RT Journal Article
T1 Negatively buoyant starting jets
A1 Marugán Cruz, Carolina
A1 Rodríguez-Rodríguez, Javier
A1 Martínez-Bazán, C.
AB The initial development of negatively buoyant jets has been investigated experimentally and numerically, focusing on the role played by gravity in the evolution of the leading vortex ring. Under the experimental conditions considered in this work, the densimetric Froude number, Fr= ρjU²j/[(ρ₀ − ρj) gD] , which represents the ratio between the jet momentum and the buoyancy forces,emerges as the most relevant parameter characterizing the dynamics of the flow. Two different flowregimes have been observed depending on the Froude number: for sufficiently small Fr, the vortexring generated initially is pushed radially away by gravity forces before it has time to detach fromthe shear layer originating at the orifice. On the other hand, when the Froude number is larger thana critical value, Fr> Frc∼ 1, the vortex ring detaches from the injection orifice and propagatesdownstream into the stagnant ambient followed by a trailing jet until it eventually reaches amaximum penetration depth. In order to clarify the mechanisms leading to the transition between thetwo regimes, and to gain physical understanding of the formation dynamics of negatively buoyantstarting jets, the total and the vortex circulation, as well as the trajectory of the vortex center, havebeen measured and compared to the case of neutrally buoyant jets. Finally, based on theexperimental measurements and on the results of the numerical computations, a kinematic modelthat successfully describes the evolution of both total circulation and vortex trajectory isproposed.
PB American Institute of Physics
SN 1070-6631 (print)
SN 1089-7666 (online)
YR 2009
FD 2009-11
LK https://hdl.handle.net/10016/13449
UL https://hdl.handle.net/10016/13449
LA eng
NO This work was supported by the Spanish Ministry of Education under Project Nos. DPI2008-06624-C03-02 and ENE2008-0615-C04. This work has been extracted from thePh.D. thesis of Marugán-Cruz
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RD 3 may. 2024