Premium
External flows of viscoelastic materials: Fluid property restrictions on the use of velocity‐sensitive probes
Author(s) -
Metzner A. B.,
Astarita Gianni
Publication year - 1967
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690130327
Subject(s) - viscoelasticity , deborah number , dimensionless quantity , mechanics , stagnation point , boundary layer , flow (mathematics) , boundary (topology) , materials science , classical mechanics , physics , mathematics , thermodynamics , mathematical analysis , heat transfer
The more pronounced macroscopic features of flows of viscoelastic materials around submerged objects are considered in the light of restriction imposed on the flow by the Deborah number, a dimensionless group representing a ratio of time scales of the fluid and the flow process. It is seen that one major effect is to thicken the boundary layer appreciably in the region of the leading edge or stagnation point of the object in the fluid; depending on the shape of the object this thickening of the boundary layer may be felt for appreciable distances into the velocity field. The influence of these and other effects on the use of probes for determination of point values of the velocity of viscoelastic fluids is considered in some detail. The general effect is to impose strong restrictions on the use of such probes and on the interpretation of measurements made with them. These predicted limitations are supported, in a general way, by recent experimental measurements; thus the present macroscopic analysis appears to define several major effects to be considered in subsquent, more detailed investigations.