Assessment of a miniature four-roll mill and a cross-slot microchannel for high-strain-rate stagnation point flows

Farzan Akbaridoust, Jimmy Philip, Ivan Marusic

Research output: Contribution to journalArticleResearchpeer-review

6 Citations (Scopus)


Stagnation point flows have been widely used to study the deformation and break-up of objects in two-dimensional pure straining flows. Here, we report a systematic study of the characterisation of stagnation point flows in two devices, a miniature Taylors fourroll mill and a cross-slot microchannel. The aim of the study is to find the best platform suitable for investigating the effect of strain rate on the mechanical properties of waterborne microorganisms. Using micro-PIV, the velocity field and the strain rates in both devices were measured at different flow rates and compared with an ideal hyperbolic stagnation point flow. The cross-slot microchannel was found to be a better experimental device than the miniature four-roll mill for the purpose of confining micron-sized objects in a controlled stagnation point flow. This is mainly due to the difficulty of maintaining a fixed location for the stagnation point within one micron in the miniature four-roll mill and achieving high strain rates beyond 10 s-1. However, with no moving parts, the cross-slot microchannel was found to maintain a steady flow, with the stagnation point varying less than one micron at a cross-junction of 400 × 400 μm2, and was able to reach uniform strain rates up to 140 s-1.

Original languageEnglish
Article number045302
Number of pages18
JournalMeasurement Science and Technology
Issue number4
Publication statusPublished - 14 Mar 2018
Externally publishedYes


  • cross-slot microchannel
  • extensional flow
  • four-roll mill
  • high strain rate flows
  • micro-PIV
  • microfluidics
  • stagnation point

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