Whether you are simulating an explosion or a fire scenario, you need to ignite the flammable mixture to start the combustion phenomenon. The ignition region can be a point (0D), a line (1D), a plane (2D) or a volume (3D).
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 Ignition in CASD.

Add an ignition source in CASD

To define the ignition region, double-click on the parameter Ignition region to expand it.

Edit the Position and Dimension for the ignition region and set the Time of ignition

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

Point ignition region

Surface ignition region

Surface ignition region

Volume 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.