Evaporating sessile drops subject to crosswind.

We conducted an experimental investigation on the evaporation of sessile drops subject to an airflow in crosswind arrangement compared with the naturally developing ascending vapor plume and with air speeds up to almost 2 m/s using ethanol, water and a single malt Scotch Whisky as liquids and Teflon as substrate material. We used Infra-Red to map the temperature evolution of the drying drops curved interface and also measured the drop contact angles. We report a significant decrease in temperature of the drop apex as the air speed is increased. The Infra-Red measurements detect also the location of the contact line which remains mainly pinned for drying water and whisky drops, whereas it is greatly affected in the case of drying ethanol drops. The temperature measurements of ethanol drops clearly demonstrate that during the first stage of drop evaporation with pinned contact line, the drop contact line temperature decreases noticeably. In the subsequent stage of contact line de-pinning and constant contact angle, the contact line temperature remains broadly the same. After drop deposition, experimental values of temperature deviate noticeably from the models of Hu and Larson [31] and Semenov et al. [32] and this might be due to the fact that evaporation is not uniform and constant along the drop. • The Infra-Red measurements detect the location of the contact line around the whole drop perimeter. • Ethanol drops show several de-pinning which are not present for water and Whisky drops at all air speeds investigated. • Ethanol drops show significant decrease of contact line temperature in the first stage of drop evaporation with CCR. • The subsequent stage of ethanol drop evaporation shows contact line temperature broadly the same. [ABSTRACT FROM AUTHOR]