TY - JOUR
T1 - Turbulent kinetic energy redistribution in a gravity current interacting with an emergent cylinder
AU - Di Lollo, Giovanni
AU - Adduce, Claudia
AU - Brito, Moisés
AU - Ferreira, Rui M. L.
AU - Ricardo, Ana M.
N1 - Funding Information:
AR and RF acknowledge the Portuguese Foundation for Science and Technology (FCT) for its financial support via the project PTDC/CTA-OHR/30561/2017 (WinTherface). MB acknowledges the Portuguese Foundation for Science and Technology (FCT-MCTES) for its financial support via the project UIDB/00667/2020 and UIDP/00667/2020 (UNIDEMI). CA acknowledges the Italian Ministry of University and Research (MUR) for funding the project 2022SAFKS4 . All Authors have read and approved the submitted manuscript.
Publisher Copyright:
© 2023 The Authors
PY - 2024/1
Y1 - 2024/1
N2 - Gravity currents are flows driven by density gradients between two or more contacting fluids and play a key role in nature and industrial environments via global ocean circulations, climate variability and the distribution of airborne pollutants. In the present work, we study, experimentally, the changes induced by an emergent vertical PVC cylinder on the mean and turbulent flow fields of an unsteady bottom-generated lock release gravity current. Tests were carried out, with and without the cylinder, in refractive index matching conditions and instantaneous velocities were acquired with a Particle Image Velocimetry system. The mean velocity field, Reynolds stresses and terms of turbulent kinetic energy (TKE) budget for the currents head were presented and discussed. The results show that the adverse pressure gradient generated by the cylinder induces a uniform deceleration of the current head. Hence, there are no appreciable differences on the spatial distribution of the mean velocities in the current head, compared to the undisturbed current. On the other hand, the changes on the turbulent flow field are remarkable. The total diffusion of TKE decays in the inner part of the head while becoming stronger at the interface between the two fluids, as the current approaches the cylinder. This is associated to an increase of the diffusion term due to pressure fluctuations, that acts against diffusion due to velocity fluctuations and contributes to disrupt the transport of TKE from the interface between the fluids and the inner part of the current. As a result, in the presence of an obstacle, Reynolds stresses are suppressed in the inner part of the current head and enhanced at the interface.
AB - Gravity currents are flows driven by density gradients between two or more contacting fluids and play a key role in nature and industrial environments via global ocean circulations, climate variability and the distribution of airborne pollutants. In the present work, we study, experimentally, the changes induced by an emergent vertical PVC cylinder on the mean and turbulent flow fields of an unsteady bottom-generated lock release gravity current. Tests were carried out, with and without the cylinder, in refractive index matching conditions and instantaneous velocities were acquired with a Particle Image Velocimetry system. The mean velocity field, Reynolds stresses and terms of turbulent kinetic energy (TKE) budget for the currents head were presented and discussed. The results show that the adverse pressure gradient generated by the cylinder induces a uniform deceleration of the current head. Hence, there are no appreciable differences on the spatial distribution of the mean velocities in the current head, compared to the undisturbed current. On the other hand, the changes on the turbulent flow field are remarkable. The total diffusion of TKE decays in the inner part of the head while becoming stronger at the interface between the two fluids, as the current approaches the cylinder. This is associated to an increase of the diffusion term due to pressure fluctuations, that acts against diffusion due to velocity fluctuations and contributes to disrupt the transport of TKE from the interface between the fluids and the inner part of the current. As a result, in the presence of an obstacle, Reynolds stresses are suppressed in the inner part of the current head and enhanced at the interface.
KW - Emergent obstacle
KW - Gravity currents
KW - Lock release
KW - PIV
KW - Pressure diffusion
KW - Turbulence kinetic energy
UR - http://www.scopus.com/inward/record.url?scp=85179882690&partnerID=8YFLogxK
U2 - 10.1016/j.advwatres.2023.104585
DO - 10.1016/j.advwatres.2023.104585
M3 - Article
AN - SCOPUS:85179882690
SN - 0309-1708
VL - 183
JO - Advances In Water Resources
JF - Advances In Water Resources
M1 - 104585
ER -