Fig. 1.

Distinct splashing outcomes for liquid drops impacting on different substrates. (A) Images of the three different substrates: smooth, patterned leaking, and patterned nonleaking substrates. The pore diameter and the spacing between pores are both $75\pm 5\hspace{0.5em}\mathrm{\mu }\mathrm{m}$. The leaking and nonleaking substrates have identical patterns of pores, except that for the former substrate pores are all of the way through whereas for the latter one they are only halfway through. (B) Corresponding splash outcomes for the three types of substrates, for an ethanol drop with diameter $3.5\pm 0.1$ mm and impact velocity $V_0=1.92\pm 0.01$ m/s. Splashing occurs significantly on the smooth substrate, disappears completely on the patterned leaking substrate, and reappears on the patterned nonleaking substrate. It clearly demonstrates that the air entrapment under the drop causes splashing.