Moffatt eddies at an interface

Abstract

It is shown that an infinite set of eddies can develop near the interface–wall intersection in a two-fluid flow. A striking feature is that the eddy occurrence depends on from what side of the interface the flow is driven. In air–water flows where the viscosity ratio is 0.018, the eddies develop if a driving source is located on (i) the air side for \({\alpha < 100.55^{\circ}}\), (ii) any side for \({100.55^{\circ} < \alpha < 146.55^{\circ}}\), and (iii) the water side for \({146.55^{\circ} < \alpha < 159.05^{\circ}}\), where \({\alpha}\) is the upper interface–wall angle.