Dataset Information

Anisotropic particles align perpendicular to the flow direction in narrow microchannels.

ABSTRACT: The flow orientation of anisotropic particles through narrow channels is of importance in many fields, ranging from the spinning and molding of fibers to the flow of cells and proteins through thin capillaries. It is commonly assumed that anisotropic particles align parallel to the flow direction. When flowing through narrowed channel sections, one expects the increased flow rate to improve the parallel alignment. Here, we show by microfocus synchrotron X-ray scattering and polarized optical microscopy that anisotropic colloidal particles align perpendicular to the flow direction after passing a narrow channel section. We find this to be a general behavior of anisotropic colloids, which is also observed for disk-like particles. This perpendicular particle alignment is stable, extending downstream throughout the remaining part of the channel. We show by microparticle image velocimetry that the particle reorientation in the expansion zone after a narrow channel section occurs in a region with considerable extensional flow. This extensional flow is promoted by shear thinning, a typical property of complex fluids. Our discovery has important consequences when considering the flow orientation of polymers, micelles, fibers, proteins, or cells through narrow channels, pipes, or capillary sections. An immediate consequence for the production of fibers is the necessity for realignment by extension in the flow direction. For fibrous proteins, reorientation and stable plug flow are likely mechanisms for protein coagulation.

SUBMITTER: Trebbin M

PROVIDER: S-EPMC3637725 | biostudies-literature | 2013 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Anisotropic particles align perpendicular to the flow direction in narrow microchannels.

Trebbin Martin M Steinhauser Dagmar D Perlich Jan J Buffet Adeline A Roth Stephan V SV Zimmermann Walter W Thiele Julian J Förster Stephan S

Proceedings of the National Academy of Sciences of the United States of America 20130408 17

The flow orientation of anisotropic particles through narrow channels is of importance in many fields, ranging from the spinning and molding of fibers to the flow of cells and proteins through thin capillaries. It is commonly assumed that anisotropic particles align parallel to the flow direction. When flowing through narrowed channel sections, one expects the increased flow rate to improve the parallel alignment. Here, we show by microfocus synchrotron X-ray scattering and polarized optical mic ...[more]

PMID: 23569240

Similar Datasets

Project description:Suspended particles flowing through complex porous spaces exhibit clogging mechanisms determined by factors including their size, deformability, and the geometry of the confinement. This study describes the clogging of rigid particles in a microfluidic device made up of parallel microchannels that taper from the inlet to the outlet, where the constriction width is approximately equal to the particle size. This converging geometry summarizes the dynamics of clogging in flow channels with constrictions that narrow over multiple length scales. Our novel approach allows the investigation of suspension flow dynamics in confined systems where clogs are formed both by sieving and bridging mechanisms simultaneously. Here, flow tests are conducted at constant driving pressures for different particle volume fractions, and a power-law decay which appears to be peculiar to the channels' tapered geometry is observed in all cases. Compared to non-tapered channels, the power-law behavior shows flowrate decay is significantly weaker in tapered channels. This weaker flowrate decay is explained by the formation of discontinuous clogs within each channel. Micrographs of the clogged channels reveal clogs do not grow continuously from their initial positions around the channels' outlet. Rather, new clogs spanning the width of the channel at their points of inception are successively formed as the cake grows toward the inlet area in each microchannel. The results show changes in particle volume fraction at constant driving pressure affect the clogging rate without impacting the underlying dynamics. Unexpectedly, analyses of the particles packing behavior in the microchannels, and post-clogging permeability of the microfluidic devices, reveal the presence of two distinct regimes of driving pressure, though only a small portion of the total device volume and channels surface area are occupied by clogs, regardless of the particle volume fraction. This novel investigation of discontinuous clogging over multiple particle diameters provides unique insights into additional mechanisms to control flow losses in filtration and other confined systems.

Dataset Information

Anisotropic particles align perpendicular to the flow direction in narrow microchannels.

Publications

Anisotropic particles align perpendicular to the flow direction in narrow microchannels.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets