In highly adaptive irregular problems such as many
Particle-In-Cell (PIC) codes and Direct Simulation Monte Carlo (DSMC) codes, data access
patterns may vary from time step to time step. To efficiently parallelize such adaptive
irregular problems on distributed memory parallel computers, effective methods for domain
partitioning must be addressed. A simple one-dimensional domain partitioning method is
implemented and compared with unstructured mesh partitioners such as recursive coordinate
bisection and recursive inertial bisection.
DSMC Simulations
Sparse Matrix Applications
Computational Combustion
Computational Combustion Publications
Detailed multi-dimensional numerical simulations
provide an ideal vehicle to study fundamental properties of hydrocarbon flames. The
physical processes in hydrocarbon flames are highly complex and interact in a strongly
non-linear fashion. Numerical experimentation is an excellent way to isolate physical
processes, study their interactions, or predict important properties such as flammability
limits. The study of flammability limits is of great practical importance to fire safety.
Near the flammability limit, several physical processes, especially chemistry, become very
important and the interaction among them becomes crucial in determining the flammability
limit. Only highly detailed models which include detailed chemistry and diffusive
processes can obtain the correct flammability limits.
The extinction of hydrocarbon flames is a multidimensional, transient process. To date,
sufficiently detailed calculations for hydrocarbon flames has only been carried out for
steady-state flames. Some preliminary calculations of transient methane flames with
moderately detailed flames have been carried out at the Naval Research Laboratory. These
calculations clearly show the need for including detailed chemistry in hydrocarbon flame
modeling. The reaction scheme used in these calculations used 15 species and 35 reactions.
A complete reaction mechanism for methane would involve 50 species and 200 reactions. For
higher hydrocarbons, which are of more interest to the Navy, the number of species and
reactions is far greater. These calculations are currently beyond the capabilities of
current supercomputers.
Parallel computers are only means currently available to perform these calculations. Thus
it is imperative that the current detailed flame code be ported to a parallel machine. The
existing sequential code has been extensively tested and verified, so to ensure
reliability, the code should be ported with only minimum modification. The PARTI software
will enable us to port the code to a wide variety of parallel computes with limited
disruption to the existing sequential code.
The flame code is not restricted to hydrocarbon fuels and can be generalized to other
energetic fuels. A parallel reactive flow code will provide the Navy with a very powerful
tool to study these fuels.
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