Free-surface dynamics of small pores

• We consider the contraction of small pores nucleated in fluid sheets.
• We characterize the pore dynamics solving the full Navier–Stokes system.
• A scaling function without free parameters describes the size of closing pores near collapse.
• Contracting pores may reverse the direction of motion (flicker) and expand.

When the size of a pore nucleated in a fluid sheet is sufficiently small, the pore will contract and close driven by its large radial curvature. The dynamics of small contracting pores are relevant to a number of natural systems and practical applications, from fission pores in cell membranes to the fabrication of nanopores in sensors for DNA sequencing. Here, we report high-fidelity numerical simulations that provide detailed insight into the mechanisms of pore contraction and collapse in fluid sheets of low viscosity. Results uncover a scaling law that predicts the radius of a closing pore as a function of the time to collapse without free parameters. Simulations also show that contracting pores do not always proceed to collapse. Instead, some contracting pores reverse the direction of motion and expand.