FDS Mesh Size Calculator
This tool allows you to easily generate a MESH line for input into Fire Dynamics Simulator (FDS) v5. It automatically finds the optimal (Poisson-friendly) mesh division numbers and returns a complete MESH line to be used in an FDS input file. The cell sizes are determined using a characteristic fire diameter and cell size ratio that should accurately resolve your fire simulation based on the total heat release rate.
The cell size (dx) for a given simulation can be related to the characteristic fire diameter (D*), meaning, the smaller the characteristic fire diamater, the smaller the cell size should be in order to adequately resolve the fluid and fire dynamics.
A reference within the FDS User Guide (Verification and Validation of Selected Fire Models for Nuclear Power Plant Applications. NUREG 1824, United States Nuclear Regulatory Commission, 2007) used a D*/dx ratio between 4 and 16 to accurately resolve fires in various scenarios. From the FDS User Guide: “These values were used to adequately resolve plume dynamics, along with other geometrical characteristics of the models as well. This range does not indicate what values to use for all models, only what values worked well for that particular set of models.”
The characteristic fire diameter (D*) is given by the following relationship:
For more information, see the FDS 5 User Guide Section 6.3 or visit the official NIST FDS Website
Please send any bug reports or comments to me at koverholt@gmail.com