Vertical Round Buoyant Jets and Fountains in a Linearly, Density-Stratified Fluid

• Published in: Fluids (Basel) Vol. 5; no. 4; p. 232
• Main Authors: Papanicolaou, Panos N., Stamoulis, George C.
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.12.2020
• Subjects: Asymptotic properties; Atmosphere; Buoyancy; buoyant jet; Buoyant jets; Computational fluid dynamics; Density; Dimensional analysis; Elevation; Entrainment; Experiments; Fluid flow; fountain; Fountains; Jets; Kinematics; linear density gradient; Momentum; negative buoyancy; Plumes; stratified ambient; terminal height of rise
• ISSN: 2311-5521; 2311-5521
• DOI: 10.3390/fluids5040232

Turbulent round buoyant jets and fountains issuing vertically into a linearly density-stratified calm ambient have been investigated in a series of laboratory experiments. The terminal (steady-state) height of rise and the mean elevation of subsequent horizontal spreading have been measured in positively buoyant jets (at source level), including pure momentum jets and plumes, as well in momentum-driven negatively buoyant jets (fountains). The results from experiments confirmed the asymptotic analysis that was based on dimensional arguments. The normalized terminal height and spreading elevation with respect to the elevation of injection of momentum-driven (positively) buoyant jets and fountains attained the same asymptotic values. The numerical results from the solution of entrainment equations, using an improved entrainment coefficient function, confirmed the results related to buoyancy dominant flows (plumes), while their predictions in momentum-driven flows were quite low if compared to measurements.