Active microrheology in the continuum limit: can the macrorheology be recovered?

Details Active microrheology in the continuum limit: can the macrorheology be recovered? Active microrheology in the continuum limit: can the macrorheology be recovered?

2005-07-23

arxiv.org/abs/cond-mat/0507551v1

Physics

Condensed Matter

Soft Condensed Matter

4 pages, 1 figure

Scientific paper

Active microrheology differs from its passive counterpart in that the probe is actively forced through the material, rather than allowed to diffuse. Unlike in passive microrheology, active forcing allows the material to be driven out of equilibrium, and its nonlinear response to be probed. However, this also renders inoperable the fluctuation-dissipation theorem used to justify passive microrheology. Here we explore a question at the heart of active microrheology: are its results consistent with macrorheology? We study a simple model material -- a generalized Newtonian fluid, with a small but arbitrary shear-rate-dependent component -- and derive a general expression for dissipation due to probe motion, which remarkably does not require the non-Newtonian flow to be solved. We demonstrate that the straightforward application of active microrheology gives results that are inconsistent with macrorheology, even when the probe is large enough for material to behave as a continuum, unless the forcing is gentle enough to probe only the linear response. Regardless, each technique encodes information about the material; if suitably interpreted, the (macro-) constitutive relation can indeed be recovered from the microrheological data. We emphasize that more, rather than less, information would be obtained if the two methods disagree.

Affiliated with

Also associated with

No associations

Rating

Active microrheology in the continuum limit: can the macrorheology be recovered? does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Active microrheology in the continuum limit: can the macrorheology be recovered?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Active microrheology in the continuum limit: can the macrorheology be recovered? will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-544508