Marangoni convection: velocity measurements using PTV method around a single vapor bubble

V Carvalho,Y Bailly,M Barthes,V Lepiller

doi:10.1051/meca/2014021

Abstract

An experimental investigation of the Marangoni convection around a single vapor bubble of FC-72 on a downward-facing heated surface was reported. The boiling cell used for this study was equipped with an optical measurement system which was dedicated to the Particle Tracking Velocimetry (PTV) method. This method allowed us to obtain the velocity fields in the liquid around the vapor bubble. From the velocity fields obtained, we verified the presence of Marangoni convection rolls in the vicinity of the liquid-vapor interface. Lastly, the influence of levels of subcooling on the velocity of convective rolls related to the Marangoni effect was investigated.

Highlights

When there is a surface tension gradient along an interface between two immiscible fluids, we may see a fluid movement along this interface called the Marangoni convection
Many studies were carried out on Marangoni convection in the case of an air bubble injected in a liquid layer [2,3,4]
Wozniak et al [7] showed the influence of the liquid’s bulk temperature on the velocity of convective rolls around an air bubble which was injected into a silicone oil layer submitted to a vertical thermal gradient

Summary

Introduction

When there is a surface tension gradient along an interface between two immiscible fluids, we may see a fluid movement along this interface called the Marangoni convection. Many studies were carried out on Marangoni convection in the case of an air bubble injected in a liquid layer (i.e. without phase change) [2,3,4]. Wozniak et al [7] showed the influence of the liquid’s bulk temperature (silicone oil) on the velocity of convective rolls around an air bubble which was injected into a silicone oil layer submitted to a vertical thermal gradient. They deduced from the traking of Liquid Crystal tracer particles the velocity of convective rolls. It had a conical shape with a diameter of 100 μm and an apex angle of 45◦

Boiling cell

PTV system

Results-discussion

Conclusion