In case of any evacuation simulation problems, first make sure that all errors that could prevent the simulation are addressed. For more information, see Checking a Project For Errors.
If you ignore the warnings and run the fire dynamics simulation, in this case the simulation may end with the status Error.
Alternatively, the simulation is conducted, but after that you must check that the scene was transferred to FDS correctly.
Contents
- Simulation does not start
- Simulation interrupts unexpectedly
- Simulation ends, but there is no fire
- Simulation takes a very long time
Simulation does not start
First, perform basic script and application settings checks:
- Check that all the necessary elements for the fire dynamics simulation are present in the scenario: fire source, calculation area, registering device in the calculation area.
- Verify that the FDS is installed and configured. For details, see General settings.
- Check that the amount of available RAM is sufficient to run the simulation. For details, see Calculation area.
If after this the simulation still does not start, then pay attention to the following objects: Fire source and Ventilation, as well as Calculation areas in which they are located.
Cause 1
If the cell size of the calculation area is larger than the size of the objects on which the fire and ventilation are located, then in FDS such objects can be transferred as obstacles with zero thickness. FDS does not allow fire sources or ventilation to be located on such obstacles.
Solution
Reduce the cell size of the calculation area so that it is smaller than the size of the objects on which the fire sources and ventilation are located.
Cause 2
For FDS, it is necessary that the fire source and ventilation are completely located on an obstacle. If even a small part of them is located outside the obstacle (hanging in the air), this can lead to an error.
Solution
Make sure that fire sources and ventilation are completely on the surfaces of obstacles.
Cause 3
The fire area is located on an object made of non-combustible material: the properties of the material indicate that it is non-combustible. For more information, see Material Editor.
Solution
Mark the material as flammable and set the required combustion parameters.
Simulation interrupts unexpectedly
Cause
The the fire dynamics simulation results can take up several gigabytes of hard drive space. Before starting the simulation, FDS does not check the available space, but during operation, if the space runs out, the FDS stops working.
Solution
After the simulation is interrupted, check if you have run out of free disk space. If there is no space left, then it is necessary to delete all simulation results and also free up additional space. After this, run the simulation again.
If there is free space on the disk, but the simulation still is interrupted, contact the technical support.
Simulation ends, but there is no fire
Cause
The cell size of the calculation area is larger than the size of the fire source, which leads to the fact that the fire source disappears when the scenario is transferred to the FDS.
Solution
Reduce the cell size of the calculation area so that it does not exceed the size of the fire source.
Sometimes, for large scenarios, it is unacceptable to reduce the cell size of the calculation area, covering the entire building, since this may increase the simulation time and the required RAM. In this case, you can draw an additional calculation area with a smaller cell size around the fire source.
Simulation takes a very long time
One of the main factors that defines fire dynamics simulation time is the size of calculation areas, in which you conduct simulation, and the size of their cells.
Cause 1
The calculation area that you created is too large for the current scenario.
Solution
Reduce the size of the calculation area. Use recommendations for the placement of calculation areas on the scene. For more information, see Recommendations For Reducing Fire Dynamics Simulation Time.
Cause 2
The height of the calculation area is determined by the objects that are located inside its boundaries. The height of the calculation area cannot be less than the height of the floor. Thus, if the height or level of the object that is located within the boundaries of the calculation area is not specified correctly (for example, the height of the wall is set to 3000 meters instead of 3 meters), then the height of the entire calculation area is equal to the height of this object, which will increase the computational load during simulation. Typically (but not always) this error will cause a dialog box to appear indicating that there is not enough RAM.
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Solution
Adjust the height or level of the objects. To quickly find such an object on the scene, it is recommended to view the scene in the rotation mode. For more information, see Additional tools. Make sure that all objects are displayed on the scene.
Cause 3
The cell size of the calculation area is too small.
Solution
Increase the cell size of the calculation area. If you need to conduct the fire dynamics simulatiuon in a specific part of the scene using the calculation area with a small cell size, then place a small additional calculation area with a small cell size above it, and increase the cell size of the other (large) calculation area.
Cause 4
There are too many registering devices in the calculation area.
Solution
The registering device is designed to collect information about how the dangerous fire factors change in the place of its location. If there are many registering devices in the calculation area, this may lead to an increase in the amount of calculations, which can affect the simulation time. We recommend you to place registering devices along the evacuation paths. For more information, see Registering Device. Do not install registering devices where you do not need to collect information about how the DFF change.