In this article you will learn how to add an ignition region in FLACS.
Add ignition source in CASD
An ignition source is defined in the scenario section called in CASD.
To define the ignition region, double-click on the parameter Ignition region to expand it.
You can define a point, line, surface or volume ignition region. Enter the position coordinates in X, Y and Z directions, respectively. The position you define is the lower left corner of the surface/volume. For a point ignition, leave the Dimension set to zero in all directions. For a surface or volume ignition region, enter the relevant extent(s). Also, you need to specify the Time of ignition. If you do not want any ignition to happen, set the time of ignition to a very high number exceeding the simulation time.
If the ignition point is inside a partially blocked control volume, the ﬂame may quench. It is therefore not recommended to ignite inside a partially blocked control volume. But if you still choose to do so, and if there are any problems to obtain a proper ignition and ﬂame propagation, try to increase the Dimension of ignition region side lengths up to about 0.05-0.10 m.
The ignition region can be directly visualized in CASD during the set-up procedure. Below are some examples of the different types of ignition regions.
Point ignition region
Surface ignition region
Volume ignition region
For explosion simulations it is not recommended to use big 3D ignition regions since this may lead to more violent explosions with overpredicted explosion overpressures.
Other types of ignition regions than point ignition may give inaccuracies and should be investigated carefully.