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Restart Types

Flexcom has in fact two restart types. The first involves the application of new loads or boundary conditions in the restart. The case discussed above of a static run followed by a dynamic run falls into this category. When you choose this option, Flexcom takes care to ramp on or gradually build up to their full values only the new loads or boundary conditions, while those loads which were at their full values at the end of the preceding run remain so. This restart type is the one most frequently used.

The second restart type is a simple continuation where the restarted run takes up where the preceding run finished with no new loads or boundary conditions applied. Applications of this option include the staggering of a long simulation over several shorter runs or the continuation of a dynamic regular wave analysis when steady state conditions have not been achieved.

In order to facilitate restart analyses, Flexcom automatically outputs to a binary restart file, at the end of each analysis, sufficient information to enable a subsequent restart to be performed. Earlier versions of Flexcom actually provided an option to request that the restart file also be optionally written periodically while an analysis proceeds, so that in theory if an analysis terminated abruptly before completion (perhaps due to a power failure or a machine crashing), then it would not be necessary to perform the whole analysis again from the very start. In practice however, it was found that the facility was very rarely invoked, and the associated reduction in run-time performance was not justifiable (writing all the restart data to the hard drive at regular intervals can be quite time consuming), so the feature was removed altogether.

Note that the preceding discussion of restart types related specifically to time domain analysis. As already noted, frequency domain dynamic analyses must restart from a converged static solution. So there is essentially only one restart category in this case, corresponding to the first type described above.