## Chapter 1: Introduction

Autodyn has been developed specifically for analyzing non-linear, dynamic events such as impacts and blast loading of structures and components. The program offers users a variety of numerical techniques with which to solve their problems. These include Lagrange, Shell, Euler, ALE (Arbitrary Lagrange Euler) and SPH (Smooth Particle Hydrodynamics) solvers. As reliance on computational simulations becomes accepted, the complexity of the problems to be solved increases in size and resolution. However, the practical computation of these very large simulations has been restrained by the lack of performance of available computers. Problems requiring millions of elements and run-times that can run many weeks are not uncommon. Even the fastest single CPUs cannot easily cope with these larger problems.

One approach to overcoming these limitations is to utilize parallel systems. Parallel algorithms are implemented in Autodyn to take advantage of parallel systems that allow simultaneous use of multiple CPUs either on a single multi-processor machine or over a distributed network of computers. This tutorial describes the method used by Autodyn to process problems in parallel and explains how the user sets up and runs a calculation using parallel processing. Autodyn supports the use of a maximum of 127 tasks (slave processes) in a single parallel analysis.

Users set up problems for parallel processing in exactly the same way as they do for serial processing, and the processing of results (for example, plotting, saving) are also performed in the usual way.

The structured as well as unstructured Part calculations of all 3D solvers are parallelized:

- Lagrange (with joins)

- ALE (with joins)

- Shell (with joins)

- SPH (with joins)

- Euler Ideal Gas

- Euler Multi-Material

- Beams (with joins)

Note: Although the joins between unstructured parts are parallelized you are strongly advised to avoid the use of unstructured parts in combination with joins in parallel analyses.

In Autodyn an option is available that will merge joined unstructured nodes that reside at the same physical location in the model into one single unstructured node. The option is available under the Join menu and will increase robustness in many applications involving joins.

Coupled calculations are parallelized between the Euler Ideal Gas and Euler multi-material solver and structured and unstructured Lagrange and Shell solvers.

Interaction calculations are parallelized between Lagrange, ALE, Shell and SPH solvers, using the Gap and Trajectory contact algorithm. Parallel simulations using Trajectory contact are subject to the following restrictions:

- The contact method must be set to penalty; the Decomposition Response method is not available in parallel.

- Trajectory contact cannot be run in parallel when an SPH part is present in the model.

Release 18.2 - © ANSYS, Inc. All rights reserved.