LAMINAR FLOW REGIMES FOR RIGID-SPHERE SUSPENSIONS.
Abstract
An experimental study is made of the flow of density-matched rigid sphere suspensions in rigid cylindrical tubes at low tube Reynolds numbers (0.001 to 100). It is found that a number of distinct types of flow exist within the laminar range whose character is determined by particle concentration, ratio of particle diameter to tube diameter, and Reynolds number. These flows are consistent with those seen by other investigators and in some cases bear a strong resemblance to the flow in the living microcirculation. In particular, the phenomena of 'plasma skimming,' the 'tubular pinch effect,' and a random-type of unsteady 'tumbling' flow are each observed for particular combinations of the above variables. It is found that for particle concentrations between about 1 and 30 percent and ratios of particle-diameter to tube-diameter between 3/16 and 7/16, there is a dramatic change in flow regime at a tube Reynolds number of about 10. Below that value, particle interactions produce a complex, unsteady particle motion involving significant radial excursions. Above that value, particle interactions virtually cease, nearly all particles move at a constant velocity parallel to the tube axis, and no particles remain on the vessel wall. This change in flow regime is accompanied by a sudden drop in relative viscosity to approximately that predicted by the non-interaction theory of Einstein. It is shown that the fluid suspension is in all cases Newtonian and the motion is in all cases laminar. The particle interactions associated with the above phenomenon are therefore not to be confused with turbulence. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 28, 1966
- Accession Number
- AD0629312
Entities
People
- Alvin H. Sacks
- E. Glenn Tickner