Model Structure and Boundary Conditions

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Particle Simulation of a Micro Bubble Heat Pump
with Parallelized DSMC
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Ping Jiang, Francois Labelle CS267 Final
Project, Spring 2000
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Model Structure and Boundary Conditions
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DSMC Technique and Its Applications

• DSMC Direct Simulation, Monte Carlo
• Representative particles are used
• Particle behavior simulated stochastically based
  on Boltzmann Equation
• Physical quantities of interest are computed as
  averages
• Widely used for studying high Kn (l/l) gas
• Several orders of magnitude faster than Molecular
  Dynamics.

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Steady State Solution
Temperature Profile
Density Profile
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Parallelization Block Decomposition
Processor Assignment (Particles in Proc2 shown)
Next time step Particle transfer needed!
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Parallelization Cyclic Decomposition
Processor Assignment (Particles in Proc2 shown)
Next time step Large particle transfer needed!
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Speedup and Communication Costs
Experimental results for 3 decomposition
strategies on two different architectures
We only do a small number of large memory
transfers, so latency is not an issue, but
transfer rate is.
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Performance Explained Vampir Traces
Cyclic Lots of communication, but naturally load
balanced
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Blocked Low communication, but load seriously
unbalanced
Blocked with Load Balancing Best of all!
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Load Balancing