Convective and diffusive effects on particle transport in asymmetric periodic capillaries

PLoS One. 2017 Aug 25;12(8):e0183127. doi: 10.1371/journal.pone.0183127. eCollection 2017.

Abstract

We present here results of a theoretical investigation of particle transport in longitudinally asymmetric but axially symmetric capillaries, allowing for the influence of both diffusion and convection. In this study we have focused attention primarily on characterizing the influence of tube geometry and applied hydraulic pressure on the magnitude, direction and rate of transport of particles in axi-symmetric, saw-tooth shaped tubes. Three initial value problems are considered. The first involves the evolution of a fixed number of particles initially confined to a central wave-section. The second involves the evolution of the same initial state but including an ongoing production of particles in the central wave-section. The third involves the evolution of particles a fully laden tube. Based on a physical model of convective-diffusive transport, assuming an underlying oscillatory fluid velocity field that is unaffected by the presence of the particles, we find that transport rates and even net transport directions depend critically on the design specifics, such as tube geometry, flow rate, initial particle configuration and whether or not particles are continuously introduced. The second transient scenario is qualitatively independent of the details of how particles are generated. In the third scenario there is no net transport. As the study is fundamental in nature, our findings could engender greater understanding of practical systems.

MeSH terms

  • Biological Transport
  • Capillaries / physiology*
  • Convection
  • Diffusion
  • Models, Theoretical

Grants and funding

LRW gratefully received funding in the form of Discovery Grant #DP1096282 from the Australian Research Council (http://www.arc.gov.au/) for the support of NI. The funders had no role in study, design, data collection and analysis, decision to publish, or preparation of the manuscript.