## 4.4. Decomposing Euler-Lagrange Coupled Problems

In the following mine blast example, you will create a domain decomposition set for an analysis where an Euler Ideal Gas parts interacts with a vehicle structure and soil through Euler-Lagrange coupling.

The decomposition of models that include Euler parts interacting with unstructured parts can be applied automatically.

Load in the model MINPAR from the samples directory within the Workbench distribution.

The model consists of an Euler Ideal Gas part (50x20x40) filled with air and two structural parts that model the soil (29.000 Tetra elements) and vehicle (1650 shell elements). The Euler part is filled with high pressurized gas in the region of the soil part where the mine is located and the vehicle will be hit by the blast wave and eroded nodes of the ejected soil. The blast wave interaction is calculated through Euler-Lagrange Interaction and the interaction of the ejected soil and vehicle is modeled through Lagrange-Lagrange interaction and erosion.

If this problem is run for 2 ms and a combined material/velocity vector plot is selected, you will see the following view:

Go to the Parallel Processing panel and select the box to activate parallel processing. Add a decomposition set and call it TWO:

Euler in combination with unstructured parts can automatically be decomposed. Click Set Decomposition. This activates a window in which the information regarding the decomposition can be entered:

The unstructured parts within the model and structured Euler Ideal Gas part will be shown in the Parts to be decomposed window and all are highlighted by default. To decompose the model over two tasks (task 1 and task 2) simply enter `2` into the Number of Tasks box and click Decompose Now:

Click the check button. Select Plot parallel decomposition in the Parallel Processing window to see the following automatic decomposition:

The decomposition algorithm automatically produces a decomposition configuration with good load balancing qualities and minimal inter-processor communication.

To further enhance the efficiency of the coupled calculation the sub-domains of the FE structure are placed on the same processor as the Euler Ideal Gas sub-domains located in the same geometric space. This decreases the necessary inter-processor communication for the coupling calculations, as can be seen below.

In a similar manner the model can be decomposed over 4 slaves:

Again the sub-domains of the FE structure are placed on the same processor as the Euler Ideal Gas sub-domains located in the same geometric space to decrease the necessary inter-processor communication for the coupling calculations, as can be seen above.

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