Variation in Results Due to User Effects in a Simulation with FDS

Abstract

Abstract. The results from a round-robin study in which practicing fire safety engineers simulated the same scenario are presented in this paper. The simulation task included the simulation of an 800 mm heptane pool in a three-room apartment. The participants, representing eight Swedish consultancy firms, simulated the well-specified scenario with FDS 5. The participants received information about the building, the fire mass loss rate and initial conditions. The task was performed a priori, meaning that the participants were not given any experimental or simulation results prior to performing the task. The study shows that there is a variation between the participants in how the input file was specified, the choice of input data and the types of devices used in FDS. The differences in how the fuel and the burner were described were relatively large, which resulted in large differences in mass loss rate and heat release rate. Furthermore, several of the participants made mistakes when the fire was prescribed and this resulted in a variation in the calculated parameters like the temperature increase, which was 300 K in the fire room and 50 K to 150 K in the adjacent rooms. However, the study shows that when the heat release rate and wall boundary conditions were well defined, good temperature predictions could be made.

A Round Robin of fire modelling for performance‐based design

“…The participants had worked with FDS for 3 years on average and a majority of the participants had participated in 15 or fewer projects that included FDS simulations (see Figure 2) this indicates that the participants' experience was slightly lower than the participants in the previous Lund University study 2,9 …”

“…Of these, nine sent in complete results and answered the digital follow‐up questionnaire. The questioner was constructed in a similar way as the questionnaire used in the previous Lund University study 2,9 . The nine participants represented eight different companies.…”

“…This corresponds to the self-assessment made by the participants in the previous study. 2,9 It is hard to draw any conclusions from this, however, since it was voluntary to participate in the study, it can be expected that the participants are more interested in fire modelling than the average fire engineer.…”

“…Typical tasks in Round Robin studies, related to fire science, are exercises to determine the accuracy and precision of fire test methods 4 and tasks related to performance-based design. 2,[6][7][8][9] When it comes to fire modelling, it has been illustrated that a great variation in the results between different users can occur. An example of such a study is the Round Robin study made in connection with the Dalmarnock fire tests in Scotland, 7 where seven participating expert groups were asked to perform separate calculations of the same fire scenario.…”

Existing Improvements in Simulation of Fire–Wind Interaction and Its Effects on Structures

“…The challenge engineers face in simulating the unpredictable nature and behaviour of wind and fire are presented in research done by Johannson and Ekholm [56]. They asserted that there are various assumptions in fire safety engineering.…”