A droplet that impacts onto a solid substrate deforms in a complex dynamics. To extract the principal mechanisms that dominate this dynamics, we deploy numerical simulations based on the phase field method. Direct comparison with experiments suggests that a dissipation local to the contact line limits the droplet spreading dynamics and its scaled maximum spreading radius ${\beta }_{\max }$. By assuming linear response through a drag force at the contact line, our simulations rationalize experimental observations for droplet impact on both smooth and rough substrates, measured through a single contact line friction parameter ${\mu }_f$. Moreover, our analysis shows that dissipation at the contact line can limit the dynamics and we describe ${\beta }_{\max }$ by the scaling law ${\beta }_{\max }\sim {(\text{Re}{\mu }_{\mathrm{l}}/{\mu }_f)}^{1/2}$ that is a function of the droplet viscosity $\left({\mu }_{\mathrm{l}}\right)$ and its Reynolds number $\left(\text{Re}\right)$.

• Received 24 November 2016

DOI:https://doi.org/10.1103/PhysRevFluids.2.033602