[parsec-users] fluidanimate questions

Hampton, Mark mark.hampton at intel.com
Fri Jul 25 11:23:56 EDT 2008


Hi,

 

I had a couple of questions about the fluidanimate benchmark.  First,
the README in the source code directory states that two different
parallelization algorithms are provided-a shared grid algorithm and a
ghost layer algorithm.  However, I only see the shared grid algorithm in
parallel.cpp, which relies on the border[] array to indicate boundary
cells.  Is there still the intention of providing a ghost layer
algorithm?

 

My second question had to do with the method used to advance from one
frame to the next (in both the serial and parallel versions of the
code).  Once the densities, forces, and collisions have been computed,
the AdvanceParticles() function is called so that the particle positions
can be updated.  The updates take place in the cells[] array.  However,
at the beginning of the next frame, when RebuildGrid() is called, the
contents of the cells[] array are overwritten using the contents of the
cells2[] array-and the latter structure is initialized in InitSim() and
never updated again.  So if I'm reading the code correctly, all of the
particle positions will end up being reset to the same values at the
beginning of every frame, rather than actually being updated as the
particles move within/between cells.  Is this a bug, or am I missing
something?  Thanks.

 

Mark

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