Negative wake behind bubbles in non-newtonian liquids

Research output: Contribution to journalLetterResearch

Abstract

Gas bubbles rising by gravity in non-Newtonian elastic liquids are different to gas bubbles in viscous Newtonian fluids in at least two ways. First, the bubbles in the non-Newtonian liquids often have a peculiar tip at the rear pole, and second, the terminal rise velocity versus volume curve often has a discontinuity at a certain `critical' volume. To investigate this unusual flow situation further laser-Doppler anemometry was used to measure the liquid velocity in the weak behind air bubbles in a non-Newtonian liquid. The measurements reveal the unexpected result that the liquid velocity behind the bubbles is in the downwards direction away from the rising bubbles (the velocities are referred to an observer at rest with respect to the liquid far from the bubbles). Thus the liquid velocity is the usual wake behind objects moving in viscous Newtonian fluids and the phenomenon is called `negative wake'.
Original languageEnglish
JournalNature
Volume279
Issue number5712
Pages (from-to)402-403
Number of pages2
ISSN0028-0836
DOIs
Publication statusPublished - 1979

Cite this

Hassager, Ole. / Negative wake behind bubbles in non-newtonian liquids. In: Nature. 1979 ; Vol. 279, No. 5712. pp. 402-403.
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title = "Negative wake behind bubbles in non-newtonian liquids",
abstract = "Gas bubbles rising by gravity in non-Newtonian elastic liquids are different to gas bubbles in viscous Newtonian fluids in at least two ways. First, the bubbles in the non-Newtonian liquids often have a peculiar tip at the rear pole, and second, the terminal rise velocity versus volume curve often has a discontinuity at a certain `critical' volume. To investigate this unusual flow situation further laser-Doppler anemometry was used to measure the liquid velocity in the weak behind air bubbles in a non-Newtonian liquid. The measurements reveal the unexpected result that the liquid velocity behind the bubbles is in the downwards direction away from the rising bubbles (the velocities are referred to an observer at rest with respect to the liquid far from the bubbles). Thus the liquid velocity is the usual wake behind objects moving in viscous Newtonian fluids and the phenomenon is called `negative wake'.",
author = "Ole Hassager",
year = "1979",
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language = "English",
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pages = "402--403",
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number = "5712",

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Negative wake behind bubbles in non-newtonian liquids. / Hassager, Ole.

In: Nature, Vol. 279, No. 5712, 1979, p. 402-403.

Research output: Contribution to journalLetterResearch

TY - JOUR

T1 - Negative wake behind bubbles in non-newtonian liquids

AU - Hassager, Ole

PY - 1979

Y1 - 1979

N2 - Gas bubbles rising by gravity in non-Newtonian elastic liquids are different to gas bubbles in viscous Newtonian fluids in at least two ways. First, the bubbles in the non-Newtonian liquids often have a peculiar tip at the rear pole, and second, the terminal rise velocity versus volume curve often has a discontinuity at a certain `critical' volume. To investigate this unusual flow situation further laser-Doppler anemometry was used to measure the liquid velocity in the weak behind air bubbles in a non-Newtonian liquid. The measurements reveal the unexpected result that the liquid velocity behind the bubbles is in the downwards direction away from the rising bubbles (the velocities are referred to an observer at rest with respect to the liquid far from the bubbles). Thus the liquid velocity is the usual wake behind objects moving in viscous Newtonian fluids and the phenomenon is called `negative wake'.

AB - Gas bubbles rising by gravity in non-Newtonian elastic liquids are different to gas bubbles in viscous Newtonian fluids in at least two ways. First, the bubbles in the non-Newtonian liquids often have a peculiar tip at the rear pole, and second, the terminal rise velocity versus volume curve often has a discontinuity at a certain `critical' volume. To investigate this unusual flow situation further laser-Doppler anemometry was used to measure the liquid velocity in the weak behind air bubbles in a non-Newtonian liquid. The measurements reveal the unexpected result that the liquid velocity behind the bubbles is in the downwards direction away from the rising bubbles (the velocities are referred to an observer at rest with respect to the liquid far from the bubbles). Thus the liquid velocity is the usual wake behind objects moving in viscous Newtonian fluids and the phenomenon is called `negative wake'.

U2 - 10.1038/279402a0

DO - 10.1038/279402a0

M3 - Letter

VL - 279

SP - 402

EP - 403

JO - Nature

JF - Nature

SN - 0028-0836

IS - 5712

ER -