On the cusps bordering liquid sheets

Abstract

AbstractThe edge of a stationary radially expanding liquid sheet and the receding rim bordering a plane sheet are naturally indented. It presents a collection of cusps at the extremity of which the liquid concentrates and is expelled. An experimental description of these cusps for a stationary flat inviscid Savart sheet is given. We identify the stable node–jet structure responsible for the deflection of the incoming flow at the rim and demonstrate how these cusps are the structures that accommodate for both mass and momentum conservation at the sheet edge. Their shape, their number around the sheet, and the residual momentum carried by the ejected liquid are computed.