7.7     Simulation Freeze

 

QuickWave enables an advanced feature, which permits to interrupt the simulation and store the current state of QW‑Simulator (with all variables) on disk, in the purpose to restore this state, view results for this state or continue calculations in the future. This feature is called Freeze Simulation. The state of QW-Simulator is saved to *.sfr file. At a convenient time, the simulation can be resumed (defreezed) at the frozen point via File-Open and Run commands. All QW-Simulator functions work in the same normal manner after defreeze operation. Freeze Simulation is very convenient feature in many situations. Below there are typical scenarios:

One example of application can be a display of steady-state moving images in large and possibly high-Q structures. While a long time to reach the steady state may be required, sometimes we need to display the steady-state upon request.

Note that for large projects user has to take into account amount of also large hard disk space used during freeze operation, which is approximately equal of the project RAM memory requirements.

 

The Freeze functionality is not available for:

 

Attention: Note that a *.sfr file contains a complete description of the analysed example, including all the shape and parameter data which would otherwise be read by QW-Simulator from *.sh3 and *.pa3 files. Therefore if the current simulation has been started on a *.pa3 or *.ta3 file, the freeze operation will look for all the relevant *.sh3 and *.pa3 files, and will not be correctly accomplished if some of these files have been deleted from the current directory. Only if the current simulation has been started on a *.sfr file, no *.pa3 or *.sh3 files will be needed by freeze; instead, successive freeze commands will copy relevant shape / parameter contents of the original *.sfr file into new successive *.sfr files. The *.sfr file does not include information from the original *.ta3 file. In other words, if the original *.ta3 file contains a more complicated sequence of tasks than a simple Run, it is the user's responsibility to preserve this file separately. To continue the original sequence of tasks, the original *.ta3 file must be modified by deleting the tasks already completed, and preceding the remaining tasks within RunFreezeIter or RunFreeze on the frozen *.sfr file. There is however one exception from this rule, which involves a certain group of tasks, e.g. Save_Full_Volume_Envelope that accumulate simulation data over user declared number of iterations. If simulation freeze is performed when one of those tasks is in progress, the accumulated data will be saved in *.sfr file and after unfreezing the simulation this task will continue. It is worth noting that different situation has a place for Breakpoints. If the user defines Breakpoints for the project and then performs Freeze operation, all the breakpoints commands that were in progress or were defined to be started after the iteration of freeze, will be continued, or invoked, after unfreezeing the simulation

Note that *.sfr files may require significant disk space - for example, approximately 1.8 MB will be needed for such a small project as the standard/wgtocx1.pro. The freeze files contain information about fields and post-processing (e.g. accumulated Fourier transforms); they do not contain information about windows (display contents and layouts), buffers (e.g. for constructing field envelopes or heating patterns), and breakpoints.