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Recently, Fluent worked with Raytheon to complete a benchmark validation
study that demonstrates RAMPANT's accuracy for the solution of a supersonic
missile-related flow problem. RAMPANT was used to solve viscous flow past
a generic missile, at Mach 3.94 and an angle of attack of 20 degrees.
RAMPANT's explicit algorithm is ideally suited to solve this class of
flows.
The grid for the missile geometry was provided by Dr. B. N. Srivastava,
Raytheon Company. To significantly reduce the time to convergence, RAMPANT's
parallel processing capabilities were used. This allowed us to take advantage
of all the available computing resources, running on a cluster of 10 SGI
Indigo2's which were idle at night, and an 8-processor Convex Exemplar
during the day. The ability to run the parallel version of RAMPANT over
a network of workstations, and on dedicated parallel platforms, resulted
in fast turnaround time for the solution.
Wind tunnel test data was available for comparison to the CFD results.
All comparisons were "blind", with the data released only after the completion
of the computation. The key aerodynamic coefficients of interest were
the normal force coefficient and the moment coefficient. A viscous solution,
using the standard k-e turbulence model, yielded excellent agreement with
the wind tunnel data. The predicted normal force was within 2.3 % of the
experimental value and the predicted moment coefficient was within 0.3
% of the experimental results. With this level of accuracy, missile performance,
trajectory, and loading can be predicted, providing valuable insight into
designs.
Pathlines illustrate the flow around the missile at an angle of attack of 20 degrees. In blind comparisons, the RAMPANT results matched the
data extremely well.
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