Enter the x, y, z dimensions (meters) and your expected HRR
NOTE: The calculator presented below is only indicative mesh size, and a grid sensitivity analysis should be used to verify the mesh size used.
The source of the tool can be found at (https://github.com/koverholt/fire-tools/tree/master/Web_Tools)
For simulations involving buoyant plumes, a measure of how well the ﬂow ﬁeld is resolved is given by
the non-dimensional expression D*/δx, where D* is a characteristic ﬁre diameter:
and δx is the nominal size of a mesh cell. The quantity, Q˙, is the total heat release rate of the ﬁre. If it changes over time, you should consider the corresponding change in resolution. The quantity D*/δx can be thought of as the number of computational cells spanning the characteristic (not necessarily the physical) diameter of the ﬁre. The more cells spanning the ﬁre, the better the resolution of the calculation. It is better to assess the quality of the mesh in terms of this non-dimensional parameter, rather than an absolute mesh cell size. For example, a cell size of 10 cm may be 'adequate,' in some sense, for evaluating the spread of smoke and heat through a building from a sizable ﬁre, but may not be appropriate to study a very small, smouldering source.
There are a number of special output quantities that provide local measures of grid resolution which should be considered in addition to the quantity above. They are listed below.
A Posteriori Mesh Quality Metrics
Measure of Turbulence Resolution
Wavelet Error Measure
Local Cell Reynolds Number
Near-Wall Grid Resolution
This application was developed based on the information provided in the FDS User Guide (NIST Special Publication 1019 Sixth Edition).