Local vortex formation in bursting air bubble collapsing process
Abstract
The numerical simulation of an air bubble bursting
at a free surface was made in a potential flow of a
viscous fluid assumption, through the Boundary
Element Method (BEM). Such a collapsing process
may involve local vortex formation leading to the
air-liquid interface pinching-off.
Within the BEM formulation, the velocity field and
the potential field can be expressed in terms of either
a distribution of dipoles over the interface, either a
distribution of vortices (a sheet vortex) over the
interface, due to the equivalence between the dipole
and the vortex representation. We highlight that a
potential flow is imposed to the liquid, so that the
vorticity is confined only at the air-liquid interface,
and it cannot diffuse outside the interface. We found
vortex configurations attached to some specific regions
of the interface, where high velocities appear at points
of strong curvature. Those vortex configurations
may produce the interface rupture and air entrainment
during the parent-bubble collapsing process. Once
the velocity field is obtained through BEM over the
whole interface (the velocity potential is explicitly
given under integral form), it can be extended by
subsequent computation to the adjacent liquid, in
order to obtain the velocity field.
Origin : Files produced by the author(s)
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