Bulletin of the American Physical Society
71st Annual Meeting of the APS Division of Fluid Dynamics
Volume 63, Number 13
Sunday–Tuesday, November 18–20, 2018; Atlanta, Georgia
Session A36: Suspensions: Confined Flows
8:00 AM–9:57 AM,
Sunday, November 18, 2018
Georgia World Congress Center
Room: B408
Chair: Roseanna Zia, Stanford University
Abstract ID: BAPS.2018.DFD.A36.2
Abstract: A36.00002 : Experimental investigation of viscoelastic effects in wavy-microchannel flow*
8:13 AM–8:26 AM
Presenter:
Simon J Haward
(Okinawa Inst of Sci & Tech)
Authors:
Simon J Haward
(Okinawa Inst of Sci & Tech)
Jacob Page
(Univ of Bristol, University of Cambridge)
Tamer A Zaki
(Johns Hopkins Univ)
Amy Q Shen
(Okinawa Inst of Sci & Tech)
We examine Newtonian and viscoelastic flows through slit microchannels depth d with a sinusoidal wall profile amplitude A<< d, wavelength λ and a range of dimensionless depths 0.6< α = 2πd/λ <10. Dilute solutions of high molecular weight polymer in solvents of various viscosity provide fluids with elasticity numbers 0.001<El <44. Flow velocimetry is performed in the channels over a range of flow rates. For all fluids, the wavy wall causes small perturbations (~3 %) to the Poiseuille base flow. A subtle interplay between El, α, and the imposed flow rate affects the form of the perturbation and its depth of penetration P into the channel. Our experiments support recent theoretical predictions of a ‘critical layer’ in the channel located at a dimensionless depth Σ~El0.5. Our results are consistent with the existence of a phase diagram in α-Σ parameter space showing three regimes classified as “shallow-elastic”, “deep-elastic” and “transcritical”. In the transcritical regime (defined by α > Σ, Σ < 1), the critical layer drives a surprising nonlocal amplification of the perturbation, significantly influencing P.
*SJH and AQS acknowledge the support of OIST with funding from the Cabinet Office, Govt of Japan, and funding from JSPS (Grants nos 18K03958 and 17K06173, respectively).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2018.DFD.A36.2
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