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Slip velocity and drag law in a liquid‐liquid homogeneous dispersed flow
Author(s) -
Augier Frédéric,
Masbernat Olivier,
Guiraud Pascal
Publication year - 2003
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.690490907
Subject(s) - drag coefficient , drag , terminal velocity , mechanics , reynolds number , two phase flow , stokes flow , thermodynamics , flow (mathematics) , materials science , physics , turbulence
Local measurements of phase velocities and phase fraction in a dense liquid‐liquid homogeneous flow were done based on an application of PIV with a refractive index matching technique. This technique allowed to measure simultaneously both phase velocities and phase fraction fields, as well as the drop mean diameter in a vertical cocurrent flow of n‐heptane dispersed in an aqueous solution of glycerin. The evolution of the relative velocity as a function of the phase fraction (0–0.4) was studied with moderate particle Reynolds numbers (10–100) for drops behaving as spherical rigid particles. A local drag coefficient was derived from these measurements. The calculated mean relative velocity as a function of the local phase fraction with existing classical drag coefficient laws showed significant discrepancies with the measurements overestimated. Thus, the drag coefficient variation rate as a function of the phase fraction was underestimated by the models. The evolution of the normalized velocity (by the terminal velocity) as a function of the phase fraction was predicted correctly with mixture viscosity models in a creeping flow regime.