Fluid particle diffusion through high-hematocrit blood flow within a capillary tube

Maryam Saadatmand, Takuji Ishikawa, Noriaki Matsuki, Mohammad Jafar Abdekhodaie, Yohsuke Imai, Hironori Ueno, Takami Yamaguchi

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)


Fluid particle diffusion through blood flow within a capillary tube is an important phenomenon to understand, especially for studies in mass transport in the microcirculation as well as in solving technical issues involved in mixing in biomedical microdevices. In this paper, the spreading of tracer particles through up to 20% hematocrit blood, flowing in a capillary tube, was studied using a confocal micro-PTV system. We tracked hundreds of particles in high-hematocrit blood and measured the radial dispersion coefficient. Results yielded significant enhancement of the particle diffusion, due to a micron-scale flow-field generated by red blood cell motions. By increasing the flow rate, the particle dispersion increased almost linearly under constant hematocrit levels. The particle dispersion also showed near linear dependency on hematocrit up to 20%. A scaling analysis of the results, on the assumption that the tracer trajectories were unbiased random walks, was shown to capture the main features of the results. The dispersion of tracer particles was about 0.7 times that of RBCs. These findings provide good insight into transport phenomena in the microcirculation and in biomedical microdevices.

Original languageEnglish
Pages (from-to)170-175
Number of pages6
JournalJournal of Biomechanics
Issue number1
Publication statusPublished - 2011 Jan 4


  • Biofluid mechanics
  • Capillary tube
  • Confocal micro-PTV
  • Diffusion
  • Red blood cell


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