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Manycore molecular dynamics

An aim of world's biggest experiments, like LHC at CERN and also FAIR at the GSI at Darmstadt, is to gain information about matter in it's primitive state. Heavy ions are collided under highest energys to recreate a state, which existed within the beginning of the universe.

The UrQMD package of the Frankfurt University simulates this collisions respecting both relativistic and quantum effects. Aim of the "manycore molecular dynamics"-project is to redesign UrQMD's algorithms to fit on modern computer architecture like manycore systems. Thus beeing done, one can compare a large amount of "theoretical experiments" out of computer with the results obtained by LHC or FAIR.

  • A ball of energy 'melting' in the center of the grid

The Hydro Phase

In the newest version of UrQMD it has been enhanced by a hydro phase. Just after the "fireball state" of the collision the behaviour of the collided nuclei is simulated by SHASTA, a CFD algorithm which specially fits to the needs about shock waves and obeyes the constrains of relativity. Using CFD, a more precise simulation of physics is guaranteed.

As the classical FORTRAN implementation of SHASTA was very time and memory consuming, we have redesigned the code in C++. Respecting the paradigm of object oriented programming, the new code is easier to maintain and to enhance than the classical version. Main goal in redesign process, though, was to be able to benefit from modern computer architecture. In a second step we've tested a vectorized version and work on a OpenCL Version for GPGPU use.

So far, just by redesign of the code to make a better cache usage and use less memory access, we have reached a speedup by a factor of two, while our memory consumption has decreased by a factor of five. Thus allowing us to compute more events per hour of cluster usage.

 

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