An experimental investigation on EHD effects in the thin-film region of an evaporating meniscus

The laser interferometric method is used to study EHD effects in the thin film region of an evaporating meniscus of DI water, which is formed in the triple-phase contact line region on a vertical heated wall. A columnar electrode, placed horizontally in air (at a relative humidity of 67%) and above the meniscus, is used as the high potential electrode, and the vertical surface coated with an ITO film is used as a heater as well as the low potential electrode. A DC voltage in the range of 0–4500 V is applied to the electrode, and a heat flux of 1.4 W/m2 and 5.6 W/m2 respectively is applied to the ITO film. A high-speed camera is used to record the interference fringes in the thin-film region of the meniscus. It is found that effects of an imposed electric field are the decrease of the contact angle and the meniscus thickness while enhancing its evaporation rate and evaporative instabilities.