Reference : Dynamics of Elasto-Inertial Turbulence in Flows with Polymer Additives
Scientific conferences in universities or research centers : Scientific conference in universities or research centers
Engineering, computing & technology : Mechanical engineering
Engineering, computing & technology : Chemical engineering
http://hdl.handle.net/2268/136005
Dynamics of Elasto-Inertial Turbulence in Flows with Polymer Additives
English
Terrapon, Vincent mailto [Université de Liège - ULg > Département d'aérospatiale et mécanique > Modélisation et contrôle des écoulements turbulents >]
Dubief, Yves [University of Vermont, UVM > Mechanical Engineering > M2CE > >]
Soria, Julio [Monash University > Mechanical Engineering > Laboratory for Turbulence Research in Aerospace & Combustion > >]
7-Dec-2012
International
Invited Seminar
07-12-2012
Von Karman Institute for Fluid Dynamics (VKI)
Rhodes-St-Genese
Belgium
[en] Elasto-Inertial Turbulence ; Polymers ; Drag reduction ; Transition ; Viscoelasticity ; Turbulence
[en] Elasto-inertial turbulence is a new state of turbulence that may occur in certain viscoelastic flows, in particular flows with polymer additives. The dynamics of elasto-inertial turbulence is here investigated numerically from the perspective of the coupling between polymer dynamics and flow structures. The resulting mechanism helps resolve a long standing controversy in the understanding of polymer drag reduction and explains the phenomenon of early turbulence, or onset of turbulence at lower Reynolds numbers than for Newtonian flows, previously observed in polymeric flows.
In particular, we show that the introduction of small perturbations into the polymeric flow excites the unstable nature of the nonlinear advection term, resulting in the formation of sheets or cliffs of polymer stretch. These sheets of high polymer stretch, hosting a significant increase in extensional viscosity, create a strong local anisotropy, with a formation of local low-speed jet-like flow. The response of the flow is through pressure, whose role is to redistribute energy across components of momentum, resulting in the formation of waves, or trains of alternating rotational and straining motions. The mechanism shares some similarity with the Kelvin-Helmholtz instability, except that the thickness of these sheets is too close to the Kolmogorov scale for vortices to be created. Once triggered, EIT is self-sustained since the elastic instability creates the very velocity fluctuations it feeds upon.
Researchers ; Professionals ; Students
http://hdl.handle.net/2268/136005
FP7 ; 304073 - VISCELTURBFLOW - Computational study of macro- and microscopic turbulence controlled by polymer additives

File(s) associated to this reference

Fulltext file(s):

FileCommentaryVersionSizeAccess
Open access
121207 - VKI2012 - Terrapon.pdfAuthor postprint18.58 MBView/Open

Bookmark and Share SFX Query

All documents in ORBi are protected by a user license.