## 17.4. Parallel - Automatic Decomposition of Euler parts

The automatic decomposition algorithm also incorporates Euler parts, Ideal Gas as well as Multi-material, in addition to its ability to handle unstructured grids. This facilitates the decomposing of complicated Euler/Lagrange coupled models—you need only stipulate the number of tasks over which the model should be assigned and Autodyn will automatically produce a decomposition configuration with good load balancing qualities and minimal inter-processor communication. Furthermore, to further enhance the efficiency of coupled calculations the subdomains of the Lagrange structure will be placed on the same processor, so decreasing the necessary inter-processor communication.

To automatically decompose an Euler model, go to the Parallel dialog panel as seen below, activate parallel processing and add a new decomposition set which in this instance is called 'two':

Click the Set Decomposition button and all Euler parts will be shown in the Automatic Decomposition dialog window:

Input the number of tasks you want to decompose the part over and click the Decompose Now button. In this case the number of tasks is two and the following decomposition can be viewed:

More complicated decompositions can also be easily achieved. Here the part is decomposed over 16 tasks:

As previously stated, the new algorithm allows easy decomposition of complicated coupled models which include Euler and unstructured Lagrange Parts. The model below contains a brick structure in which an explosion is occurring. The brick structure is modeled using Lagrangian parts, while the explosion in air is modeled using an Euler part. Here, only the lower region of the Euler part is shown for illustration purposes; the Euler part extends above the brick structure.

The Decomposition Set window dialog will contain all of the parts and by default they will all be highlighted:

By choosing decomposing the model over 4 tasks, the various parts can be assigned to the available processors whilst ensuring efficient parallel computations:

If you want to override this decomposition, then the Euler part can still be manually decomposed as before.

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