## 4.2. Decomposing SPH Calculations

Decomposing SPH parts adopts a similar approach to that applied for grid calculations, though there is no manual option to decompose the problem.

Load in the SPH problem SPHTAY from the samples directory within the Autodyn distribution.

This is an iron Taylor Test problem where the deformation of a cylinder is studied after impacting a wall at 221 ms-1. The model consists of a single SPH object made up of 18540 SPH nodes. Running the model to 0.06 ms will produce the following results:

To decompose the model, click the Parallel button on the Setup toolbar and activate parallel processing by selecting the appropriate check box.

Following the same method as when decomposing the Lagrange calculation; click Add in the Decomposition Sets section of the Parallel Processing panel. Again enter `TWO` as the name of the decomposition and click Sub-domains, which will result in the following window being displayed.

Enter `2` in the Number of Task for SPH text box and click the check button.

Now, click Task Assignments button on the main Parallel Processing panel. The following window will be displayed.

By default, the Automatic option button will be selected. By leaving the default setting, the sub-domains would be assigned to tasks at runtime. As we wish to view the decomposition, select the Manual option button, which will result in further options being displayed.

If we wished to assign the entire SPH object to one task, which may be a viable option if the model contained multiple parts, we would enter the task number in the Assign to task text box and click Assign Now button. As the model consists of a single SPH object we need to decompose the object onto the two available processors in order to efficiently compute the results.

Select the Balance automatically option button and the available options will be modified.

The number of tasks will automatically be placed in the Number of tasks text box and therefore we only have to click Balance Now in order to assign the SPH nodes to the different tasks. Autodyn will attempt to assign the nodes in the most efficient configuration possible for parallel processing. After doing this, click the check button to change the focus back to the main Autodyn window. Select the Plot parallel decomposition check box and the decomposition will be displayed.

The model can be now efficiently run as a parallel computation.

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