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.

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.

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.

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.

Three-dimensional conditional structure of a high-Reynolds-number turbulent boundary layer

2011 ◽  
Vol 673 ◽  
pp. 255-285 ◽  
Author(s):  
N. HUTCHINS ◽  
J. P. MONTY ◽  
B. GANAPATHISUBRAMANI ◽  
H. C. H. NG ◽  
I. MARUSIC
Keyword(s):  
Skin Friction ◽  
High Reynolds Number ◽  
Large Scale ◽  
Three Dimensional ◽  
Streamwise Velocity ◽  
Small Scale ◽  
Large Scale Structures ◽  
Local Mean ◽  
Scale Structures ◽  
High Reynolds

An array of surface hot-film shear-stress sensors together with a traversing hot-wire probe is used to identify the conditional structure associated with a large-scale skin-friction event in a high-Reynolds-number turbulent boundary layer. It is found that the large-scale skin-friction events convect at a velocity that is much faster than the local mean in the near-wall region (the convection velocity for large-scale skin-friction fluctuations is found to be close to the local mean at the midpoint of the logarithmic region). Instantaneous shear-stress data indicate the presence of large-scale structures at the wall that are comparable in scale and arrangement to the superstructure events that have been previously observed to populate the logarithmic regions of turbulent boundary layers. Conditional averages of streamwise velocity computed based on a low skin-friction footprint at the wall offer a wider three-dimensional view of the average superstructure event. These events consist of highly elongated forward-leaning low-speed structures, flanked on either side by high-speed events of similar general form. An analysis of small-scale energy associated with these large-scale events reveals that the small-scale velocity fluctuations are attenuated near the wall and upstream of a low skin-friction event, while downstream and above the low skin-friction event, the fluctuations are significantly amplified. In general, it is observed that the attenuation and amplification of the small-scale energy seems to approximately align with large-scale regions of streamwise acceleration and deceleration, respectively. Further conditional averaging based on streamwise skin-friction gradients confirms this observation. A conditioning scheme to detect the presence of meandering large-scale structures is also proposed. The large-scale meandering events are shown to be a possible source of the strong streamwise velocity gradients, and as such play a significant role in modulating the small-scale motions.

Pipe Flow Measurements of a Transparent Non-Newtonian Slurry

1989 ◽  
Vol 111 (3) ◽  
pp. 331-336 ◽  
Author(s):  
J. T. Park ◽  
R. J. Mannheimer ◽  
T. A. Grimley ◽  
T. B. Morrow
Keyword(s):  
Velocity Profile ◽  
Newtonian Fluid ◽  
Power Law ◽  
Pipe Flow ◽  
Large Scale ◽  
Longitudinal Velocity ◽  
Tangential Velocity ◽  
Turbulent Pipe Flow ◽  
Laser Doppler Velocimeter ◽  
Flow Measurements

An experimental description of the flow structure of non-Newtonian slurries in the laminar, transitional, and full turbulent pipe flow regimes is the primary objective of this research. Experiments were conducted in a large-scale pipe slurry flow facility with an inside pipe diameter of 51 mm. The transparent slurry formulated for these experiments from silica, mineral oil, and Stoddard solvent exhibited a yield-power-law behavior from concentric-cylinder viscometer measurements. The velocity profile for laminar flow from laser Doppler velocimeter (LDV) measurements had a central plug flow region, and it was in agreement with theory. The range of the transition region was narrower than that for a Newtonian fluid. The mean velocity profile for turbulent flow was close to a 1/7 power-law velocity profile. The rms longitudinal velocity profile was also similar to a classical turbulent pipe flow experiment for a Newtonian fluid; however, the rms tangential velocity profile was significantly different.

scholarly journals The evolution of large-scale motions in turbulent pipe flow

2015 ◽  
Vol 779 ◽  
pp. 701-715 ◽  
Author(s):  
Leo H. O. Hellström ◽  
Bharathram Ganapathisubramani ◽  
Alexander J. Smits
Keyword(s):  
Pipe Flow ◽  
Large Scale ◽  
Complex Structure ◽  
Turbulent Pipe Flow ◽  
Large Scale Structures ◽  
Large Structures ◽  
Scale Structures ◽  
The Cross ◽  
Spatio Temporal ◽  
Temporal Extent

A dual-plane snapshot proper orthogonal decomposition (POD) analysis of turbulent pipe flow at a Reynolds number of 104 000 is presented. The high-speed particle image velocimetry data were simultaneously acquired in two planes, a cross-stream plane (2D–3C) and a streamwise plane (2D–2C) on the pipe centreline. The cross-stream plane analysis revealed large structures with a spatio-temporal extent of $1{-}2R$, where $R$ is the pipe radius. The temporal evolution of these large-scale structures is examined using the time-shifted correlation of the cross-stream snapshot POD coefficients, identifying the low-energy intermediate modes responsible for the transition between the large-scale modes. By conditionally averaging based on the occurrence/intensity of a given cross-stream snapshot POD mode, a complex structure consisting of wall-attached and -detached large-scale structures is shown to be associated with the most energetic modes. There is a pseudo-alignment of these large structures, which together create structures with a spatio-temporal extent of approximately $6R$, which appears to explain the formation of the very-large-scale motions previously observed in pipe flow.

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