Laser-induced convection flow in micro-enclosures

Jupyoung Kim, Purdue University

Abstract

The heat supply through a laser has attracted attentions for last decades. Diverse patterns of temperature gradient due to a laser are related to a variation of material properties. By generating highly non-uniform temperature field in fluid, many phenomena can be generated because of the variation of material properties. This report is composed of four experimental results and discussions regarding laser heating that is supplied by 1064nm continuous wave laser. Velocity is analyzed by 2D &mgr;PIV (Micro Particle Image Velocimetry). First, the Marangoni flow in non-evaporated droplet is studied. Herein, the Marangoni flow is induced from a focused laser. The Marangoni flow is generated due to a gradient of surface tension that is generally inversely proportional to temperature. Consequently, fluid flow in a droplet is generated. To observe a phenomenon only due to laser effect, a droplet is covered with oil layer. By covering a droplet using an oil layer, an evaporation of the droplet is blocked. When a highly focused laser is applied in micro size enclosures, natural and forced convection is generated. Convection study area has been used traditional heating methods such as a heat from a surface or a sphere or a line. Otherwise, laser induce natural and forced convection is novel and can be utilized into many ways by manipulating laser power or shape. Characteristic of convection flow due to a focused laser heating will be investigated. Once AC electric field is applied to a sharp thermal gradient due to a focused laser heating, electrothermal (ET) flow is generated. Physics of the ET flow and relationship between the ET flow and Vpp, frequency, and laser power will be discussed. In addition, material effects on electrothermal flow are performed by changing ITO coated glass to different materials.

Degree

M.S.M.E.

Advisors

Wereley, Purdue University.

Subject Area

Mechanical engineering

COinS