Instabilities around a bubble due to combined Marangoni and buoyancy effects

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:484982

Rashidnia, N ^[1]

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1. NYMA Inc., Cleveland, OH (United States). NASA Lewis Research Center

Study of thermocapillary induced motions near bubbles attached to a heated wall in conjunction with the space experiments has received considerable attention in recent years. The author presents results of preliminary 1-G experimental observations which have indicated that when the Marangoni number (which includes the effects of the bubble shape factor) is increased beyond a critical value, a series of oscillatory flows develop in the vicinity of the bubble. This critical Marangoni number can be achieved either by increasing the temperature gradient near the interface in the bulk liquid or enlarging the bubble size. The steady state flow and thermal fields surrounding the bubble are experimentally demonstrated. The transition to oscillatory flow by use of optical techniques is demonstrated. The oscillations have been detected in both sheet for tracing particles, and interferometers for temperature fields were used to visualize these phenomena. Bubble interface oscillations were not detected. The influence of the Marangoni and Prandtl numbers and bubble geometry on the oscillations are indicated.

• Sponsoring Organization: National Aeronautics and Space Administration, Washington, DC (United States)
• OSTI ID: 484982
• Report Number(s): CONF-960815--
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
BUBBLES
CONVECTION
FLUID MECHANICS
GRAVITATION
PHASE TRANSFORMATIONS
STABILITY
TWO-PHASE FLOW
UNSTEADY FLOW