TY - JOUR
T1 - Reynolds stress and turbulence estimates in bottom boundary layer of Fall of Warness
AU - Osalusi, Emmanuel
AU - Side, Jonathan Charles
AU - Harris, Robert Ewan
PY - 2009/5
Y1 - 2009/5
N2 - A broadband acoustic Doppler current profiler (ADCP) moored on the seabed at 42 m depth has been used to observe the mean and turbulent flow components in the tidally energetic Fall of Warness channel over two tidal cycles. The Reynolds stress has been estimated from the difference in variance between the along-beam velocities of opposing acoustic beams. Near bed stress at 2.63 m above seabed (mab) exceeds 7.5 Pa at the time of mean flow (speed of ~ 1.3 m s- 1) while the ebb stresses are limited to ~ 3.31 Pa during the peak ebb, mean, flow of ~ 1.3 m s- 1. The production of turbulent kinetic energy (TKE), P was found to be negative below 2 × 10- 9 W m- 3 and up to 6 × 10- 4 W m- 3 was estimated during flood flows and decreasing to 3 × 10- 4 W m- 3. The TKE dissipation rate e was estimated by inertial dissipation method (IDM) with the greatest value of 2.43 × 10- 2 W m- 3 observed near the seabed around maximum ebb, falling to 5.75 × 10- 5 W m- 3 around slack water. The comparison between P and e was performed by calculating individual ratios of P corresponding to e using a bootstrap resampling technique. The study shows that the ratio e/P averaged over whole flood and ebb were found to be ~ 0.4138 and ~ 0.4177, respectively, indicating that production exceeded dissipation. The uncertainties in Reynolds stress estimates due to instrument noise were found to be 3 × 10- 4 Pa while 4.52 × 10- 2 Pa can be attributed to the uncertainties due to the increase in the flow-related component. © 2009 Elsevier Ltd. All rights reserved.
AB - A broadband acoustic Doppler current profiler (ADCP) moored on the seabed at 42 m depth has been used to observe the mean and turbulent flow components in the tidally energetic Fall of Warness channel over two tidal cycles. The Reynolds stress has been estimated from the difference in variance between the along-beam velocities of opposing acoustic beams. Near bed stress at 2.63 m above seabed (mab) exceeds 7.5 Pa at the time of mean flow (speed of ~ 1.3 m s- 1) while the ebb stresses are limited to ~ 3.31 Pa during the peak ebb, mean, flow of ~ 1.3 m s- 1. The production of turbulent kinetic energy (TKE), P was found to be negative below 2 × 10- 9 W m- 3 and up to 6 × 10- 4 W m- 3 was estimated during flood flows and decreasing to 3 × 10- 4 W m- 3. The TKE dissipation rate e was estimated by inertial dissipation method (IDM) with the greatest value of 2.43 × 10- 2 W m- 3 observed near the seabed around maximum ebb, falling to 5.75 × 10- 5 W m- 3 around slack water. The comparison between P and e was performed by calculating individual ratios of P corresponding to e using a bootstrap resampling technique. The study shows that the ratio e/P averaged over whole flood and ebb were found to be ~ 0.4138 and ~ 0.4177, respectively, indicating that production exceeded dissipation. The uncertainties in Reynolds stress estimates due to instrument noise were found to be 3 × 10- 4 Pa while 4.52 × 10- 2 Pa can be attributed to the uncertainties due to the increase in the flow-related component. © 2009 Elsevier Ltd. All rights reserved.
KW - ADCP
KW - Reynolds stress
KW - TKE production
KW - Turbulent kinetic energy
UR - http://www.scopus.com/inward/record.url?scp=67349084597&partnerID=8YFLogxK
U2 - 10.1016/j.icheatmasstransfer.2009.02.004
DO - 10.1016/j.icheatmasstransfer.2009.02.004
M3 - Article
SN - 0735-1933
VL - 36
SP - 412
EP - 421
JO - International Communications in Heat and Mass Transfer
JF - International Communications in Heat and Mass Transfer
IS - 5
ER -