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By Thomas Gessner, Fluent Inc.; and Daniel L. Cler, Benet Laboratories, US Army, Watervliet, NY
In contrast to the creative but cumbersome approach of using FLUENT’s
“Execute Command” functionality for dynamic solutionbased
adaption, FLUENT 6.1 provides an easy to use dynamic adaption capability
for transient, as well as steady state computations. In addition to the
derivatives FLUENT 6.0 uses to control the adaption, FLUENT 6.1 provides
scaled and normalized derivatives (gradient and curvature) that do not
require the user to readjust the adaption parameter during the computation.
Grid colored by cell refine level (100,000 cells) at an intermediate time
Grid colored by cell refine level (135,000 cells, with a maximum adaption
level of seven) shortly before the shot exit
Recent simulations have made
use of the new dynamic adaption
capability. Benet Laboratories has
kindly provided the geometry and
flow conditions, and this challenging
case will become part of the test
matrix used to validate future versions
of FLUENT 6. Density contours
at 350ms are in very good accordance
with the experimental results
from the previous article. The resolution
of the shocks has improved,
because a higher level of refinement
can now be used. Finally a sobering
statistic on the efficiency of
dynamic adaption: if the entire
domain (a rectangle of 7,000 by
3,500mm) were resolved to the same
level as the resolution of the shock
in the present example, about 133
million cells would be required. Given
the 135,000 cells used for the adapted
case, the cell count is better by
a factor of 1,072!
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