Calculate Wind Field for 10 Sec

This initial wind field calculation ensures that most of the features of the flow field are well developed before the main calculation routine is started.
The time of 10 sec was set more or less arbitrarily and is a compromise of time spend and maximum obtainable effect.
Normally, after this phase of 10 sec, the change in the wind field should be less than 1% of the geostrophic wind speed at the model top.

Possible Problems & Solution

The wind field change is still above 10% after 10 sec

As ENVI-met remarks, you should increase the border grids, if the problem is at one of the borders.
If the problem is between a high building and the model top, you should increase the total model height.
In case you have very tall buildings in your model and do not want to change the model area you can tell ENVI-met to clip buildings at a certain height. To do so go to the Advanced Settings Panel and change the value for “Maximum allowed Building Height
The problem might also be inside the model are, where those modifications do not help (e.g. due to a jet effect between two buildings or at a corner).
In this case, have a look at the output (if available) and consider to vary the model configuration a little bit at the suspicious corners.
See also Knowledge Base 10: Flow Problems

If a high divergence remains after the 10 sec, the model will start but there is a high possibility that one of the later model operations will end in an numerical error.

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