Picture of industrial chimneys polluting horizon

Open Access research shaping international environmental governance...

Strathprints makes available scholarly Open Access content exploring environmental law and governance, in particular the work of the Strathclyde Centre for Environmental Law & Governance (SCELG) based within the School of Law.

SCELG aims to improve understanding of the trends, challenges and potential solutions across different interconnected areas of environmental law, including capacity-building for sustainable management of biodiversity, oceans, lands and freshwater, as well as for the fight against climate change. The intersection of international, regional, national and local levels of environmental governance, including the customary laws of indigenous peoples and local communities, and legal developments by private actors, is also a signifcant research specialism.

Explore Open Access research by SCELG or the School of Law. Or explore all of Strathclyde's Open Access research...

Viscoelastic instabilities in microscale flows

Galindo-Rosales, Francisco J and Campo-Deaño, Laura and Sousa, P.C. and Ribeiro, Vera M. and Oliveira, Monica and Alves, M.A. and Pinho, F.T. (2014) Viscoelastic instabilities in microscale flows. Experimental Thermal and Fluid Science. pp. 128-139. ISSN 0894-1777

[img] PDF (Oliveira-etal-ETFS-2014-Viscoelastic-instabilities-in-micro-scale-flows-2014)
Oliveira_etal_ETFS_2014_Viscoelastic_instabilities_in_micro_scale_flows_2014.pdf
Accepted Author Manuscript
License: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 logo

Download (2MB)

Abstract

Many artificial and natural fluids contain macromolecules, particles or droplets that impart complex flow behavior to the fluid. This complex behavior results in a non-linear relationship between stress and deformation standing in between Newton’s law of viscosity for an ideal viscous liquid and Hooke’s law for an ideal elastic material. Such non-linear viscoelastic behavior breaks down flow reversibility under creeping flow conditions, as encountered at the micro-scale, and can lead to flow instabilities. These instabilities offer an alternative to the development of systems requiring unstable flows under conditions where chaotic advection is unfeasible. Flows of viscoelastic fluids are characterized by the Weissenberg (Wi) and Reynolds (Re) numbers, and at the micro-scale flow instabilities occur in regions in the Wi–Re space typically unreachable at the macro-scale, namely high Wi and low Re. In this paper, we review recent experimental work by the authors on the topic of elastic instabilities in flows having a strong extensional component, including: flow through a hyperbolic contraction followed by a sudden expansion; flow in a microfluidic diode and in a flow focusing device; flow around a confined cylinder; flow through porous media and simplified porous media analogs. These flows exhibit different types of flow transitions depending on geometry, Wi and Re, including: transition from a steady symmetric to a steady asymmetric flow, often followed by a second transition to unsteady flow at high Wi; direct transition between steady symmetric and unsteady flows.