HEDSA Webpage Contribution
If you would like to visit the WiSTL homepage click
here, or if you would like to learn more about the high energy density science association,
The following image appears on the HEDSA webpage and shows the volume
fraction (top half) and density (bottom half) from a numerical experiment where
an initially spherical helium bubble has been subjected to a planar shock wave
and undergone a significant amount of deformation.
Jeff Greenough (LLNL) has graciously made available the
RAPTOR code for these studies. The planar shock wave
moves in the positive y-direction as shown in the
computational domain on the right. Quarter-symmetry is
assumed in this 3D simulation and O and R represent a outflow
and reflective boundary conditions, respectively. A
Cartesian mesh is employed with 2 levels of adaptive mesh
refinement (each have a refinement of 4 to 1), and at the finest
resolution level, the bubble radius has 100 cells. There
are approximately 107 cells in the domain and the
computation takes 17 hours on a high performance supercomputer
using 512 processors.
A light (helium) spherical bubble is initially at rest in the nitrogen domain
and is impulsively accelerated by a M=2.95 planar shock wave. The
interaction of the shock wave with the bubble results in baroclinic vorticity
deposition on the interface due to misaligned pressure and density gradients.
The shocked bubble image is from a time 700 ms after
the shock wave has first reached the upstream pole of the bubble. A majority
of the He is confined to the primary vortex ring (shown as the light blue region
in the density image) while a much smaller fraction has been spun off downstream
forming secondary and tertiary vortex rings that lag behind the primary by
several initial bubble diameters. These numerical experiments are
complementary to laboratory experiments we are actively engaged in.