Scaling for turbulent viscosity of buoyant plumes in stratified fluids : PIV measurement with implications for submarine hydrothermal plume turbulence
MetadataShow full item record
KeywordHydrothermal plume turbulence; ‘Plume-cap’ entrainment; Turbulent viscosity; Time-resolved particle image velocimetry
Time-resolved particle image velocimetry (PIV) has been used to measure instantaneous twodimensional velocity vector fields of laboratory-generated turbulent buoyant plumes in linearly stratified saltwater over extended periods of time. From PIV-measured time-series flow data, characteristics of plume mean flow and turbulence have been quantified. To be specific, maximum plume penetration scaling and entrainment coefficient determined from the mean flow agree well with the theory based on the entrainment hypothesis for buoyant plumes in stratified fluids. Besides the well-known persistent entrainment along the plume stem (i.e., the ‘plumestem’ entrainment), the mean plume velocity field shows persistent entrainment along the outer edge of the plume cap (i.e., the ‘plume-cap’ entrainment), thereby confirming predictions from previous numerical simulation studies. To our knowledge, the present PIV investigation provides the first measured flow field data in the plume cap region. As to measured plume turbulence, both the turbulent kinetic energy field and the turbulence dissipation rate field attain their maximum close to the source, while the turbulent viscosity field reaches its maximum within the plume cap region; the results also show that maximum turbulent viscosity scales as νt,max = 0.030 (B/N)1/2, where B is source buoyancy flux and N is ambient buoyancy frequency. These PIV data combined with previously published numerical simulation results have implications for understanding the roles of hydrothermal plume turbulence, i.e. plume turbulence within the cap region causes the ‘plume-cap’ entrainment that plays an equally important role as the ‘plume-stem’ entrainment in supplying the final volume flux at the plume spreading level.
© The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 129 (2017): 89-98, doi:10.1016/j.dsr.2017.10.006.
Suggested CitationPreprint: Zhang, Wei, He, Zhiguo, Jiang, Houshuo, "Scaling for turbulent viscosity of buoyant plumes in stratified fluids : PIV measurement with implications for submarine hydrothermal plume turbulence", 2017-10-07, https://doi.org/10.1016/j.dsr.2017.10.006, https://hdl.handle.net/1912/9422
Showing items related by title, author, creator and subject.
The relative effect of particles and turbulence on acoustic scattering from deep sea hydrothermal vent plumes revisited Xu, Guangyu; Jackson, Darrell R.; Bemis, Karen G. (Acoustical Society of America, 2017-03-03)The relative importance of suspended particles and turbulence as backscattering mechanisms within a hydrothermal plume located on the Endeavour Segment of the Juan de Fuca Ridge is determined by comparing acoustic backscatter ...
Cenedese, Claudia; Linden, P. F. (Cambridge University Press, 2014-07-11)A model of the total volume flux and entrainment occurring in two coalescing axisymmetric turbulent plumes is developed and compared with laboratory experiments. The dynamical evolution of the two plumes is divided into ...
Dynamics of a turbulent buoyant plume in a stratified fluid : an idealized model of subglacial discharge in Greenland fjords Ezhova, Ekaterina; Cenedese, Claudia; Brandt, Luca (American Meteorological Society, 2017-10-26)This study reports the results of large-eddy simulations of an axisymmetric turbulent buoyant plume in a stratified fluid. The configuration used is an idealized model of the plume generated by a subglacial discharge at ...