Development and testing of BlenderFDS, the open, community-based, user interface for NIST FDS

Computational Fluid Dynamics (CFD) tools have increasingly begun to play an important role in risk assessments for fire safety design. NIST Fire dynamics simulator (FDS) seems the CFD modeling tool of first choice for the world-wide community of fire engineers. FDS is being developed as a CFD code only, so no user interface is available to the user, and the input data pre-processing phase is completely left to the user responsibility. In real world cases, especially where complex or curved geometries are to be described, the data input phase represents an important cost for the fire engineer. Back in 2009, in the opinion of the authors, no satisfactory pre-processing tool for this purpose existed. No multi-platform, open source and freely available pre-processing tool existed at all. The lack of an open pre-processor tool motivated the development of BlenderFDS, the open, community-based, user interface for FDS. This paper describes the design process and development choices of this new tool. Then the results of a recent, through evaluation of the tool are presented: BlenderFDS was employed for a fire safety study on Castel Thun, a fascinating medieval castle located at the foot of the Italian Alps. BlenderFDS allowed for a satisfactory control over the input data, and the generated namelists groups. The graphical user interface for 3D solid modeling and intense data sharing between BlenderFDS entities prevented duplication of efforts and lowered the risk of input data errors. This study demonstrates the value of a fully open tool-chain for CFD fire safety analysis. BlenderFDS tool is following the evolution of FDS ecosystem, both in terms of new FDS features and in terms of FDS users' community needs. Its open, bottom-up development model seems to be mostly appropriate to withstand such a challenge.