A new linearly unstable mode in the core-annular flow of two immiscible fluids

Sahu, Kirti Chandra (2021) A new linearly unstable mode in the core-annular flow of two immiscible fluids. Journal of Fluid Mechanics, 918 (A11). ISSN 0022-1120

Full text not available from this repository. (Request a copy)


The linear stability characteristics of pressure-driven core-annular pipe flow of two immiscible fluids are considered to investigate the effects of the density and viscosity ratios, the Reynolds number, the interface location and the interfacial tension. Both liquid-liquid and gas-liquid systems are examined. A new type of interfacial mode associated with the axisymmetric and corkscrew perturbations is discovered for certain ranges of the viscosity and density ratios in the immiscible liquid-liquid system. Two distinct unstable regions at long and short wavelengths are observed. The long-wavelength unstable region forms a close loop, indicating that it is not a Tollmien-Schlichting mode. The new interfacial mode observed in the present study is similar to that discovered by Mohammadi & Smits (J. Fluid Mech., vol. 826, 2017, pp. 128-157) in two-layer Couette flow for low viscosity ratios. In contrast to the two distinct unstable regions found in the immiscible configuration, the corresponding miscible system contains only one unstable mode. It is found that, in the liquid-liquid systems, the corkscrew (axisymmetric) perturbation is dominant when the annular fluid is less (more) viscous than the core fluid. On the other hand, the axisymmetric perturbation is always the dominant one in the gas-liquid system. In gas-liquid systems, the interfacial tension stabilises the short-wave and destabilises the long-wave perturbations, while increasing the interface radius stabilises the flow due to the presence of a plug region in the pipe.

[error in script]
IITH Creators:
IITH CreatorsORCiD
Sahu, Kirti Chandrahttp://orcid.org/0000-0002-7357-1141
Item Type: Article
Uncontrolled Keywords: core-annular flow, gas/liquid flow, Liquids, Reynolds number, Viscosity
Subjects: Chemical Engineering
Chemical Engineering > Technology of industrial chemicals
Chemical Engineering > Fluid Mechanics
Chemical Engineering > Explosives, fuels, related products
Chemical Engineering > Food and Beverage technology
Chemical Engineering > Oils, fats, waxes, gases
Chemical Engineering > Ceramic and allied technologies
Chemical Engineering > Cleaning, color, coating, related technologies
Chemical Engineering > Organic products
Chemical Engineering > Metallurgy
Chemical Engineering > Biochemical Engineering
Divisions: Department of Chemical Engineering
Depositing User: . LibTrainee 2021
Date Deposited: 27 May 2021 09:49
Last Modified: 27 May 2021 09:49
URI: http://raiith.iith.ac.in/id/eprint/7848
Publisher URL: http://doi.org/10.1017/jfm.2021.349
OA policy: https://v2.sherpa.ac.uk/id/publication/1706
Related URLs:

Actions (login required)

View Item View Item
Statistics for RAIITH ePrint 7848 Statistics for this ePrint Item