Acoustic measurement of oceanic turbulent kinetic energy dissipation rate, using a large‐eddy technique

2001 ◽  
Vol 110 (5) ◽  
pp. 2641-2641
Author(s):  
Ann E. Gargett
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Dissipation Rate ◽  
Energy Dissipation Rate ◽  
Acoustic Measurement ◽  
Large Eddy

scholarly journals Comment on “Using an ADCP to Estimate Turbulent Kinetic Energy Dissipation Rate in Sheltered Coastal Waters”

2017 ◽  
Vol 34 (6) ◽  
pp. 1387-1390 ◽  
Author(s):  
Ann E. Gargett
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Vertical Velocity ◽  
Dissipation Rate ◽  
Energy Dissipation Rate ◽  
Vertical Shear ◽  
Length Scale ◽  
Ocean Turbulence ◽  
Large Eddy

AbstractGreene et al. revisit the suggestion that the turbulent kinetic energy dissipation rate could be estimated through a “large-eddy estimate,” employing acoustic measurements of velocity fields associated with the largest energy-containing scales of ocean turbulence. While the large-eddy estimate as originally proposed used vertical velocity and a vertical eddy length scale, Greene et al. chose instead to substitute a horizontal length scale for the latter. This comment argues that combining a horizontal scale for length with a vertical velocity scale produces a large-eddy estimate of the dissipation rate that is accurate only if the energy-containing eddies are isotropic, and that this condition is highly unlikely in naturally occurring ocean turbulence, subject as it is to influences of stratification, vertical shear, and/or the presence of horizontal boundaries. The problem is documented using data from a large-eddy simulation of Langmuir supercells.

Evaluation of Turbulent Kinetic Energy Dissipation Rate in a Free Jet Flow from PIV Measurements

2012 ◽  
Vol 7 (1) ◽  
pp. 53-69
Author(s):  
Vladimir Dulin ◽  
Yuriy Kozorezov ◽  
Dmitriy Markovich
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Dissipation Rate ◽  
Energy Dissipation Rate ◽  
Turbulent Velocity ◽  
Small Scale ◽  
Velocity Fluctuations ◽  
Piv Measurements ◽  
Free Jet

The present paper reports PIV (Particle Image Velocimetry) measurements of turbulent velocity fluctuations statistics in development region of an axisymmetric free jet (Re = 28 000). To minimize measurement uncertainty, adaptive calibration, image processing and data post-processing algorithms were utilized. On the basis of theoretical analysis and direct measurements, the paper discusses effect of PIV spatial resolution on measured statistical characteristics of turbulent fluctuations. Underestimation of the second-order moments of velocity derivatives and of the turbulent kinetic energy dissipation rate due to a finite size of PIV interrogation area and finite thickness of laser sheet was analyzed from model spectra of turbulent velocity fluctuations. The results are in a good agreement with the measured experimental data. The paper also describes performance of possible ways to account for unresolved small-scale velocity fluctuations in PIV measurements of the dissipation rate. In particular, a turbulent viscosity model can be efficiently used to account for the unresolved pulsations in a free turbulent flow

scholarly journals Using an ADCP to Estimate Turbulent Kinetic Energy Dissipation Rate in Sheltered Coastal Waters

2015 ◽  
Vol 32 (2) ◽  
pp. 318-333 ◽  
Author(s):  
A. D. Greene ◽  
P. J. Hendricks ◽  
M. C. Gregg
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Cell Size ◽  
Dissipation Rate ◽  
Puget Sound ◽  
Acoustic Doppler Current Profiler ◽  
Energy Dissipation Rate ◽  
Integral Scale ◽  
Thorpe Scale

AbstractTurbulent microstructure and acoustic Doppler current profiler (ADCP) data were collected near Tacoma Narrows in Puget Sound, Washington. Over 100 coincident microstructure profiles have been compared to ADCP estimates of turbulent kinetic energy dissipation rate (ϵ). ADCP dissipation rates were calculated using the large-eddy method with theoretically determined corrections for sensor noise on rms velocity and integral-scale calculations. This work is an extension of Ann Gargett’s approach, which used a narrowband ADCP in regions with intense turbulence and strong vertical velocities. Here, a broadband ADCP is used to measure weaker turbulence and achieve greater horizontal and vertical resolution relative to the narrowband ADCP. Estimates of ϵ from the Modular Microstructure Profiler (MMP) and broadband ADCP show good quantitative agreement over nearly three decades of dissipation rate, 3 × 10−8–10−5 m2 s−3. This technique is most readily applied when the turbulent velocity is greater than the ADCP velocity uncertainty (σ) and the ADCP cell size is within a factor of 2 of the Thorpe scale. The 600-kHz broadband ADCP used in this experiment yielded a noise floor of 3 mm s−1 for 3-m vertical bins and 2-m along-track average (≈four pings), which resulted in turbulence levels measureable with the ADCP as weak as 3 × 10−8 m2 s−3. The value and trade-off of changing the ADCP cell size, which reduces noise but also changes the ratio of the Thorpe scale to the cell size, are discussed as well.

A CFD Methodology for Solid and Liquid Flow Fields of Sedimentation Tanks

2012 ◽  
Vol 178-181 ◽  
pp. 371-375
Author(s):  
Y. L. Liu ◽  
Y. Zheng ◽  
P. Zhang ◽  
W.L. Wei
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Dissipation Rate ◽  
Concentration Distribution ◽  
Energy Dissipation Rate ◽  
Two Phase ◽  
Sedimentation Tank ◽  
Solid Distribution ◽  
Solid Liquid

In this paper, the CFD approach is used to study the solid–liquid two-phase turbulent flow and sludge concentration distribution in a secondary sedimentation tank. By the simulation, the velocity and the turbulent kinetic energy and turbulent kinetic energy dissipation rate and solid distribution in a secondary sedimentation tank are obtained, which shows the simulation model is an effective method to investigate the flow patterns and their influence on the process inside the sedimentation vessel.

Sign in / Sign up

Export Citation Format

Share Document