Investigation of Thermocapillary Flows Around Hemispherical Bubbles

Transient thermocapillary induced flows around a hemispherical bubble on a heated wall have been studied using numerical solutions for a wide range of Marangoni numbers (up to 10('6)). Natural convection effects and mass transfer at the bubble interface were included. Two distinct boundary conditions were examined: constant wall heat flux and constant wall temperature. A second order finite difference scheme was adopted for the diffusion terms in the governing equations, while stable upwind schemes were used for the non-linear convective terms. The elliptic stream-function was determined by a relaxation technique. The numerical diffusion effects were also investigated. No significant heat transfer improvement was evident, even for Marangoni number as high as 200,000. The mass transfer process at the bubble interface reduces significantly the thermocapillary activity. High order buoyancy effects tend to cancel thermocapillarity for downward facing bubbles. Natural convection is the dominant mechanism for an upward facing bubble. Thermocapillary flows could be significant in situations where either moderate size stable bubbles at present or high heat fluxes are imposed at the wall.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Jabardo, J.M.S.

• Engineering, Mechanical

Language dc:language

eng

Identifier

(UMI)AAI8127611

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/67034