Wall Pressure in Developing Turbulent Pipe Flows

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Kamal Selvam ◽  
Emir Öngüner ◽  
Jorge Peixinho ◽  
El-Sayed Zanoun ◽  
Christoph Egbers
Keyword(s):  
Turbulent Flows ◽  
Exponential Growth ◽  
Pressure Fluctuations ◽  
Axial Direction ◽  
Wall Pressure ◽  
Mean Velocity ◽  
Critical Position ◽  
Velocity Fluctuations ◽  
Developed Turbulence ◽  
Layer Flow

Velocity fluctuations are widely used to identify the behavior of developing turbulent flows. The pressure on the other hand, which is strongly coupled with the gradient of the mean velocity and fluctuations, is less explored. In this study, we report the results of wall pressure measurements for the development of pipe flow at high Reynolds numbers along the axial direction. It is found that the pressure fluctuations increase exponentially along the pipe with a self-similarity scaling. The exponential growth of the pressure fluctuations along the pipe saturates after reaching a critical position around 50 diameters from the inlet. It qualitatively agrees with the critical position usually adopted for fully developed turbulence, which was obtained from earlier velocity fluctuations at various locations along the pipe centerline. Results also show that the exponential growth of the pressure fluctuations is weakly affected by the presence of ring obstacles placed close to the pipe inlet. Finally, it is found that the pressure fluctuations decrease as a function of Reynolds number, contrary to the boundary layer flow.

scholarly journals Natural logarithms

2013 ◽  
Vol 718 ◽  
pp. 1-4 ◽  
Author(s):  
B. J. McKeon
Keyword(s):  
Turbulent Flows ◽  
Reynolds Numbers ◽  
Streamwise Velocity ◽  
Wall Turbulence ◽  
Significant Advance ◽  
Mean Velocity ◽  
Velocity Fluctuations ◽  
Logarithmic Scaling ◽  
The Mean ◽  
High Reynolds

AbstractMarusic et al. (J. Fluid Mech., vol. 716, 2013, R3) show the first clear evidence of universal logarithmic scaling emerging naturally (and simultaneously) in the mean velocity and the intensity of the streamwise velocity fluctuations about that mean in canonical turbulent flows near walls. These observations represent a significant advance in understanding of the behaviour of wall turbulence at high Reynolds number, but perhaps the most exciting implication of the experimental results lies in the agreement with the predictions of such scaling from a model introduced by Townsend (J. Fluid Mech., vol. 11, 1961, pp. 97–120), commonly termed the attached eddy hypothesis. The elegantly simple, yet powerful, study by Marusic et al. should spark further investigation of the behaviour of all fluctuating velocity components at high Reynolds numbers and the outstanding predictions of the attached eddy hypothesis.

The scaling of the wall pressure fluctuations in polymer-modified turbulent boundary layer flow

2000 ◽  
Vol 108 (1) ◽  
pp. 71-75 ◽  
Author(s):  
Timothy A. Brungart ◽  
Wayne J. Holmberg ◽  
Arnold A. Fontaine ◽  
Steven Deutsch ◽  
Howard L. Petrie
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Boundary Layer Flow ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Wall Pressure Fluctuations ◽  
Turbulent Boundary Layer Flow ◽  
Layer Flow

Wall pressure fluctuations in attached boundary-layer flow

AIAA Journal ◽  
1983 ◽  
Vol 21 (4) ◽  
pp. 495-502 ◽  
Author(s):  
A. L. Laganelli ◽  
A. Martellucci ◽  
L. L. Shaw
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Wall Pressure Fluctuations ◽  
Layer Flow

Acoustic Radiation From Separated Boundary-Layer Flow Over a Rearward-Facing Step on a Flat Panel

2003 ◽  
Author(s):  
Walter A. Kargus ◽  
Gerald C. Lauchle
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Acoustic Radiation ◽  
Fluid Dynamic ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Wall Jet ◽  
Measured Velocity ◽  
Wall Pressure Fluctuations ◽  
Layer Flow

The acoustic radiation from a turbulent boundary layer that occurs downstream of a rearward facing step discontinuity and reattaches to a flat plat is considred experimentally. The step is exposed ot a zero incidence, uniform subsonic flow. a quiet wall jet facility situated in an anechoic chamber is used for the studies. The “point” wall pressure spectra are measured by small, “pinhole” microphones located at various locations under the layer, including a point directly in the 90° corner of the step. The wall pressure fluctuations measured at the various locations are correlated with the signal detected by a far-field microphone. The measured cross-spectral densities are thus used to identify the relative contributions of the various flow regimes to the direct radiation. It is shown that the separation of the flow over the corner of the step is a dominant acoustic source, which is supported not only by the measured cross spectra, but also by the favorable comparison of the measured velocity power law to the theoretical value. Measurements made where the flow reattaches and at the turbulent boundary layer are less conclusive. This is because the pinhole tube attached to the microphone produced a sound due to a fluid-dynamic oscillation, which contaminated the measurement of the aeroacoustic sources.

An Investigation of two Turbulent Flows over Smooth and Rough Surfaces

1974 ◽  
Vol 16 (2) ◽  
pp. 71-78 ◽  
Author(s):  
W. K. Allan ◽  
V. Sharma
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Surface Roughness ◽  
Turbulent Boundary Layer ◽  
Turbulent Flows ◽  
Smooth Surface ◽  
Two Dimensional ◽  
Mean Velocity ◽  
Turbulent Boundary Layer Flow ◽  
Layer Flow

Experimental data for two-dimensional, low-speed, turbulent boundary layer flow has been used to verify the description of mean-velocity distributions proposed by Allan and to re-evaluate the entrainment function. The independence of pressure gradient and surface roughness as regards their effects on velocity profiles has been demonstrated. Boundary layer predictions agree with experimental data for a smooth surface, but further investigation is required for flow over a rough surface.

scholarly journals Turbulent boundary layers and channels at moderate Reynolds numbers

2010 ◽  
Vol 657 ◽  
pp. 335-360 ◽  
Author(s):  
JAVIER JIMÉNEZ ◽  
SERGIO HOYAS ◽  
MARK P. SIMENS ◽  
YOSHINORI MIZUNO
Keyword(s):  
Boundary Layer ◽  
Boundary Layers ◽  
Turbulent Flows ◽  
Pressure Fluctuations ◽  
Reynolds Numbers ◽  
Streamwise Velocity ◽  
Rotational Flow ◽  
Mean Velocity ◽  
The Mean ◽  
External Flows

The behaviour of the velocity and pressure fluctuations in the outer layers of wall-bounded turbulent flows is analysed by comparing a new simulation of the zero-pressure-gradient boundary layer with older simulations of channels. The 99 % boundary-layer thickness is used as a reasonable analogue of the channel half-width, but the two flows are found to be too different for the analogy to be complete. In agreement with previous results, it is found that the fluctuations of the transverse velocities and of the pressure are stronger in the boundary layer, and this is traced to the pressure fluctuations induced in the outer intermittent layer by the differences between the potential and rotational flow regions. The same effect is also shown to be responsible for the stronger wake component of the mean velocity profile in external flows, whose increased energy production is the ultimate reason for the stronger fluctuations. Contrary to some previous results by our group, and by others, the streamwise velocity fluctuations are also found to be higher in boundary layers, although the effect is weaker. Within the limitations of the non-parallel nature of the boundary layer, the wall-parallel scales of all the fluctuations are similar in both the flows, suggesting that the scale-selection mechanism resides just below the intermittent region, y/δ = 0.3–0.5. This is also the location of the largest differences in the intensities, although the limited Reynolds number of the boundary-layer simulation (Reθ ≈ 2000) prevents firm conclusions on the scaling of this location. The statistics of the new boundary layer are available from http://torroja.dmt.upm.es/ftp/blayers/.

scholarly journals ANALYSIS OF ENERGY SPECTRA BY THE VORTEX METHOD WITH ARTIFICIAL TURBULENCE

2004 ◽  
Vol 3 (2) ◽  
pp. 143
Author(s):  
Y. Ogami ◽  
K. Nishiwaki ◽  
Y. Yoshihara
Keyword(s):  
Turbulent Flows ◽  
Kinematic Viscosity ◽  
Vortex Method ◽  
Energy Spectra ◽  
Mean Square ◽  
Characteristic Parameters ◽  
Mean Velocity ◽  
Velocity Fluctuations ◽  
Inlet Condition ◽  
The Given

First, in order to use as an inlet condition for turbulent simulation, a method is presented which produces numerically an artificial turbulence, namely, a series of velocity fluctuations of which frequency is Gaussian, and energy spectrum and root mean square correspond to the given ones. Besides, the fluctuation data are determined by the characteristic parameters of turbulent flows such as the inlet mean velocity, the kinematic viscosity, the Kolmogorov scale and the integral time scale. Our examples show excellent accuracy and flexibility of the method. Secondly, the vortex method has been studied to see the ability of the method to deal with turbulent flows. It is found that the energy spectra produced by this agree well with the ones given as the inlet condition, and that the vortex method is able to produce turbulent flows with the given parameters described above.

Sign in / Sign up

Export Citation Format

Share Document