primitive variables using adaptive spectral domain decomposition method.

The coherent vortex tubes are extracted from the vorticity and potential vorticity fields, using a nonlinear filtering in wavelet space. Quasi-equilibrium turbulent flow-fields are obtained after long-time integration of the governing equations written in primitive variables using adaptive spectral domain decomposition method.

The coherent vortex tubes are extracted from the vorticity and potential vorticity fields, using a nonlinear filtering in wavelet : Marie Farge, Alexandre Azzalini, Alex Mahalov, Basil Nicolaenko, Frank Tse, Giulio Pellegrino, Kai S.

The vortex tube, also known as the Ranque-Hilsch vortex tube, is a mechanical device that separates a compressed gas into hot and cold streams. The gas emerging from the "hot" end can reach temperatures of °C ( °F), and the gas emerging from the "cold end" can reach −50 °C (−58 °F). It has no moving parts.

Pressurised gas is injected tangentially into a swirl. Vortex flow refers to localized swirling or stagnant blood flow that has separated from the central streamlines within a vortices, also called flow eddies, frequently occur at vascular bifurcations and distal to areas of turbulent regions, areas of vortex flow are composed of slowly moving currents and streamlines that are not random but are often.

Get this from a library. Vortex tubes in turbulent flows: identification, representation, reconstruction. [David C Banks; Bart A Singer; Institute for. The study of vortex motion is of great interest to fluid and gas dynamics: since all real flows are vortical in nature, applications of the vortex theory are extremely diverse, many of them (e.g Author: Wolfgang Kollmann.

Long-lived vortex tubes have been extensively observed in turbulent flows, both in direct numerical simulations and in laboratory experiments. In order to investigate the mechanism of formation of these tubes, we have integrated by spectral method, the unforced Navier-Stokes equations for an incompressible flow at Reynolds number (computed at Author: T.

Passot, H. Politano, P. Sulem, J. Angilella, M. Meneguzzi. Vortex flow meters are a direct type of flow-measuring device with operating fundamentals based on the Von Karman Vortex Street principle.

In this instrument, a bluff body or shedder bar is arranged Vortex tubes in turbulent flows book the center of flow path.

When the fluid passes through it, disturbances in the flow called vortices are alternately formed on both sides of the shedder. Compressed air, normally PSlG ( - BAR), is ejected tangentially through a generator into the vortex spin up to 1, RPM, this air stream revolves toward the hot end where some escapes through the control remaining air, still spinning, is forced back through the center of this outer vortex.

In fluid dynamics, a vortex (plural vortices/vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in the wake of a boat, and the winds surrounding a tropical cyclone, tornado or dust devil.

Vortices are a major component of turbulent flow. Hi. I did my PhD research on LES of developing turbulence in trailing vortices. Theses vortices are modelled using common models which are also applicable to cyclones, i.e.

the 2D Lamb-Oseen model, and the 3D Batchelor vortex (also Vortex tubes in turbulent flows book as q-vortex) with axial flow. A control valve in the hot air exhaust adjusts temperatures, flows and refrigeration over a wide range. [12] Vortex tubes are used for cooling of cutting tools (lathes and mills, both manually-operated and CNC machines) during machining.

The vortex tube is well-matched to this application: machine shops generally already use compressed air, and. Simulations have shown the importance of vortex tube interactions in mechanisms of acoustic wave excitation on the Sun.

In this paper, we investigate the mechanisms of formation of vortex tubes in highly turbulent convective flows near the solar surface by using realistic radiative hydrodynamic large-eddy simulations. Buy Trkal Flows and the Emergence of Metastable Streamline-Vortex Tubes: A Model for 3-D Large Scale Structures Formation on FREE SHIPPING on qualified orders.

Vortex lines, tubes, sheets, and concentrated vortices are analyzed, and the fundamental vorticity theorems are formulated. Chapter 12 focuses on turbulent mixing in free-surface flows. Models are developed for multi-dimensional flows, and methods for the estimation of the associated mixing coefficients are presented.

Free Surface Flow. This monograph presents the microscales of complex (buoyant, thermocapillary, two-phase, reacting, radiating, pulsating, etc.) turbulent flows and interprets heat and mass transfer correlations in terms of these scales. The author introduces a general methodology for the development of microscales for complex turbulent flows.

Then he provides, by these scales, a. These notes deal both with vortex dynamics and with the turbulent motion in °uids, with emphasis on the latter. The reason why the two subjects are brought together in a single course will become clear after chapters 2 and 3, which contain most of the material on vorticity.

In the mean time, you should take on faith that the reasonFile Size: 1MB. Part I Vortex structure, stability and evolution --Simulation of vortex sheet roll-up: chaos, azimuthal waves, ring merger / Robert Krasny, Keith Lindsay, Monika Nitsche 3 --Merging of non-symmetric Burgers vortices / Keith Higgins, M.S.

Chong, Andrew Ooi 13 --Effect of stretching on vortices with axial flow / Maurice Rossi, Ivan Delbende. An investigation into the vortex formation in a turbulent fluid with an application in tropical storm generation By Kaushik Majumdar Electronics & Communication Sciences Unit, Indian Statistical Institute,B.

Road, Calcutta –India The present work discusses about a possible physical interpretation of the occurrence of. A new classification method for structures in turbulent flow is proposed and applied to the analysis of homogeneous isotropic turbulence.

The criteria for the classification of the structures into three groups, namely, the group of structures similar to the core region of the Burgers’ vortex tube in which vorticity is predominant, that of the structures similar to the Cited by:   The Highest thermal performance enhancement (TPE) was noticed for α = 10°, S = 20mm, BR = for turbulent flows.

To obtain qualitative information on the flow behavior and vortex structures, flow was visualized by laser sheet using smoke as a tracer supplied at the entrance of the test : Md. Islam, Z. Chong, S. Bojanampati. Here, vortex-induced vibration of an array of elastically supported tubes is simulated in two dimensions by using a flow-induced vibration analysis program, which was developed to evaluate flow-induced vibration in various components such as heat exchangers.

From comparison of calculated results and experimental data, the following points are seen. [2] Dommermuth, D.G.

() The Laminar Interactions of a Pair of Vortex Tubes with a Free Surface. of Fluid Mech.,91– [3] Dommermuth, D.G. (a) Efficient simulation of short- and long-wave interactions with applications to capillary waves.

Random vortex methods are applied to the analysis of boundary layer instability in two and three space dimensions. A thorough discussion of boundary conditions is given. In two dimensions, the results are in good agreement with known facts. In three dimensions, a new version of the method is introduced, in which the computational elements are vortex by: operated vortex tube, the swirl velocity distributions near the hot end in both vortex tubes indicate the outwards flow and formation of a flow re-circulation region known as the multi-circulation.

Calculations of the volumetric flow rate along the vortex tube indicate the existence and locations of the cold core and the Size: 1MB. $\begingroup$ LES: Only the “Large” turbulent scales are resolved.

The “smaller” scales are modelled. RANS: All the turbulent scales are modelled. In LES, you solve a filtered version of the Navier-Stokes Equations along with another equation to represent the turbulent small scales In RANS, you solve the averaged version of the Navier-Stokes equation along with another.

Modern experiments and numerical simulations show that the long-known coherent structures in turbulence take the form of elongated vortex tubes and vortex sheets. The evolution of vortex tubes may result in spiral structures which can be associated with the spectral power laws of turbulence.

The. Vortex is a fluid structure such that any fluid particle present within that structure experiences a ‘rotation’. A vortex is associated with a vector called vorticity, just like a particle in motion is associated with a vector called velocity. Vor. The following three approaches are applied most frequently in numerical calculation of turbulent flows: (1) The most frequent, but also most simple averaging is with respect to time.

However, this approach is based on the assumption that the turbulent velocity fluctuations are distributed stochastically, meaning there is a constant mean Size: KB.

turbulent model, as well as the lack of systematic comparative analysis. LES model for the vortex tube simulation is hardly used in the present literatures, and the influence of parameters on the performance of the vortex tube has scarcely been by: 1.

The use of a vortex tube in hydrogen liquefaction has never been done before. The vortex tube is one of two distinguishing factors in our fueling station design. Conical vortex tubes are ultimately more efficient than a cylindrical vortex tube (Picture below).

Below is the estimated book value of our three vortex tube sub-system in ten. Turbulent Hydro. Unsubscribe from Turbulent Hydro. Subscribed Unsubscribe. Want to watch this again later. Sign in to add this video to a playlist. Need to report the video. Sign in to report. The method is demonstrated for a canonical Burgers vortex, a Bodewadt vortex, homogeneous isotropic turbulent flow, the wake of a propeller, a heaving plate, and a turning containership.

The proposed method helps to better visualize vortical flow fields by displaying vortex cores, complementing methods like Q and λ 2 which display vortical.

This paper presents a linearized theory for the average decay of a tape-induced fully developed turbulent swirl in flow through a pipe. In the Reynolds number range between 10 4 and 10 5 the theoretical analysis was found to be in good agreement with experimental data obtained with water in a 1 in.

pipe, provided the eddy diffusivity was chosen by: If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about sending content to Google Drive. The multi-mode stretched spiral vortex in homogeneous isotropic turbulenceCited by: complex flows like vortex.

Using commercial code CFX, Frohlingsdorf and Unger, [9] presented a numerical solution of flow and thermal separation occurring in the Ranque–Hilsch vortex tube.

The vortex flow in the vortex tube is of highly turbulent nature File Size: KB. • This animation shows a perspective view of time development of turbulent vortex structures extracted by the formula used in Ref.[1]. • Many turbulent vortex structures are generated in the.

Turbulent Shear Flows 7 Reconnection of Two Antiparallel Vortex Tubes: A New Cascade Mechanism. Pages Book Title Turbulent Shear Flows 7 Book Subtitle Selected Papers from the Seventh International Symposium on Turbulent Shear Flows, Stanford University, USA, August 21–23.

Study of the energy separation phenomenon in vortex tube (VT) at cryogenic temperature (temperature range below K) has become important because of the potential application of VT as in-flight air separator in air breathing propulsion.

In the present study, a CFD model is used to simulate the energy separation phenomenon in VT with gaseous air at cryogenic Cited by: 7.In near-wall flows (i.e., boundary layer, as well as tube and channel flows), turbulence generates in the region of the greatest near-wall velocity gradients throughout the flow extent.

However, the turbulent flow develops only on the upset of stability of a laminar flow existing at Reynolds numbers below a certain critical value Re c, which.Heat exchanger tubes can be damaged or fail if subjected to excessive flow-induced vibration, either from fatigue or fretting-wear.

Good heat exchanger design requires that the designer understands and accounts for the vibration mechanisms that might occur, such as vortex shedding, turbulent excitation or fluidelastic instability.