scholarly journals Flow behaviour of negatively buoyant jets in immiscible ambient fluid

2011 ◽  
Vol 52 (1) ◽  
pp. 261-271 ◽  
Author(s):  
A. Geyer ◽  
J. C. Phillips ◽  
M. Mier-Torrecilla ◽  
S. R. Idelsohn ◽  
E. Oñate
Proceedings ◽  
2018 ◽  
Vol 2 (11) ◽  
pp. 572 ◽  
Author(s):  
Anastasia Fragkou ◽  
Panos Papanicolaou

A mathematical model has been employed to determine the characteristics of Boussinesq round buoyant jets which are injected horizontally or at an angle to horizontal, into a homogeneous, calm ambient. The solution of a system of three conservation first order nonlinear differential equations was obtained with a 4th Runge-Kutta scheme, using an entrainment coefficient which is related to the local Richardson number of the flow. Two types of positively and negatively buoyant jets were investigated (i) those where the buoyancy is a function of salinity henceforth called saline jets, and (ii) those where the buoyancy is a function of the temperature difference between jet and ambient fluid, henceforth called thermal jets.


Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 232
Author(s):  
Panos N. Papanicolaou ◽  
George C. Stamoulis

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.


Water ◽  
2018 ◽  
Vol 10 (6) ◽  
pp. 726 ◽  
Author(s):  
Simone Ferrari ◽  
Maria Badas ◽  
Giorgio Querzoli

Author(s):  
M A Azim

Two types of isothermal free jets, named positively and negatively buoyant, have been studied numerically to discern the effect of surrounding temperatures on their flow dynamics. Turbulence closure in those jets was achieved by standard k - ε model. The governing equations were solved using Implicit θ-Scheme and Tridiagonal Matrix Algorithm. Calculations were made for the jets having constant temperature at 20 °C and by varying surrounding temperatures from 20°C to 1000°C. It is clear that negatively buoyant jets but not the positively buoyant jets are nearly invariant to the change in surrounding temperatures compared to non-buoyant jet. Change in fluid dynamical behaviour of positively buoyant jets due to surrounding temperature change seems promising as it may offer the advantages of fuel jets in high-temperature air combustion.


Water ◽  
2012 ◽  
Vol 4 (3) ◽  
pp. 750-768
Author(s):  
Raed Bashitialshaaer ◽  
Magnus Larson ◽  
Kenneth M. Persson

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