Droplet on a fiber: Geometrical shape and contact angle

This paper is concerned with the geometrical shape, wetting length, and contact angle of a microdroplet on a fiber by using the method free energy variation. The governing equation and relevant boundary conditions of the microdroplet were re-derived based on the free energy variation of the droplet/fiber system. The geometrical shape of the droplet was determined as the combination of Legendre’s elliptical functions of the first and second kinds, corresponding to the previous results in literature [6]. For contact angle θ >15°, a novel efficient semi-analytic approach was proposed to extract the contact angle from experimental data. The given approach can be used as theoretical basis of determining surface tension of fluids based on a sessile drop on a fiber.