Evaporation control of a drop on fibers

The evaporation dynamics of mist from a fibrous material has important industrial and environmental consequences. In order to understand the drying kinetics of a fiber array, we study a drop sitting on two parallel fibers and, in particular, investigate how the structure and mechanical properties of the material affect the drying dynamics. A drop deposited on two parallel fibers can adopt different shapes, depending on the drop volume, the interfiber distance, the surface tension of the liquid and the fiber radius and elasticity. A given volume of liquid on a given pair of fibers can adopt two distinct morphologies. These two states exhibit different drying kinetics that greatly affects the overall drying time. In addition, flexible fibers undergo deformation that leads to spontaneous spreading, hence to an increased drying rate. The drying kinetics is thus controlled by the fiber elasticity. Furthermore, during evaporation, the drop can change morphology, which counterintuitively results in an increased wetted area during drying.