A droplet of radius a moves with kinetic energy 2 pi rho U-d(c)'(2)a(3)/3 i
n an incompressible, continuum ambient gas and rebounds from an initially p
lanar, weakly deformable interface bounding a half-space of liquid. We stud
y the rebound process in the limit We(d)equivalent to rho U-d(c)'(2)a/sigma
much less than1, where sigma is the surface tension of the two liquid-gas
interfaces and rho (d) is the density of the fluid comprising the drop and
the planar half-space. When viscous dissipation in both the ambient gas and
in the drop is negligible, the flow inside the drop is inviscid and driven
by the deformation of the near contact dimple region. The dimple region is
approximated as a section of a sphere of radius 2a. Analysis of the motion
induced in the liquid phase, coupled with a physically appropriate descrip
tion of the interfaces, provides a theoretical description of the deformati
on and flow modes that ensue. Analytical predictions based on a singular pe
rturbation analysis valid in the limit ln(We(d)(-1/4))much greater than1 in
dicate that the time taken by the drop to complete a bounce is a We(d)(1/2)
U(c)'(-1)pi (4/3)(1/2) ln(1/2)(We(d)(-1/4)) and the angular extent of the n
ear contact region which undergoes strong deformation is (4We(d)ln(-1)(We(d
)(-1/4))/3)(1/4). The asymptotes are compared to numerical solutions to the
full governing equations. (C) 2001 American Institute of Physics.