How to Model Complex Behavior Using Simple Control Functions

Prior to FDS 5, an FDS user had only a couple of options for controlling the behavior of a simulation An obstruction, a hole, or a vent could be activated or deactivated at a specific time or by a heat detector reaching a specified temperature This was done with keywords for each option on the OBST, HOLE, and VENT inputs As FDS usage increased there were requests for more options – controlling on the basis of flow speed or gas temperature, controlling when a specific number of detectors operated, and other requests It was quickly apparent that adding more and more keywords for each method to all the geometry inputs was going to result in a lot of duplicated code and bloated lists of inputs.

Instead of adding special cases for each method of controlling the simulation, FDS 5 development included a generic approach for doing this.