Wind simulation does not result in totally stable results as it is a dynamic process changing over time.
In order to address this problem, the program measures the resulting total forces convergence over a specific time period.
The resultant forces depend on the model size. To properly scale the resultant forces, the program uses the dynamic pressure and the surface values
,
, and
.
The surface values are used to scale the corresponding forces.
This approach allows for the neutralization of disproportions of the model in the wind directions x, y and z.
The scaling forces are calculated as follows:
To measure the total forces convergence over a specific time period, the resultant forces ,
, and
are calculated and stored for a number of steps n, and then the maximum change for a given moment is calculated as follows:
Where ,
, and
represent the stored values of
,
, and
for a given step, and for i=1 to n.
These maximum force changes are then scaled by ,
, and
respectively and displayed as a percentage.
The final metric is the maximum of these three scaled values:
Where = 0,5%, i.e. the default load deviation factor.
n is the number of simulation steps for which ,
, and
are stored for comparison with the current step. The default value for n is 10.