  The introduction of lubricant between fluid and substrate endows the
Liquid-Infused Slippery Surfaces with excellent wetting properties: low contact
angle, various liquids repellency, ice-phobic and self-healing. Droplets moving
on such surfaces have been widely demonstrated to obey a
Landau-Levich-Derjaguin (LLD) friction. Here, we show that this power law is
surprisingly decreased with the droplet accelerates: in the rapid droplet
regime, the slippery surfaces seem more slippery than LLD friction. Combining
experimental and numerical techniques, we find that the meniscus surrounding
the droplet exhibits an incompletely developed state. The Incompletely
Developed Meniscus possesses shorter shear length and thicker shear thickness
than the prediction of Bretherton model and therefore is responsible for the
more slippery regime. With an extended Bretherton model, we not only provide an
analytical description to the IDM behavior but also the friction when the
Capillary Number of the moving droplet is larger than the Critical Capillary
Number.
