Coalescence of polymeric sessile drops on a partially wettable substrate

Abstract

Coalescence of sessile polymeric fluid drops on a partially wettable substrate exhibits a transition from inertial to viscoelastic regime at concentration ratio $c/c^{\ast }\sim 1$. Our findings unveil that the temporal evolution of the growing bridge height follows a power-law behaviour $t^b$, such that the coefficient $b$ continuously decreases from 2/3 in the inertial regime ($c/c^{\ast }<1$) to an asymptotic value of 1/2 in the visco-elastic regime ($c/c^{\ast }>1$). To account for fluid elasticity and characteristic time-scale in the viscoelastic regime, a modified thin film equation under lubrication approximation has been proposed using the linear Phan-Thien- Tanner constitutive equation. The temporal evolution of the droplet has been evaluated by solving the modified one-dimensional thin-film equation using a marching explicit scheme. The initial droplet shapes are obtained by re-sorting to energy minimization. A good agreement between numerical and experimental results is obtained.

References in corpus (1)

• Viscous to Inertial Crossover in Liquid Drop Coalescence

Cited by in corpus (2)

• Rheocoalescence: Relaxation time through coalescence of droplets
• Elasticity can affect droplet coalescence