Document Type

Article

Publication Date

2014

DOI

10.1098/rsta.2013.0362

Publication Title

Philosophical Transactions of the Royal Society A: Mathematical Physical and Engineering Sciences

Volume

372

Issue

2029

Pages

20130362 (21 pp)

Abstract

We consider the dilute regime of active suspensions of liquid crystalline polymers (LCPs), addressing issues motivated by our kinetic model and simulations in Forest et al. (Forest et al. 2013 Soft Matter 9, 5207-5222 (doi:10.1039/c3sm27736d)). In particular, we report unsteady two-dimensional heterogeneous flow-orientation attractors for pusher nanorod swimmers at dilute concentrations where passive LCP equilibria are isotropic. These numerical limit cycles are analogous to longwave (homogeneous) tumbling and kayaking limit cycles and two-dimensional heterogeneous unsteady attractors of passive LCPs in weak imposed shear, yet these states arise exclusively at semi-dilute concentrations where stable equilibria are nematic. The results in Forest et al. mentioned above compel two studies in the dilute regime that complement recent work of Saintillan & Shelley (Saintillan & Shelley 2013 C. R. Physique 14, 497-517 (doi: 10.1016/j.crhy.2013.04.001)): linearized stability analysis of the isotropic state for nanorod pushers and pullers; and an analytical-numerical study of weakly and strongly sheared active polar nanorod suspensions to capture how particle-scale activation affects shear rheology. We find that weakly sheared dilute puller versus pusher suspensions exhibit steady versus unsteady responses, shear thickening versus thinning and positive versus negative first normal stress differences. These results further establish how sheared dilute nanorod pusher suspensions exhibit many of the characteristic features of sheared semi-dilute passive nanorod suspensions.

Comments

Web of Science: "Free full-text from publisher."

Original Publication Citation

Forest, M. G., Phuworawong, P., Wang, Q., & Zhou, R. H. (2014). Rheological signatures in limit cycle behaviour of dilute, active, polar liquid crystalline polymers in steady shear. Philosophical Transactions of the Royal Society A: Mathematical Physical and Engineering Sciences, 372(2029), 20130362. doi:10.1098/rsta.2013.0362

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