Microtextured surfaces can reduce friction in lubricated dynamic contact. However, no prior experimental study has explored the dimensionless parameter space of Reynolds number and dimensionless gap, since normal force is easier to control than the fluid film thickness. Here, we develop a custom precision-aligned setup for gap-controlled tribo-rheometry based on a rotational rheometer. The novel experimental setup allows for measurement of full film lubrication of parallel disks down to 20 μm gaps with gap precision ±3 μm, over a range of Reynolds numbers. We show for the first time in gap-controlled conditions that microtextured surfaces reduce friction. The reduction in dimensionless shear stress is nearly independent of velocity for Re<10 which matches computational results in this work.

Original languageEnglish (US)
Pages (from-to)123-132
Number of pages10
JournalTribology International
Issue numberPA
StatePublished - Feb 2015


  • Full film lubrication
  • Gap-control
  • Microtextures
  • Reynolds number

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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