Analysis and experiments on the spreading dynamics of a viscoelastic drop

Abstract

• Spreading dynamics of a sessile viscoelastic drop on a horizontal surface is studied. • Simplified Phan–Thien–Tanner model represents the rheology of the viscoelastic drop. • Theoretical results are validated with our experimental results. • Elastic nature of the viscoelastic fluids reduces the spreading rate of the drop. We study the spreading dynamics of a sessile viscoelastic drop on a horizontal surface, where a simplified Phan–Thien–Tanner (sPTT) model is considered to represent the rheology of viscoelastic drop. We have adopted a macroscopic approach to obtain the temporal evolution of the spreading drop, while to establish the efficacy of the theoretical model, we have validated the results obtained from the mathematical formulation with the experimental results for both the Newtonian (Si-oil) and viscoelastic (PDMS and aqueous solution of CMC and glycerin) drops. Following the framework of Seaver–Berg approximation, the spherical shape of the drop is assumed as a cylindrical disk here. We observe from this study that an increment in the elasticity of the fluid enhances the velocity gradient and increases the viscous dissipation in the drop volume, leading to a reduction in the spreading rate.