Why Microgravity:
Gravity driven bubble suspensions are unstable
due to bubble coalescence and significant bubble deformation. Density
matching only works with liquid-liquid or solid-liquid suspensions.
Shear rates produced by bubbles moving at the terminal velocity result
in turbulent flows.
Experiment time scale (suspension preparation, establishment of steady flow and measurement) is significantly larger than aircraft or drop tower microgravity furnished time
How:
Generate a bubble suspension in microgravity.
Shear the suspension in a couette cell. Measure volume fraction distribution
that results from the competition of bubble phase pressure and centrifugal
forces.
Compare results with predictions from suspension
averaged equations and direct numerical simulation.
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Couette Cell
2.5 mm bubbles generated in low gravity
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Bubbles in a Couette cell tend to move toward the inner stationary shell due to centrifugal force. However, dispersed phase pressure resulting from bubble collision will prevent bubble clustering near the inner wall.
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Microgravity Observations of Bubble Interactions (MOBI)
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