FDS cell size
This tool allows users to determine the right size for the FDS cells according to McGrattan et al.(2010).
"For simulations involving buoyant plumes, a measure of how well the flow field is resolved is given by the non-dimensional expression D*/x, where D* is a characteristic fire diameter and x is the nominal size of a mesh cell."
In a sensitivity analysis (Hill et al., 2007), sponsored by the U.S. Nuclear Regulatory Commission, the D * / x value ranges between 4 and 16.