A critical review of the drag force on a sphere in the transition flow regime

C.L. Bailey, Robert W. Barber, David Emerson, Duncan A. Lockerby, Jason Reese

Research output: Chapter in Book/Report/Conference proceedingChapter

12 Citations (Scopus)


Improvements in micro-fabrication techniques are enabling Micro-Electro-Mechanical-Systems to be constructed with sub-micron feature sizes. At this scale, even at standard atmospheric conditions, the flow is in the transition regime. This paper considers the range 0.1 < Kn < 1, where non-equilibrium effects can be appreciable, and specifically illustrates problems involving non-planar surfaces by analyzing the drag force for low speed, incompressible flow past an unconfined microsphere. A critical comparison is made between experimental data, analytical solutions derived from kinetic theory, Grad's thirteen-moment equations, and the Navier-Stokes equations with first- and second-order treatment of the slip boundary. The results, even for this simple geometry, highlight major problems in predicting the drag in the transition flow regime for non-kinetic schemes.
Original languageEnglish
Title of host publicationRarefied Gas Dynamics
Number of pages6
Publication statusPublished - 10 Jul 2004
Event24th International Symposium on Rarefied Gas Dynamics, Bari, Italy -
Duration: 1 Jan 1900 → …

Publication series

NameAIP Conference Proceedings
PublisherAmerican Institute of Physics


Conference24th International Symposium on Rarefied Gas Dynamics, Bari, Italy
Period1/01/00 → …


  • drag
  • Knudsen flow
  • microfluidics

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