A damping phenomenon in viscoelastic fluids
1 IATE, INRA-CIRAD-UMII-Supagro - 2 place Pierre Viala, 34000 Montpellier, France
2 Laboratory of Reactions and Process Engineering, University of Lorraine, CNRS 1 rue Grandville, BP 20451, 54001 Nancy Cedex, France
Received: 11 December 2013
Accepted: 5 March 2014
Flow fields behind a sphere settling in polymeric fluids are investigated using a Particle Image Velocimetry (PIV) technique. Complex features including both a negative wake and a surrounding cone are quantified. In particular, an oscillation zone, which takes place behind the negative wake, is identified for the first time. A physical understanding of various phenomena involved in the wake is gained. The damping phenomenon can be attributed to the viscoelastic properties and the surrounding cone stems from a propagation front of lateral viscoelastic wave emitted by the settling sphere. The oscillation frequency and open angle of the surrounding cone are theoretically related to a viscoelastic Mach number. Satisfactory agreement with experiments is observed.
PACS: 47.50.-d – Non-Newtonian fluid flows / 83.60.Uv – Wave propagation, fracture, and crack healing
© EPLA, 2014