Structural organization of large and very large scales in turbulent pipe flow simulation

2013 ◽  
Vol 720 ◽  
pp. 236-279 ◽  
Author(s):  
J. R. Baltzer ◽  
R. J. Adrian ◽  
Xiaohua Wu
Keyword(s):  
Turbulent Flows ◽  
Pipe Flow ◽  
Velocity Fluctuation ◽  
Large Scale ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Streamwise Velocity ◽  
Turbulent Pipe Flow ◽  
Low Velocity ◽  
Logarithmic Layer

AbstractThe physical structures of velocity are examined from a recent direct numerical simulation of fully developed incompressible turbulent pipe flow (Wu, Baltzer & Adrian, J. Fluid Mech., vol. 698, 2012, pp. 235–281) at a Reynolds number of ${\mathit{Re}}_{D} = 24\hspace{0.167em} 580$ (based on bulk velocity) and a Kármán number of ${R}^{+ } = 685$. In that work, the periodic domain length of $30$ pipe radii $R$ was found to be sufficient to examine long motions of negative streamwise velocity fluctuation that are commonly observed in wall-bounded turbulent flows and correspond to the large fractions of energy present at very long streamwise wavelengths (${\geq }3R$). In this paper we study how long motions are composed of smaller motions. We characterize the spatial arrangements of very large-scale motions (VLSMs) extending through the logarithmic layer and above, and we find that they possess dominant helix angles (azimuthal inclinations relative to streamwise) that are revealed by two- and three-dimensional two-point spatial correlations of velocity. The correlations also reveal that the shorter, large-scale motions (LSMs) that concatenate to comprise the VLSMs are themselves more streamwise aligned. We show that the largest VLSMs possess a form similar to roll cells centred above the logarithmic layer and that they appear to play an important role in organizing the flow, while themselves contributing only a minor fraction of the flow turbulent kinetic energy. The roll cell motions play an important role with the smaller scales of motion that are necessary to create the strong streamwise streaks of low-velocity fluctuation that characterize the flow.

Azimuthal structure of turbulence in high Reynolds number pipe flow

2008 ◽  
Vol 615 ◽  
pp. 121-138 ◽  
Author(s):  
SEAN C. C. BAILEY ◽  
MARCUS HULTMARK ◽  
ALEXANDER J. SMITS ◽  
MICHAEL P. SCHULTZ
Keyword(s):  
Reynolds Number ◽  
Pipe Flow ◽  
Large Scale ◽  
Streamwise Velocity ◽  
Turbulent Pipe Flow ◽  
Roughness Effects ◽  
Azimuthal Correlations ◽  
Normal Distance ◽  
Logarithmic Layer ◽  
High Reynolds

Two-point hot-wire measurements of streamwise velocity were performed in the logarithmic and wake regions of turbulent pipe flow for Reynolds numbers, based on pipe diameter, ranging from 7.6 × 104 to 8.3 × 106 at four wall-normal positions with azimuthal probe separation. The azimuthal correlations were found to be consistent with the presence of very large-scale coherent regions of low-wavenumber, low-momentum fluid observed in previous studies of wall-bounded flows and were found to be independent of changing Reynolds number and surface roughness effects. At the edge of the logarithmic layer the azimuthal scale determined from the correlations was found to be similar to that observed for channel flows but larger than that observed for boundary layers, inconsistent with the concept of a universal logarithmic region. As the wall-normal position increased outside the logarithmic layer, there was a decrease in azimuthal scale relative to that of channel flow. Using cross-spectral analysis, high-wavenumber motion was found to grow azimuthally with wall-normal distance at a faster rate than the low-wavenumber motions.

Space–time formation of very-large-scale motions in turbulent pipe flow

2019 ◽  
Vol 881 ◽  
pp. 1010-1047 ◽  
Author(s):  
Jae Hwa Lee ◽  
Hyung Jin Sung ◽  
Ronald J. Adrian
Keyword(s):  
Pipe Flow ◽  
Large Scale ◽  
Spatial Organization ◽  
Three Dimensional ◽  
Streamwise Velocity ◽  
Turbulent Pipe Flow ◽  
Strain Component ◽  
Spatial Correlations ◽  
Correlation Pattern ◽  
Using Data

We examine the origin of very-large-scale motions (VLSMs) in fully developed turbulent pipe flow at friction Reynolds number, $\mathit{Re}_{\unicode[STIX]{x1D70F}}=934$, using data from a direct numerical simulation. The VLSMs and the packet-like large-scale motions (LSMs) found in this study are very similar to those found in earlier studies. Three-dimensional time-evolving instantaneous fields show that one component of the process leading to the large streamwise length of VLSMs is the concatenation of adjacent streamwise LSMs caused by the continuous elongation of LSMs due to the strain component of the mean shear. Spatial organization patterns of the VLSMs and LSMs and their properties are studied by separating auto-correlation of the streamwise velocity fluctuations into the components of the VLSM and the LSM defined by low-pass/high-pass filtering in the streamwise direction. The structures of the two-point spatial correlations of the streamwise velocity component of the VLSMs and the LSMs in the streamwise-azimuthal plane are characterized by multiple maxima and complex patterns that beg explanation in terms of patterned coherent arrangements of the LSMs. Using proper orthogonal decomposition (POD), it is found that the X-shape correlation pattern of the VLSMs results from the superposition of very long helically inclined structures and streamwise-aligned structures. Further explanation of the patterns in the correlations of the VLSMs and LSMs is provided through the study of synthetically constructed arrangements of simple hairpin packet models of the LSM. Head-to-tail alignment of the model packets along streamwise and helical directions suggested by the eigenvalues of the POD creates a pair of long roll-cells centred above the logarithmic layer, and bracketing the LSMs. These roll-cells are pure kinematic consequences of the induction within the LSM packets, but they may also serve to organize smaller packets.

Self-similarity of the large-scale motions in turbulent pipe flow

2016 ◽  
Vol 792 ◽  
Author(s):  
Leo H. O. Hellström ◽  
Ivan Marusic ◽  
Alexander J. Smits
Keyword(s):  
Turbulent Flows ◽  
Pipe Flow ◽  
Large Scale ◽  
Decomposition Analysis ◽  
Turbulent Pipe Flow ◽  
Self Similarity ◽  
Cross Sectional ◽  
Self Similar ◽  
Logarithmic Layer ◽  
Sectional Shape

Townsend’s attached eddy hypothesis assumes the existence of a set of energetic and geometrically self-similar eddies in the logarithmic layer in wall-bounded turbulent flows, which can be scaled with their distance to the wall. To examine the possible self-similarity of the energetic eddies in fully developed turbulent pipe flow, we performed stereo particle image velocimetry measurements together with a proper orthogonal decomposition analysis. For two Reynolds numbers, $Re_{{\it\tau}}=1330$ and 2460, the resulting modes/eddies were shown to exhibit self-similar behaviour for eddies with wall-normal length scales spanning a decade. This single length scale provides a complete description of the cross-sectional shape of the self-similar eddies.

Experimental investigation of the structure of large- and very-large-scale motions in turbulent pipe flow

2010 ◽  
Vol 651 ◽  
pp. 339-356 ◽  
Author(s):  
SEAN C. C. BAILEY ◽  
ALEXANDER J. SMITS
Keyword(s):  
Outer Layer ◽  
Pipe Flow ◽  
Large Scale ◽  
Decomposition Analysis ◽  
Turbulent Pipe Flow ◽  
Azimuthal Mode ◽  
Wide Range ◽  
Point Velocity ◽  
Logarithmic Layer ◽  
Proper Orthogonal

Multi-point velocity measurements have been performed in turbulent pipe flow at ReD = 1.5 × 105 and combined with cross-spectral and proper orthogonal decomposition analysis to elucidate information on the structure of the large- and very-large-scale motions in the outer layer of wall-bounded flows. The results indicate that in the outer layer the large-scale motions (LSM) may be composed of detached eddies with a wide range of azimuthal scales, whereas in the logarithmic layer they are attached. The very-large-scale motions (VLSM) have large radial scales, are concentrated around a single azimuthal mode and make a smaller angle with the wall compared to the LSM. The results support a hypothesis that only the detached LSM in the outer layer align to form the VLSM.

scholarly journals Secondary motion in turbulent pipe flow with three-dimensional roughness

2018 ◽  
Vol 854 ◽  
pp. 5-33 ◽  
Author(s):  
L. Chan ◽  
M. MacDonald ◽  
D. Chung ◽  
N. Hutchins ◽  
A. Ooi
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Streamwise Velocity ◽  
Secondary Flows ◽  
Turbulent Pipe Flow ◽  
Roughness Height ◽  
Stress Profile ◽  
Roughness Elements ◽  
Secondary Motion ◽  
Proportional Increase

The occurrence of secondary flows is investigated for three-dimensional sinusoidal roughness where the wavelength and height of the roughness elements are systematically altered. The flow spanned from the transitionally rough regime up to the fully rough regime and the solidity of the roughness ranged from a wavy, sparse roughness to a dense roughness. Analysing the time-averaged velocity, secondary flows are observed in all of the cases, reflected in the coherent stress profile which is dominant in the vicinity of the roughness elements. The roughness sublayer, defined as the region where the coherent stress is non-zero, scales with the roughness wavelength when the roughness is geometrically scaled (proportional increase in both roughness height and wavelength) and when the wavelength increases at fixed roughness height. Premultiplied energy spectra of the streamwise velocity turbulent fluctuations show that energy is reorganised from the largest streamwise wavelengths to the shorter streamwise wavelengths. The peaks in the premultiplied spectra at the streamwise and spanwise wavelengths are correlated with the roughness wavelength in the fully rough regime. Current simulations show that the spanwise scale of roughness determines the occurrence of large-scale secondary flows.

Characterization of Geometrical and Temporal Properties of Large-scale Motions in Turbulent Flows

2021 ◽  
Author(s):  
Christina Tsai ◽  
Kuang-Ting Wu
Keyword(s):  
Turbulent Flow ◽  
Turbulent Flows ◽  
Coherent Structures ◽  
Large Scale ◽  
Streamwise Velocity ◽  
Turbulent Structures ◽  
Temporal Properties ◽  
Turbulent Statistics ◽  
Spatial Locations

<p>It is demonstrated that turbulent boundary layers are populated by a hierarchy of recurrent structures, normally referred to as the coherent structures. Thus, it is desirable to gain a better understanding of the spatial-temporal characteristics of coherent structures and their impact on fluid particles. Furthermore, the ejection and sweep events play an important role in turbulent statistics. Therefore, this study focuses on the characterizations of flow particles under the influence of the above-mentioned two structures.</p><div><span>With regard to the geometry of turbulent structures, </span><span>Meinhart & Adrian (1995) </span>first highlighted the existence of large and irregularly shaped regions of uniform streamwise momentum zone (hereafter referred to as a uniform momentum zone, or UMZs), regions of relatively similar streamwise velocity with coherence in the streamwise and wall-normal directions.  <span>Subsequently, </span><span>de Silva et al. (2017) </span><span>provided a detection criterion that had previously been utilized to locate the uniform momentum zones (UMZ) and demonstrated the application of this criterion to estimate the spatial locations of the edges that demarcates UMZs.</span></div><div> </div><div>In this study, detection of the existence of UMZs is a pre-process of identifying the coherent structures. After the edges of UMZs are determined, the identification procedure of ejection and sweep events from turbulent flow DNS data should be defined. As such, an integrated criterion of distinguishing ejection and sweep events is proposed. Based on the integrated criterion, the statistical characterizations of coherent structures from available turbulent flow data such as event durations, event maximum heights, and wall-normal and streamwise lengths can be presented.</div>

scholarly journals P-wave crustal tomography of Greece with use of an accurate two-point ray tracer

1997 ◽  
Vol 40 (1) ◽  
Author(s):  
G. Drakatos ◽  
G. Karantonis ◽  
G. N. Stavrakakis
Keyword(s):  
Large Scale ◽  
Velocity Structure ◽  
Three Dimensional ◽  
Seismic Energy ◽  
Aegean Sea ◽  
P Wave ◽  
Low Velocity ◽  
Aegean Area ◽  
Arrival Times ◽  
Horizontal Variations

The three-dimensional velocity structure of the crust in the Aegean sea and the surrounding regions (34.0º-42.OºN, 19.0ºE-29.0ºE) is investigated by inversion of about 10000 residuals of arrival times of P-wave from local events. The resulting velocity structure shows strong horizontal variations due to the complicated crustal structure and the variations of crustal thickness. The northern part of the region generally shows high velocities. In the inner part of the volcanic arc (Southern Aegean area), relatively low velocities are observed, suggesting a large-scale absorption of seismic energy as confirmed by the low seismicity of the region. A low velocity zone was observed along the subduction zone of the region, up to a depth of 4 km. The existence of such a zone could be due to granitic or other intrusions in the crust during the uplift of the region during Alpidic orogenesis.

Fluid Transmission Line Modeling Using a Variational Method

1998 ◽  
Vol 122 (1) ◽  
pp. 153-162 ◽  
Author(s):  
Jari Ma¨kinen ◽  
Robert Piche´ ◽  
Asko Ellman
Keyword(s):  
Differential Equations ◽  
Variational Method ◽  
Ordinary Differential Equations ◽  
Transmission Lines ◽  
Pipe Flow ◽  
Transient Flow ◽  
Numerical Models ◽  
Flow Simulation ◽  
Gibbs Phenomenon ◽  
Turbulent Pipe Flow

A variational method is used to derive numerical models for transient flow simulation in fluid transmission lines. These are generalizations of models derived using the more traditional modal method. Three different transient compressible laminar pipe flow models are considered (inviscous, one-dimensional linear viscous, and two-dimensional dissipative viscous flow), and a model for transient turbulent pipe flow is given. The (model) equations in the laminar case are given in the form of a set of constant coefficient ordinary differential equations, and for the turbulent case (model) in the form of a set of nonlinear ordinary differential equations. Explicit equations are given for various end conditions. Attenuation factors, similar to the window functions used in spectral analysis, are used to attenuate Gibbs phenomenon oscillations. [S0022-0434(00)03201-9]

Asymptotic scaling in turbulent pipe flow

2007 ◽  
Vol 365 (1852) ◽  
pp. 771-787 ◽  
Author(s):  
B.J McKeon ◽  
J.F Morrison
Keyword(s):  
Asymptotic Behaviour ◽  
Pipe Flow ◽  
Physical Space ◽  
Reynolds Numbers ◽  
Streamwise Velocity ◽  
Turbulent Pipe Flow ◽  
Inertial Subrange ◽  
Velocity Spectrum ◽  
Mean Velocity ◽  
High Reynolds

The streamwise velocity component in turbulent pipe flow is assessed to determine whether it exhibits asymptotic behaviour that is indicative of high Reynolds numbers. The asymptotic behaviour of both the mean velocity (in the form of the log law) and that of the second moment of the streamwise component of velocity in the outer and overlap regions is consistent with the development of spectral regions which indicate inertial scaling. It is shown that an ‘inertial sublayer’ in physical space may be considered as a spatial analogue of the inertial subrange in the velocity spectrum and such behaviour only appears for Reynolds numbers R + >5×10 3 , approximately, much higher than was generally thought.

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