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Entrainment, diffusion and effective compressibility in a self-similar turbulent jet

hal.structure.identifierLaboratoire de Physique de l'ENS Lyon [Phys-ENS]
dc.contributor.authorBASSET, Thomas
hal.structure.identifierPortland State University [Portland] [PSU]
dc.contributor.authorVIGGIANO, Bianca
hal.structure.identifierLaboratoire Ondes et Matière d'Aquitaine [LOMA]
dc.contributor.authorBAROIS, Thomas
hal.structure.identifierHélium : du fondamental aux applications [NEEL - HELFA]
dc.contributor.authorGIBERT, Mathieu
hal.structure.identifierLaboratoire des Écoulements Géophysiques et Industriels [Grenoble] [LEGI]
dc.contributor.authorMORDANT, Nicolas
hal.structure.identifierPortland State University [Portland] [PSU]
dc.contributor.authorCAL, Raúl Bayoán
hal.structure.identifierLaboratoire de Physique de l'ENS Lyon [Phys-ENS]
dc.contributor.authorVOLK, Romain
hal.structure.identifierLaboratoire de Physique de l'ENS Lyon [Phys-ENS]
dc.contributor.authorBOURGOIN, Mickaël
dc.date.issued2022
dc.identifier.issn0022-1120
dc.description.abstractEnAn experimental Lagrangian study based on particle tracking velocimetry has been completed in an incompressible turbulent round water jet freely spreading into water. The jet is seeded with tracers only through the nozzle: inhomogeneous seeding called nozzle seeding. The Lagrangian flow tagged by these tracers therefore does not contain any contribution from particles entrained into the jet from the quiescent surrounding fluid. The mean velocity field of the nozzle seeded flow, $\langle \boldsymbol {U}_{\boldsymbol {\varphi }} \rangle$ , is found to be essentially indistinguishable from the global mean velocity field of the jet, $\langle \boldsymbol {U} \rangle$ , for the axial velocity while significant deviations are found for the radial velocity. This results in an effective compressibility of the nozzle seeded flow for which $\boldsymbol {\nabla }\boldsymbol {\cdot } \langle \boldsymbol {U}_{\boldsymbol {\varphi }} \rangle \neq 0$ even though the global background flow is fully incompressible. By using mass conservation and self-similarity, we quantitatively explain the modified radial velocity profile and analytically express the missing contribution associated with entrained fluid particles. By considering a classical advection–diffusion description, we explicitly connect turbulent diffusion of mass (through the turbulent diffusivity $K_T$ ) and momentum (through the turbulent viscosity $\nu _T$ ) to entrainment. This results in new practical relations to experimentally determine the non-uniform spatial profiles of $K_T$ and $\nu _T$ (and hence of the turbulent Prandtl number $\sigma _T = \nu _T/K_T$ ) from simple measurements of the mean tracer concentration and axial velocity profiles. Overall, the proposed approach based on nozzle seeded flow gives new experimental and theoretical elements for a better comprehension of turbulent diffusion and entrainment in turbulent jets.
dc.description.sponsorshipIDEXLYON - ANR-16-IDEX-0005
dc.language.isoen
dc.publisherCambridge University Press (CUP)
dc.title.enEntrainment, diffusion and effective compressibility in a self-similar turbulent jet
dc.typeArticle de revue
dc.identifier.doi10.1017/jfm.2022.638
dc.subject.halPhysique [physics]/Mécanique [physics]/Mécanique des fluides [physics.class-ph]
dc.subject.halPhysique [physics]/Physique [physics]/Dynamique des Fluides [physics.flu-dyn]
bordeaux.journalJournal of Fluid Mechanics
bordeaux.pageA29
bordeaux.volume947
bordeaux.peerReviewedoui
hal.identifierhal-03762366
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-03762366v1
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