Stirring by squirmers

Details Stirring by squirmers Stirring by squirmers

2010-07-10

arxiv.org/abs/1007.1740v2

Journal of Fluid Mechanics 669, 167-177, 2011

Physics

Fluid Dynamics

10 pages, 12 figures. PDFLaTeX with JFM style (included). Accepted for publication in Journal of Fluid Mechanics

Scientific paper

10.1017/S002211201000563X

We analyse a simple 'Stokesian squirmer' model for the enhanced mixing due to swimming micro-organisms. The model is based on a calculation of Thiffeault & Childress [Physics Letters A, 374, 3487 (2010), arXiv:0911.5511], where fluid particle displacements due to inviscid swimmers are added to produce an effective diffusivity. Here we show that for the viscous case the swimmers cannot be assumed to swim an infinite distance, even though their total mass displacement is finite. Instead, the largest contributions to particle displacement, and hence to mixing, arise from random changes of direction of swimming and are dominated by the far-field stresslet term in our simple model. We validate the results by numerical simulation. We also calculate nonzero Reynolds number corrections to the effective diffusivity. Finally, we show that displacements due to randomly-swimming squirmers exhibit PDFs with exponential tails and a short-time superdiffusive regime, as found previously by several authors. In our case, the exponential tails are due to 'sticking' near the stagnation points on the squirmer's surface.

Affiliated with

Also associated with

No associations

Rating

Stirring by squirmers 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 Stirring by squirmers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stirring by squirmers will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-563067