Turbulence in the system of two immiscible liquids

Turbulence in the system of two immiscible liquids

Petr Denissenko, Sergei Lukaschuk, Sergei Poplavski

Laboratory of Fluid Dynamics, The University of Hull

Suspensions of immiscible liquids

We study Energy spectra of two flows:

Flow 1: silicon oil (=3, =0.88)

Flow 2: 80% oil + 20% water-glycerol (60% water, 40% glycerol, =3, =1.1)

Surface tension on the oil-mixture interface = 0.04 N/m. Water-glycerol is coloured by fluorescent dye Rhodamine 6G.

Additional scale: capilary length

Industrial applications: mixing, suspension formation

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0r

0r

l

The study was initiated by the work

Misha Chertkov, Igor Kolokolov,Vladimir Lebedev, U. of Warwick, September 15, 2005

French Washing Machine 9×9×12 cm withCounter-rotating two-blade propellers.

CCD camera 2048x2028 pixeladapted from PIV

Nd YAG pulsed laser, Green, 532 nm

LDA probeBlue, 476 nm

LDA greenBlue, 514 nm

Water-Glycerol mixture visualized by fluorescent dye Rhodamine 6G (yellow)

2-point Velocity measurement by Laser Doppler Anemometer

Water-Glycerol (white) mixing with oil (black)

image27 x 27mm

Pumping scaleL = 60 mm

Capillary scalelc = 10 mm

Viscous scale = 0.3 mm

Same refractive indexSame dynamic viscositySame density (not yet)

Refractive index and viscosity (3 10-3 Pas) are matched between Silicone Oil and Water-Glycerol phases by adjusting Water-to-Glycerol proportion (40% Glycerol) and the Temperature (37°C).

Density may be matched by choosing the composition of Silicone Oil

French Washing Machine 9×9×12 cm withCounter-rotating two-blade propellers.

CCD camera 2048x2028 pixeladapted from PIV

Nd YAG pulsed laser, Green, 532 nm

LDA probeBlue, 476 nm

LDA greenBlue, 514 nm

Water-Glycerol mixture visualized by fluorescent dye Rhodamine 6G (yellow)

2-point Velocity measurement by Laser Doppler Anemometer

Camera image

Droplets chosen for FFT analysis

Measurement of droplet size and shape

Decomposition of the bubble shape by circular harmonics

Mode energyMode am

plitude

Mode number

Note! We analyze a section, not the 3D shape.

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Distribution of droplets by diameter

3 rps4 rps5 rps6 rps8 rps

Distribution of WG volume by droplet diameter

Position of maximum

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harmonicper ndeformatio surface ofEnergy

droplet per Energy Surface

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/2 /

dropleta on wavecapillary a offrequency and Length

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surface

n

anakdE

dE

kf

dnknd

Each harmonic at each droplet is assigned the Wavelength, the Frequency, the Energy.

E= d2

Distribution of surface energy by droplet diameter

E= 4 n2an2

Distribution of oscillations energy by droplet diameter

Position of maximum in energy distribution by droplet size

3 rps4 rps5 rps6 rps8 rps

Energy of oil droplets versus energy of fluid

E3/5

5/35/32

5/3

2

3/2

3322

EVE

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llNlE

ls

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French Washing Machine 9×9×12 cm withCounter-rotating two-blade propellers.

CCD camera 2048x2028 pixeladapted from PIV

Nd YAG pulsed laser, Green, 532 nm

LDA probeBlue, 476 nm

LDA greenBlue, 514 nm

Water-Glycerol mixture visualized by fluorescent dye Rhodamine 6G (yellow)

2-point Velocity measurement by Laser Doppler Anemometer

Laser Doppler AnemometryMoving particle crosses the interference pattern on the intersection of laser beams. Modulation of reflected light gives the particle velocity.

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. . . . . .

. . . . . . ..

Problems: Laser beams are deflectedParticles are leaving the fluid volume to the droplet surface

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..

....

..

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...

.... . .... ...

-4

6 rps5 rps4 rps3 rps

Thick lines: oil onlyThin lines: oil and Water-Glycerol mixture

LDA measurement of energy spectrum in single-phase and two-phase flows

LDA measurements:energy spectrum in pure oil and

in oil + 20% Water-Glycerol mixture

V/lc V/lc

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||

Two-point measurements:velocity correlation in pure oil and

with 20% of Water-Glycerol mixture

Distance between probes, mm

Cor

rela

tion

coe

ffic

ient

rV

SummarySuspension of two immiscible liquids of a similar viscosity is studied.

Droplet shapes are resolved within the suspension.LDA measurements are conducted within the suspension.

Distribution of droplet size and energy spectra of droplet oscillations are measured.Distorsion of energy spectra of fluid motion due to capillary effects is detected.Ratio of surface energy to kinetic energy is measured.

Future plansMatch the fluid densities.

Resolve the spectra below capillary scale.

Perform the two-point LDA measurement of structure functions.